GUARD &7C00 \ Guard against assembling over screen memoryREVS BRANDS HATCH TRACK SOURCE Revs was written by Geoffrey J Crammond and is copyright Acornsoft 1985 The code on this site has been reconstructed from a disassembly of the original game binaries The commentary is copyright Mark Moxon, and any misunderstandings or mistakes in the documentation are entirely my fault The terminology and notations used in this commentary are explained at https://revs.bbcelite.com/terminology The deep dive articles referred to in this commentary can be found at https://revs.bbcelite.com/deep_dives
This source file produces the following binary file: * BrandsHatch.binLOAD% = &70DB \ The load address of the track binary CODE% = &5300 \ The assembly address of the track data trackWidth = 136 \ Track width \ \ [Show more]Configuration variables\ \ This variable is used by the following: \ \ * CalcSegmentVector \ \ This list only includes code that refers to the \ variable by name; there may be other references to \ this memory location that don't use this label, and \ these will not be mentioned abovethisSectionFlags = &0001 thisVectorNumber = &0002 yStore = &001B horizonLine = &001F frontSegmentIndex = &0024 directionFacing = &0025 segmentCounter = &0042 playerPastSegment = &0043 xStore = &0045 vergeBufferEnd = &004B horizonListIndex = &0051 playerSpeedHi = &0063 currentPlayer = &006F T = &0074 U = &0075 V = &0076 W = &0077 topTrackLine = &007F blockOffset = &0082 objTrackSection = &06E8 Multiply8x8 = &0C00 Absolute16Bit = &0E40 UpdateVectorNumber = &13E0 MovePlayerBack = &140B CheckVergeOnScreen = &1933 gseg13 = &2490 gtrm2 = &2535 Absolute8Bit = &3450 MultiplyHeight = &4610 xTrackSegmentI = &5400 yTrackSegmentI = &5500 zTrackSegmentI = &5600 xTrackSegmentO = &5700 zTrackSegmentO = &5800 trackSectionFrom = &5905 xVergeRightLo = &5E40 xVergeLeftLo = &5E68 xVergeRightHi = &5E90 xVergeLeftHi = &5EB8 yVergeRight = &5F20 yVergeLeft = &5F48Addresses in the main game code\ \ [Show more]REVS BRANDS HATCH TRACK Produces the binary file BrandsHatch.bin that contains the Brands Hatch track.\ \ This variable is used by the following: \ \ * HookFixHorizon \ \ This list only includes code that refers to the \ variable by name; there may be other references to \ this memory location that don't use this label, and \ these will not be mentioned aboveORG CODE% .trackData\ Track section 0 EQUB &01 \ trackSectionData sign = 0, sectionListSize = 1 EQUB &D1 \ xTrackSectionIHi xTrackSectionI = &D120 = -12000 EQUB &14 \ yTrackSectionIHi yTrackSectionI = &1400 = 5120 EQUB &0F \ zTrackSectionIHi zTrackSectionI = &0FA0 = 4000 EQUB &D0 \ xTrackSectionOHi xTrackSectionO = &D021 = -12255 EQUB 52 \ trackSectionTurn EQUB &0F \ zTrackSectionOHi zTrackSectionO = &0FA0 = 4000 EQUB 127 \ trackDriverSpeed \ Track section 1 EQUB &13 \ trackSectionData sign = 1, sectionListSize = 3 EQUB &D4 \ xTrackSectionIHi xTrackSectionI = &D4DC = -11044 EQUB &14 \ yTrackSectionIHi yTrackSectionI = &1487 = 5255 EQUB &2A \ zTrackSectionIHi zTrackSectionI = &2A5C = 10844 EQUB &D3 \ xTrackSectionOHi xTrackSectionO = &D3F6 = -11274 EQUB 41 \ trackSectionTurn EQUB &2A \ zTrackSectionOHi zTrackSectionO = &2AC8 = 10952 EQUB 28 \ trackDriverSpeed \ Track section 2 EQUB &22 \ trackSectionData sign = 2, sectionListSize = 2 EQUB &E0 \ xTrackSectionIHi xTrackSectionI = &E052 = -8110 EQUB &0F \ yTrackSectionIHi yTrackSectionI = &0F2B = 3883 EQUB &2D \ zTrackSectionIHi zTrackSectionI = &2DE3 = 11747 EQUB &E0 \ xTrackSectionOHi xTrackSectionO = &E0B5 = -8011 EQUB 255 \ trackSectionTurn EQUB &2E \ zTrackSectionOHi zTrackSectionO = &2ECC = 11980 EQUB 255 \ trackDriverSpeed \ Track section 3 EQUB &31 \ trackSectionData sign = 3, sectionListSize = 1 EQUB &EA \ xTrackSectionIHi xTrackSectionI = &EA2B = -5589 EQUB &0E \ yTrackSectionIHi yTrackSectionI = &0EDE = 3806 EQUB &29 \ zTrackSectionIHi zTrackSectionI = &2996 = 10646 EQUB &EA \ xTrackSectionOHi xTrackSectionO = &EAAA = -5462 EQUB 22 \ trackSectionTurn EQUB &2A \ zTrackSectionOHi zTrackSectionO = &2A73 = 10867 EQUB 73 \ trackDriverSpeed \ Track section 4 EQUB &31 \ trackSectionData sign = 3, sectionListSize = 1 EQUB &F3 \ xTrackSectionIHi xTrackSectionI = &F3EB = -3093 EQUB &11 \ yTrackSectionIHi yTrackSectionI = &116C = 4460 EQUB &23 \ zTrackSectionIHi zTrackSectionI = &23F6 = 9206 EQUB &F4 \ xTrackSectionOHi xTrackSectionO = &F46A = -2966 EQUB 24 \ trackSectionTurn EQUB &24 \ zTrackSectionOHi zTrackSectionO = &24D3 = 9427 EQUB 6 \ trackDriverSpeed \ Track section 5 EQUB &43 \ trackSectionData sign = 4, sectionListSize = 3 EQUB &F1 \ xTrackSectionIHi xTrackSectionI = &F171 = -3727 EQUB &0D \ yTrackSectionIHi yTrackSectionI = &0D53 = 3411 EQUB &1E \ zTrackSectionIHi zTrackSectionI = &1E53 = 7763 EQUB &F1 \ xTrackSectionOHi xTrackSectionO = &F100 = -3840 EQUB 21 \ trackSectionTurn EQUB &1D \ zTrackSectionOHi zTrackSectionO = &1D6D = 7533 EQUB 255 \ trackDriverSpeed \ Track section 6 EQUB &44 \ trackSectionData sign = 4, sectionListSize = 4 EQUB &E6 \ xTrackSectionIHi xTrackSectionI = &E60D = -6643 EQUB &08 \ yTrackSectionIHi yTrackSectionI = &0843 = 2115 EQUB &23 \ zTrackSectionIHi zTrackSectionI = &23EA = 9194 EQUB &E5 \ xTrackSectionOHi xTrackSectionO = &E59C = -6756 EQUB 31 \ trackSectionTurn EQUB &23 \ zTrackSectionOHi zTrackSectionO = &2304 = 8964 EQUB 18 \ trackDriverSpeed \ Track section 7 EQUB &53 \ trackSectionData sign = 5, sectionListSize = 3 EQUB &DE \ xTrackSectionIHi xTrackSectionI = &DE2F = -8657 EQUB &05 \ yTrackSectionIHi yTrackSectionI = &05EB = 1515 EQUB &21 \ zTrackSectionIHi zTrackSectionI = &2120 = 8480 EQUB &DE \ xTrackSectionOHi xTrackSectionO = &DEF0 = -8464 EQUB 1 \ trackSectionTurn EQUB &20 \ zTrackSectionOHi zTrackSectionO = &207A = 8314 EQUB 255 \ trackDriverSpeed \ Track section 8 EQUB &54 \ trackSectionData sign = 5, sectionListSize = 4 EQUB &DA \ xTrackSectionIHi xTrackSectionI = &DA39 = -9671 EQUB &05 \ yTrackSectionIHi yTrackSectionI = &05EB = 1515 EQUB &1C \ zTrackSectionIHi zTrackSectionI = &1C81 = 7297 EQUB &DA \ xTrackSectionOHi xTrackSectionO = &DAFA = -9478 EQUB 39 \ trackSectionTurn EQUB &1B \ zTrackSectionOHi zTrackSectionO = &1BDB = 7131 EQUB 19 \ trackDriverSpeed \ Track section 9 EQUB &53 \ trackSectionData sign = 5, sectionListSize = 3 EQUB &D8 \ xTrackSectionIHi xTrackSectionI = &D836 = -10186 EQUB &05 \ yTrackSectionIHi yTrackSectionI = &05EB = 1515 EQUB &16 \ zTrackSectionIHi zTrackSectionI = &16CE = 5838 EQUB &D9 \ xTrackSectionOHi xTrackSectionO = &D930 = -9936 EQUB 43 \ trackSectionTurn EQUB &16 \ zTrackSectionOHi zTrackSectionO = &16A1 = 5793 EQUB 117 \ trackDriverSpeed \ Track section 10 EQUB &62 \ trackSectionData sign = 6, sectionListSize = 2 EQUB &D9 \ xTrackSectionIHi xTrackSectionI = &D90A = -9974 EQUB &05 \ yTrackSectionIHi yTrackSectionI = &05EB = 1515 EQUB &01 \ zTrackSectionIHi zTrackSectionI = &0152 = 338 EQUB &DA \ xTrackSectionOHi xTrackSectionO = &DA00 = -9728 EQUB 40 \ trackSectionTurn EQUB &01 \ zTrackSectionOHi zTrackSectionO = &018F = 399 EQUB 20 \ trackDriverSpeed \ Track section 11 EQUB &61 \ trackSectionData sign = 6, sectionListSize = 1 EQUB &E5 \ xTrackSectionIHi xTrackSectionI = &E558 = -6824 EQUB &0A \ yTrackSectionIHi yTrackSectionI = &0ADF = 2783 EQUB &FC \ zTrackSectionIHi zTrackSectionI = &FC7C = -900 EQUB &E4 \ xTrackSectionOHi xTrackSectionO = &E496 = -7018 EQUB 1 \ trackSectionTurn EQUB &FD \ zTrackSectionOHi zTrackSectionO = &FD21 = -735 EQUB 123 \ trackDriverSpeed \ Track section 12 EQUB &73 \ trackSectionData sign = 7, sectionListSize = 3 EQUB &EF \ xTrackSectionIHi xTrackSectionI = &EF18 = -4328 EQUB &11 \ yTrackSectionIHi yTrackSectionI = &1173 = 4467 EQUB &07 \ zTrackSectionIHi zTrackSectionI = &07DC = 2012 EQUB &EE \ xTrackSectionOHi xTrackSectionO = &EE56 = -4522 EQUB 255 \ trackSectionTurn EQUB &08 \ zTrackSectionOHi zTrackSectionO = &0881 = 2177 EQUB 255 \ trackDriverSpeed \ Track section 13 EQUB &82 \ trackSectionData sign = 8, sectionListSize = 2 EQUB &06 \ xTrackSectionIHi xTrackSectionI = &0661 = 1633 EQUB &11 \ yTrackSectionIHi yTrackSectionI = &1132 = 4402 EQUB &1B \ zTrackSectionIHi zTrackSectionI = &1B7F = 7039 EQUB &05 \ xTrackSectionOHi xTrackSectionO = &05C5 = 1477 EQUB 255 \ trackSectionTurn EQUB &1C \ zTrackSectionOHi zTrackSectionO = &1C4B = 7243 EQUB 255 \ trackDriverSpeed \ Track section 14 EQUB &81 \ trackSectionData sign = 8, sectionListSize = 1 EQUB &12 \ xTrackSectionIHi xTrackSectionI = &1261 = 4705 EQUB &0E \ yTrackSectionIHi yTrackSectionI = &0E12 = 3602 EQUB &24 \ zTrackSectionIHi zTrackSectionI = &249F = 9375 EQUB &11 \ xTrackSectionOHi xTrackSectionO = &11C5 = 4549 EQUB 19 \ trackSectionTurn EQUB &25 \ zTrackSectionOHi zTrackSectionO = &256B = 9579 EQUB 142 \ trackDriverSpeed \ Track section 15 EQUB &90 \ trackSectionData sign = 9, sectionListSize = 0 EQUB &1B \ xTrackSectionIHi xTrackSectionI = &1B61 = 7009 EQUB &11 \ yTrackSectionIHi yTrackSectionI = &11C0 = 4544 EQUB &2B \ zTrackSectionIHi zTrackSectionI = &2B77 = 11127 EQUB &1A \ xTrackSectionOHi xTrackSectionO = &1AC5 = 6853 EQUB 46 \ trackSectionTurn EQUB &2C \ zTrackSectionOHi zTrackSectionO = &2C43 = 11331 EQUB 23 \ trackDriverSpeed \ Track section 16 EQUB &92 \ trackSectionData sign = 9, sectionListSize = 2 EQUB &2A \ xTrackSectionIHi xTrackSectionI = &2AA6 = 10918 EQUB &15 \ yTrackSectionIHi yTrackSectionI = &15DC = 5596 EQUB &2A \ zTrackSectionIHi zTrackSectionI = &2AF6 = 10998 EQUB &2B \ xTrackSectionOHi xTrackSectionO = &2B63 = 11107 EQUB 50 \ trackSectionTurn EQUB &2B \ zTrackSectionOHi zTrackSectionO = &2BA2 = 11170 EQUB 127 \ trackDriverSpeed \ Track section 17 EQUB &A1 \ trackSectionData sign = 10, sectionListSize = 1 EQUB &3C \ xTrackSectionIHi xTrackSectionI = &3C0D = 15373 EQUB &14 \ yTrackSectionIHi yTrackSectionI = &14C9 = 5321 EQUB &17 \ zTrackSectionIHi zTrackSectionI = &17D7 = 6103 EQUB &3C \ xTrackSectionOHi xTrackSectionO = &3CCA = 15562 EQUB 37 \ trackSectionTurn EQUB &18 \ zTrackSectionOHi zTrackSectionO = &1883 = 6275 EQUB 18 \ trackDriverSpeed \ Track section 18 EQUB &A3 \ trackSectionData sign = 10, sectionListSize = 3 EQUB &3A \ xTrackSectionIHi xTrackSectionI = &3A6B = 14955 EQUB &14 \ yTrackSectionIHi yTrackSectionI = &14A8 = 5288 EQUB &0C \ zTrackSectionIHi zTrackSectionI = &0C7C = 3196 EQUB &3B \ xTrackSectionOHi xTrackSectionO = &3B17 = 15127 EQUB 21 \ trackSectionTurn EQUB &0B \ zTrackSectionOHi zTrackSectionO = &0BBE = 3006 EQUB 255 \ trackDriverSpeed \ Track section 19 EQUB &A2 \ trackSectionData sign = 10, sectionListSize = 2 EQUB &2D \ xTrackSectionIHi xTrackSectionI = &2D35 = 11573 EQUB &11 \ yTrackSectionIHi yTrackSectionI = &1128 = 4392 EQUB &00 \ zTrackSectionIHi zTrackSectionI = &0076 = 118 EQUB &2D \ xTrackSectionOHi xTrackSectionO = &2DE1 = 11745 EQUB 40 \ trackSectionTurn EQUB &FF \ zTrackSectionOHi zTrackSectionO = &FFB8 = -72 EQUB 20 \ trackDriverSpeed \ Track section 20 EQUB &A1 \ trackSectionData sign = 10, sectionListSize = 1 EQUB &29 \ xTrackSectionIHi xTrackSectionI = &29E7 = 10727 EQUB &11 \ yTrackSectionIHi yTrackSectionI = &11AC = 4524 EQUB &FE \ zTrackSectionIHi zTrackSectionI = &FEC6 = -314 EQUB &2A \ xTrackSectionOHi xTrackSectionO = &2A28 = 10792 EQUB 21 \ trackSectionTurn EQUB &FD \ zTrackSectionOHi zTrackSectionO = &FDCF = -561 EQUB 123 \ trackDriverSpeed \ Track section 21 EQUB &B1 \ trackSectionData sign = 11, sectionListSize = 1 EQUB &1D \ xTrackSectionIHi xTrackSectionI = &1D37 = 7479 EQUB &14 \ yTrackSectionIHi yTrackSectionI = &14A0 = 5280 EQUB &FB \ zTrackSectionIHi zTrackSectionI = &FB62 = -1182 EQUB &1D \ xTrackSectionOHi xTrackSectionO = &1D78 = 7544 EQUB 24 \ trackSectionTurn EQUB &FA \ zTrackSectionOHi zTrackSectionO = &FA6B = -1429 EQUB 12 \ trackDriverSpeed \ Track section 22 EQUB &B3 \ trackSectionData sign = 11, sectionListSize = 3 EQUB &18 \ xTrackSectionIHi xTrackSectionI = &18F2 = 6386 EQUB &15 \ yTrackSectionIHi yTrackSectionI = &1509 = 5385 EQUB &FC \ zTrackSectionIHi zTrackSectionI = &FC9E = -866 EQUB &18 \ xTrackSectionOHi xTrackSectionO = &1834 = 6196 EQUB 33 \ trackSectionTurn EQUB &FB \ zTrackSectionOHi zTrackSectionO = &FBF1 = -1039 EQUB 108 \ trackDriverSpeed \ Track section 23 EQUB &C2 \ trackSectionData sign = 12, sectionListSize = 2 EQUB &0C \ xTrackSectionIHi xTrackSectionI = &0CEC = 3308 EQUB &14 \ yTrackSectionIHi yTrackSectionI = &1497 = 5271 EQUB &09 \ zTrackSectionIHi zTrackSectionI = &09D4 = 2516 EQUB &0C \ xTrackSectionOHi xTrackSectionO = &0C2E = 3118 EQUB 27 \ trackSectionTurn EQUB &09 \ zTrackSectionOHi zTrackSectionO = &0927 = 2343 EQUB 13 \ trackDriverSpeed \ Track section 24 EQUB &C1 \ trackSectionData sign = 12, sectionListSize = 1 EQUB &05 \ xTrackSectionIHi xTrackSectionI = &05D0 = 1488 EQUB &15 \ yTrackSectionIHi yTrackSectionI = &1599 = 5529 EQUB &0A \ zTrackSectionIHi zTrackSectionI = &0A0B = 2571 EQUB &06 \ xTrackSectionOHi xTrackSectionO = &067E = 1662 EQUB 255 \ trackSectionTurn EQUB &09 \ zTrackSectionOHi zTrackSectionO = &0950 = 2384 EQUB 255 \ trackDriverSpeed \ Track section 25 EQUB &D3 \ trackSectionData sign = 13, sectionListSize = 3 EQUB &F9 \ xTrackSectionIHi xTrackSectionI = &F970 = -1680 EQUB &19 \ yTrackSectionIHi yTrackSectionI = &1923 = 6435 EQUB &FE \ zTrackSectionIHi zTrackSectionI = &FE83 = -381 EQUB &FA \ xTrackSectionOHi xTrackSectionO = &FA1E = -1506 EQUB 47 \ trackSectionTurn EQUB &FD \ zTrackSectionOHi zTrackSectionO = &FDC8 = -568 EQUB 125 \ trackDriverSpeed \ Track section 26 EQUB &E2 \ trackSectionData sign = 14, sectionListSize = 2 EQUB &E5 \ xTrackSectionIHi xTrackSectionI = &E5D8 = -6696 EQUB &19 \ yTrackSectionIHi yTrackSectionI = &193C = 6460 EQUB &EC \ zTrackSectionIHi zTrackSectionI = &EC41 = -5055 EQUB &E6 \ xTrackSectionOHi xTrackSectionO = &E686 = -6522 EQUB 42 \ trackSectionTurn EQUB &EB \ zTrackSectionOHi zTrackSectionO = &EB86 = -5242 EQUB 24 \ trackDriverSpeed \ Track section 27 EQUB &E1 \ trackSectionData sign = 14, sectionListSize = 1 EQUB &DB \ xTrackSectionIHi xTrackSectionI = &DB15 = -9451 EQUB &16 \ yTrackSectionIHi yTrackSectionI = &16E6 = 5862 EQUB &ED \ zTrackSectionIHi zTrackSectionI = &EDCA = -4662 EQUB &DA \ xTrackSectionOHi xTrackSectionO = &DA64 = -9628 EQUB 255 \ trackSectionTurn EQUB &ED \ zTrackSectionOHi zTrackSectionO = &ED11 = -4847 EQUB 125 \ trackDriverSpeed \ Track section 28 EQUB &F2 \ trackSectionData sign = 15, sectionListSize = 2 EQUB &D3 \ xTrackSectionIHi xTrackSectionI = &D398 = -11368 EQUB &17 \ yTrackSectionIHi yTrackSectionI = &179A = 6042 EQUB &F7 \ zTrackSectionIHi zTrackSectionI = &F7D9 = -2087 EQUB &D2 \ xTrackSectionOHi xTrackSectionO = &D2A5 = -11611 EQUB 255 \ trackSectionTurn EQUB &F7 \ zTrackSectionOHi zTrackSectionO = &F78C = -2164 EQUB 255 \ trackDriverSpeed EQUB &00, &00 \ These bytes appear to be unused EQUB &00, &00 EQUB &00, &34 EQUB &00, &7FName: Track section data (Part 1 of 2) [Show more] Type: Variable Category: Extra tracks Summary: Data for the track sections Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
Brands Hatch consists of the following track sections: 0 -> Clearways to Paddock Bend (3/3) 1 -> Paddock Bend 2 |->| Paddock Bend to Druids (1/2) 3 {} Paddock Bend to Druids (2/2) 4 |->| Druids 5 || Druids to Graham Hill Bend 6 <- Graham Hill Bend 7 || Graham Hill Bend to Surtees (1/3) 8 <- Graham Hill Bend to Surtees (2/3) 9 <- Graham Hill Bend to Surtees (3/3) 10 <- Surtees 11 {} Surtees to Hawthorns Bend (1/4) 12 |->| Surtees to Hawthorns Bend (2/4) 13 {} Surtees to Hawthorns Bend (3/4) 14 {} Surtees to Hawthorns Bend (4/4) 15 -> Hawthorns Bend 16 || Hawthorns Bend to Westfield 17 -> Westfield 18 {} Westfield to Dingle Dell Corner (1/3) 19 -> Westfield to Dingle Dell Corner (2/3) 20 || Westfield to Dingle Dell Corner (3/3) 21 -> Dingle Dell Corner 22 || Dingle Dell Corner to Stirlings 23 <- Stirlings 24 {} Stirlings to Clearways (1/2) 25 {} Stirlings to Clearways (2/2) 26 -> Clearways 27 -> Clearways to Paddock Bend (1/3) 28 -> Clearways to Paddock Bend (2/3) where each section is one of the following shapes: || is a straight section that doesn't curve to the left or right, and has the same gradient throughout the whole section {} is a straight section in the sense that it doesn't curve to the left or right, but the gradient can differ between sub-sections -> consists of sub-sections that all curve to the right <- consists of sub-sections that all curve to the left |->| consists of sub-sections that are either straight or curve to the right |<-| consists of sub-sections that are either straight or curve to the left |<->| consists of sub-sections that are either straight or curve to the left or right This part defines the following aspects of these track sections: trackSectionData Various data for the track section: * Bits 0-2: Size of the track section list Defines the number of entries that we store in the track section list for this section, which is used to calculate the coordinates of the track verges (higher numbers mean more sections are calculated, so higher numbers are used for more complex parts of the track) This value is given in the bottom nibble of the track section data byte (bit 3 is ignored), i.e. the second digit in the hexadecimal value * Bits 4-7: Sign number The number of the road sign (0 to 15) to show when we enter this section, but only if the sign number is different to the number in the previous section This value is given in the top nibble of the track section data byte, i.e. the first digit in the hexadecimal value xTrackSectionIHi High byte of the x-coordinate of the starting point of the inner verge of each track section yTrackSectionIHi High byte of the y-coordinate of the starting point of the inner verge of each track section zTrackSectionIHi High byte of the z-coordinate of the starting point of the inner verge of each track section xTrackSectionOHi High byte of the x-coordinate of the starting point of the outside verge of each track section trackSectionTurn The number of the segment towards the end of the section where non-player cars should start turning in preparation for the next section zTrackSectionOHi High byte of the z-coordinate of the starting point of the outside verge of each track section trackDriverSpeed The maximum speed for non-player drivers on the next section of the track.Hook80Percent STA U \ Set U = A LDA #205 \ Set A = 205 JMP Multiply8x8 \ Set (A T) = A * U \ = 205 * A \ \ returning from the subroutine using a tail call \ \ This calculates the following in A: \ \ A = (A T) / 256 \ = 205 * A / 256 \ = 0.80 * A EQUB &00 \ This byte appears to be unusedName: Hook80Percent [Show more] Type: Subroutine Category: Extra tracks Summary: Set the horizonTrackWidth to 80% of the width of the track on the horizon Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls Hook80Percent * newContentLo calls Hook80Percent
This routine is called from GetTrackAndMarkers to set the horizonTrackWidth to 80% of the width of the track on the horizon..subSection EQUB 0Name: subSection [Show more] Type: Variable Category: Extra tracks Summary: The number of the current sub-sectionContext: See this variable on its own page References: This variable is used as follows: * HookSectionFrom uses subSection * SetSegmentVector uses subSection * UpdateDataPointers uses subSection.trackSubCount EQUB 58Name: trackSubCount [Show more] Type: Variable Category: Extra tracks Summary: The total number of sub-sections in the trackContext: See this variable on its own page References: This variable is used as follows: * UpdateDataPointers uses trackSubCount.yawAngleLo EQUB 0Name: yawAngleLo [Show more] Type: Variable Category: Extra tracks Summary: Low byte of the current yaw angle of the track, i.e. the angle at which the track is pointing along the groundContext: See this variable on its own page References: This variable is used as follows: * CalcSegmentVector uses yawAngleLo * HookSectionFrom uses yawAngleLo * SetSegmentVector uses yawAngleLo.yawAngleHi EQUB 0Name: yawAngleHi [Show more] Type: Variable Category: Extra tracks Summary: High byte of the current yaw angle of the track, i.e. the angle at which the track is pointing along the groundContext: See this variable on its own page References: This variable is used as follows: * CalcSegmentVector uses yawAngleHi * HookSectionFrom uses yawAngleHi * SetSegmentVector uses yawAngleHi.segmentSlope EQUB 0Name: segmentSlope [Show more] Type: Variable Category: Extra tracks Summary: The height above ground of the current track sub-sectionContext: See this variable on its own page References: This variable is used as follows: * CalcSegmentVector uses segmentSlope * HookSectionFrom uses segmentSlope * SetSegmentVector uses segmentSlope.subSectionSegment EQUB 0 EQUB &00, &00 \ These bytes appear to be unusedName: subSectionSegment [Show more] Type: Variable Category: Extra tracks Summary: The number of the segment within the current sub-section, counting from the start of the sub-sectionContext: See this variable on its own page References: This variable is used as follows: * HookSectionFrom uses subSectionSegment * UpdateDataPointers uses subSectionSegment.modifyAddressLo EQUB &49 \ !&1249 = HookSectionFrom EQUB &8A \ !&128A = HookFirstSegment EQUB &CA \ !&13CA = HookSegmentVector EQUB &27 \ !&1427 = HookSegmentVector EQUB &FC \ !&12FC = HookDataPointers EQUB &1B \ !&261B = HookUpdateHorizon EQUB &8C \ !&248C = HookFieldOfView EQUB &39 \ !&2539 = HookFixHorizon EQUB &94 \ !&1594 = HookJoystick EQUB &D1 \ !&4CD1 = xTrackSignVector EQUB &C9 \ !&4CC9 = yTrackSignVector EQUB &C1 \ !&4CC1 = zTrackSignVector EQUB &D6 \ !&44D6 = trackSteering EQUB &D7 \ !&4CD7 = trackSignData EQUB &E1 \ !&4CE1 = trackSignData EQUB &47 \ !&1947 = HookFlattenHills EQUB &F3 \ !&24F3 = HookMoveBack EQUB &2C \ !&462C = HookFlipAbsolute EQUB &43 \ !&2543 = Hook80Percent EQUB &00 \ This byte pads the block out to exactly 20 bytesName: modifyAddressLo [Show more] Type: Variable Category: Extra tracks Summary: Low byte of the location in the main game code where we modify a two-byte addressContext: See this variable on its own page References: This variable is used as follows: * ModifyGameCode (Part 1 of 3) uses modifyAddressLo
This is also where the xTrackSegmentI table is built, once the modifications have been done. The block is padded out to be exactly 20 bytes long, so along with the modifyAddressHi block, there's one byte for each inner segment x-coordinate..modifyAddressHi EQUB &12 \ !&1249 = HookSectionFrom EQUB &12 \ !&128A = HookFirstSegment EQUB &13 \ !&13CA = HookSegmentVector EQUB &14 \ !&1427 = HookSegmentVector EQUB &12 \ !&12FC = HookDataPointers EQUB &26 \ !&261B = HookUpdateHorizon EQUB &24 \ !&248C = HookFieldOfView EQUB &25 \ !&2539 = HookFixHorizon EQUB &15 \ !&1594 = HookJoystick EQUB &4C \ !&4CD1 = xTrackSignVector EQUB &4C \ !&4CC9 = yTrackSignVector EQUB &4C \ !&4CC1 = zTrackSignVector EQUB &44 \ !&44D6 = trackSteering EQUB &4C \ !&4CD7 = trackSignData EQUB &4C \ !&4CE1 = trackSignData EQUB &19 \ !&1947 = HookFlattenHills EQUB &24 \ !&24F3 = HookMoveBack EQUB &46 \ !&462C = HookFlipAbsolute EQUB &25 \ !&2543 = Hook80Percent EQUB &00 \ This byte pads the block out to exactly 20 bytesName: modifyAddressHi [Show more] Type: Variable Category: Extra tracks Summary: High byte of the location in the main game code where we modify a two-byte addressContext: See this variable on its own page References: This variable is used as follows: * ModifyGameCode (Part 1 of 3) uses modifyAddressHi
This is also where the xTrackSegmentI table is built, once the modifications have been done. The block is padded out to be exactly 20 bytes long, so along with the modifyAddressLo block, there's one byte for each inner segment x-coordinate..trackYawDeltaHi EQUB &00 \ Sub-section 0 = &0023 ( 35) EQUB &00 \ Sub-section 1 = &0048 ( 72) EQUB &00 \ Sub-section 2 = &00CB ( 203) EQUB &01 \ Sub-section 3 = &01AC ( 428) EQUB &05 \ Sub-section 4 = &055C ( 1372) EQUB &01 \ Sub-section 5 = &019D ( 413) EQUB &00 \ Sub-section 6 = &0000 ( 0) EQUB &02 \ Sub-section 7 = &02AB ( 683) EQUB &00 \ Sub-section 8 = &0000 ( 0) EQUB &00 \ Sub-section 9 = &0000 ( 0) EQUB &00 \ Sub-section 10 = &0000 ( 0) EQUB &06 \ Sub-section 11 = &063D ( 1597) EQUB &00 \ Sub-section 12 = &0000 ( 0) EQUB &FC \ Sub-section 13 = &FC0A (-1014) EQUB &FD \ Sub-section 14 = &FDDE ( -546) EQUB &FC \ Sub-section 15 = &FC17 (-1001) EQUB &FE \ Sub-section 16 = &FEF8 ( -264) EQUB &FF \ Sub-section 17 = &FF4A ( -182) EQUB &FF \ Sub-section 18 = &FFE1 ( -31) EQUB &FF \ Sub-section 19 = &FF16 ( -234) EQUB &FD \ Sub-section 20 = &FD46 ( -698) EQUB &FE \ Sub-section 21 = &FE52 ( -430) EQUB &FD \ Sub-section 22 = &FD5C ( -676) EQUB &FB \ Sub-section 23 = &FBBC (-1092) EQUB &00 \ Sub-section 24 = &0000 ( 0) EQUB &00 \ Sub-section 25 = &0000 ( 0) EQUB &00 \ Sub-section 26 = &0000 ( 0) EQUB &01 \ Sub-section 27 = &016C ( 364) EQUB &00 \ Sub-section 28 = &0000 ( 0) EQUB &00 \ Sub-section 29 = &0000 ( 0) EQUB &00 \ Sub-section 30 = &0000 ( 0) EQUB &00 \ Sub-section 31 = &0000 ( 0) EQUB &00 \ Sub-section 32 = &0000 ( 0) EQUB &01 \ Sub-section 33 = &0132 ( 306) EQUB &01 \ Sub-section 34 = &019A ( 410) EQUB &01 \ Sub-section 35 = &01FB ( 507) EQUB &04 \ Sub-section 36 = &0417 ( 1047) EQUB &01 \ Sub-section 37 = &01A3 ( 419) EQUB &03 \ Sub-section 38 = &0311 ( 785) EQUB &01 \ Sub-section 39 = &015A ( 346) EQUB &00 \ Sub-section 40 = &0000 ( 0) EQUB &00 \ Sub-section 41 = &0000 ( 0) EQUB &02 \ Sub-section 42 = &0272 ( 626) EQUB &03 \ Sub-section 43 = &037C ( 892) EQUB &05 \ Sub-section 44 = &057A ( 1402) EQUB &FC \ Sub-section 45 = &FCBB ( -837) EQUB &FB \ Sub-section 46 = &FBF8 (-1032) EQUB &00 \ Sub-section 47 = &0000 ( 0) EQUB &00 \ Sub-section 48 = &0000 ( 0) EQUB &00 \ Sub-section 49 = &0000 ( 0) EQUB &00 \ Sub-section 50 = &0000 ( 0) EQUB &05 \ Sub-section 51 = &0555 ( 1365) EQUB &02 \ Sub-section 52 = &0211 ( 529) EQUB &02 \ Sub-section 53 = &0211 ( 529) EQUB &00 \ Sub-section 54 = &0060 ( 96) EQUB &01 \ Sub-section 55 = &01B0 ( 432) EQUB &00 \ Sub-section 56 = &0078 ( 120) EQUB &00 \ Sub-section 57 = &0020 ( 32)Name: trackYawDeltaHi [Show more] Type: Variable Category: Extra tracks Summary: High byte of the change in yaw angle that we apply to each segment in the specified sub-section when building the trackContext: See this variable on its own page References: This variable is used as follows: * SetSegmentVector uses trackYawDeltaHi.trackSignData EQUB %00001100 \ Sign 0: 00001 100 Type 11 Right turn Section 1 EQUB %00010000 \ Sign 1: 00010 000 Type 7 Straight Section 2 EQUB %00100011 \ Sign 2: 00100 011 Type 10 Hairpin Section 4 EQUB %00100000 \ Sign 3: 00100 000 Type 7 Straight Section 4 EQUB %00111000 \ Sign 4: 00111 000 Type 7 Straight Section 7 EQUB %01001101 \ Sign 5: 01001 101 Type 12 Left turn Section 9 EQUB %01011000 \ Sign 6: 01011 000 Type 7 Straight Section 11 EQUB %01100000 \ Sign 7: 01100 000 Type 7 Straight Section 12 EQUB %01101100 \ Sign 8: 01101 100 Type 11 Right turn Section 13 EQUB %10001100 \ Sign 9: 10001 100 Type 11 Right turn Section 17 EQUB %10100100 \ Sign 10: 10100 100 Type 11 Right turn Section 20 EQUB %10110101 \ Sign 11: 10110 101 Type 12 Left turn Section 22 EQUB %11000000 \ Sign 12: 11000 000 Type 7 Straight Section 24 EQUB %11010100 \ Sign 13: 11010 100 Type 11 Right turn Section 26 EQUB %11100000 \ Sign 14: 11100 000 Type 7 Straight Section 28 EQUB %00000001 \ Sign 15: 00000 001 Type 8 Start flag Section 0Name: trackSignData [Show more] Type: Variable Category: Track data Summary: Base coordinates and object types for 16 road signs Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: This variable is used as follows: * newContentHi uses trackSignData * newContentLo uses trackSignData.CalcSegmentVector \ This routine calculates the segment vector for the \ current segment within the current sub-section \ \ The segment vector contains two vectors: \ \ * (xTrackSegmentI yTrackSegmentI zTrackSegmentI) is \ the vector along the inside of the track from the \ previous segment to the current segment \ \ * (xTrackSegmentO yTrackSegmentI zTrackSegmentO) is \ the vector from the inner edge of the track to the \ outer edge of the track for the current segment \ \ We start by analysing the track's yaw angle to see in \ which direction the track that we're building is \ currently pointing, so we can set the correct signs \ and axes for the segment vector LDA yawAngleLo \ Set A = (yawAngleHi yawAngleLo) << 1 ASL A \ LDA yawAngleHi \ Keeping the high byte only and rotating bit 7 into ROL A \ the C flag PHA \ Push the high byte in A onto the stack, so the stack \ contains the high byte of yawAngle << 1 ROL A \ Set bits 0-2 of U to bits 5-7 of yawAngleHi (i.e. the ROL A \ top three bits), so this is equivalent to: ROL A \ AND #%00000111 \ U = (yawAngleHi yawAngleLo) DIV 8192 STA U \ \ We will use U to work out the direction of the track \ that we are building \ We now work out the index into the xTrackCurve and \ zTrackCurve tables for the curve that matches the \ direction of the track, putting the result in X \ \ The curve tables contain coordinates for a curve that \ covers one-eighth of a circle, or 45 degrees, so we \ first reduce the yaw angle into that range by reducing \ our 32-bit angle into this range \ \ The 32-bit angle in (yawAngleHi yawAngleLo) cover a \ whole circle, so 0 to 65536 represents 0 to 360 \ degrees, so one-eighth of a circle, or 45 degrees, is \ represented by 65536 / 8 = 8192 \ \ So we reduce the 32-bit value into the range 0 to 8192 \ so we can map it to the curve in the curve tables LSR A \ Set the C flag to bit 0 of A, i.e. bit 5 of yawAngleHi PLA \ Retrieve the high byte that we pushed onto the stack, \ i.e. the high byte of yawAngle << 1 AND #%00111111 \ Clear bits 6 and 7 of A, so A now contains two zeroes, \ then bits 4, 3, 2, 1, 0 of yawAngleHi, then bit 7 of \ yawAngleLo \ By this point, we have: \ \ X = (yawAngleHi yawAngleLo) MOD 8192 \ \ This is the corresponding point in the curve tables \ for the track direction, reduced to one-eighth of a \ circle, or 0 to 45 degrees \ \ The next eighth of the circle (i.e. from 45 to 90 \ degrees) will map to the curve tables, but in reverse, \ so we can extend our calculation to quarter circle by \ flipping the index in X for this range of yaw angle \ (i.e. if we are in the second eighth of the circle, \ from 45 to 90 degrees, which is when bit 5 of the high \ byte is clear) BCC vect1 \ If the C flag, i.e. bit 5 of yawAngleHi, is clear, \ jump to vect1 to skip the following EOR #%00111111 \ Negate A using two's complement (the ADC adds 1 as the ADC #0 \ C flag is set) .vect1 \ By this point, A contains the index of the curve \ within the curve tables that corresponds to the angle \ in which the track is pointing, reduced to the first \ quarter of a circle (0 to 90 degrees) \ \ We can now fetch the vector for that point on the \ curve, which will give us the vector of the curve at \ that point (i.e. the direction of the curve for the \ track segment we are building) TAX \ Set X = A LDY xTrackCurve,X \ Set Y = X-th entry in xTrackCurve LDA zTrackCurve,X \ Set X = X-th entry in zTrackCurve TAX \ The vector in X and Y now contains the correct values \ for the curve vector, but because we reduced it to the \ first quarter in the circle, the signs may not be \ correct, and we may need to swap the x-coordinate and \ z-coordinate \ \ We now use the value of U to set the vector properly, \ as the value of U determines which eighth of the \ circle corresponds to the track direction LDA U \ If bit 1 of U + 1 is set, i.e. U ends in %01 or %10, CLC \ i.e. bits 5 and 6 of yawAngleHi are different, then ADC #1 \ jump to vect2 to set V and W the other way round AND #%00000010 BNE vect2 STY V \ Set V = Y STX W \ Set W = X BEQ vect3 \ Jump to vect3 (this BEQ is effectively a JMP as we \ passed through a BNE above) .vect2 STX V \ Set V = X STY W \ Set W = Y .vect3 LDA U \ If U < 4, i.e. bit 2 of U is clear, i.e. bit 7 of CMP #4 \ yawAngleHi is clear, jump to vect4 to skip the BCC vect4 \ following \ If we get here then bit 2 of U is set, i.e. bit 7 of \ yawAngleHi is set LDA #0 \ Set V = -V SBC V STA V .vect4 LDA U \ If U >= 6, i.e. bits 1 and 2 of U are set, i.e. bits CMP #6 \ 6 and 7 of yawAngleHi are set, jump to vect5 to skip BCS vect5 \ the following CMP #2 \ If U < 2, i.e. bits 1 and 2 of U are clear, i.e. bits BCC vect5 \ 6 and 7 of yawAngleHi are clear, jump to vect5 to skip \ the following \ If we get here then bits 1 and 2 of U are different, \ i.e. bits 6 and 7 of yawAngleHi are different LDA #0 \ Set W = -W SBC W STA W .vect5 \ By this point we have the x- and z-coordinates of the \ vector for the track direction in the segment that we \ want to build, and we already know the y-coordinate of \ the vector at this point (it's in segmentSlope) \ \ The inner track segment vector at this point is \ therefore: \ \ [ V ] \ [ segmentSlope ] \ [ W ] \ \ And we can now store the vector in the track data file \ as follows: \ \ * xTrackSegmentI = V \ * yTrackSegmentI = segmentSlope \ * zTrackSegmentI = W \ \ We can also calculate the vector from the inner verge \ to the outer verge as follows: \ \ * xTrackSegmentO = -W * trackWidth / 256 \ * zTrackSegmentO = V * trackWidth / 256 \ \ This works because given a 2D vector [V W], the vector \ [-W V] is the vector's normal, i.e. the same vector, \ but perpendicular to the original \ \ If we take the original inner vector in [V W], then \ its normal vector is a vector that's perpendicular to \ the original, so instead of being a vector pointing \ along the inner edge, it's a vector pointing at 90 \ degrees across the track, which is the vector that we \ want to calculate \ \ Multiplying the normal vector by the track width sets \ the correct length for the outer segment vector, so \ we could make the track wider by changing the value of \ the trackWidth configuration variable LDY thisVectorNumber \ Set Y to thisVectorNumber, which contains the value of \ trackSectionFrom for this track section (i.e. the \ number of the first segment vector in the section) LDA #trackWidth \ Set U to the width of the track STA U LDA V \ Set the x-coordinate of the Y-th inner track segment STA xTrackSegmentI,Y \ vector to V JSR Multiply8x8Signed \ Set A = A * U / 256 \ = V * trackWidth / 256 STA zTrackSegmentO,Y \ Set the z-coordinate of the Y-th outer track segment \ vector to V * trackWidth / 256 LDA W \ Set the z-coordinate of the Y-th inner track segment STA zTrackSegmentI,Y \ vector to W JSR Multiply8x8Signed \ Set A = A * U / 256 \ = W * trackWidth / 256 EOR #&FF \ Negate A using two's complement, so: CLC \ ADC #1 \ A = -W * trackWidth / 256 STA xTrackSegmentO,Y \ Set the x-coordinate of the Y-th outer track segment \ vector to -W * trackWidth / 256 LDA segmentSlope \ Set the y-coordinate of the Y-th track segment vector STA yTrackSegmentI,Y \ to the slope of the segment RTS \ Return from the subroutineName: CalcSegmentVector [Show more] Type: Subroutine Category: Extra tracks Summary: Calculate the segment vector for the current segment Deep dive: Dynamic track generation in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * HookFirstSegment calls CalcSegmentVector * SetSegmentVector calls CalcSegmentVector
This routine calculates the segment vector for the current segment, by converting the direction of the track at this point, which is stored in the yaw angle in (yawAngleHi yawAngleLo), into a direction vector to store in the (xTrackSegmentI yTrackSegmentI zTrackSegmentI) tables in the track data file. We also calculate the outer track segment vector (i.e. the vector across the track) and store it in the (xTrackSegmentO yTrackSegmentI zTrackSegmentO) tables in the track data file. Note that the track segment vector tables overwrite the modification routines, as those are no longer used, and the main game code still thinks that's where the segment vector tables are stored as part of the track data file (which they are, it's just that they are dynamically generated in the extra track files, rather than being full of static data)..HookFlipAbsolute EOR directionFacing \ Flip the sign bit of A if we are facing backwards \ along the track \ \ The Absolute8Bit routine does the following: \ \ * If A is positive leave it alone \ \ * If A is negative, set A = -A \ \ So if bit 7 of directionFacing is set (i.e. we are \ facing backwards along the track), this flips bit 7 of \ A, which changes the Absolute8Bit routine to the \ following (if we consider the original value of A): \ \ * If A is negative leave it alone \ \ * If A is positive, set A = -A \ \ So this sets set A = -|A| instead of A = |A| JSR Absolute8Bit \ Set A = |A|, unless we are facing backwards along the \ track, in which case set A = -|A| RTS \ Return from the subroutineName: HookFlipAbsolute [Show more] Type: Subroutine Category: Extra tracks Summary: Set the sign of A according to the direction we are facing along the track Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookFlipAbsolute * newContentLo calls HookFlipAbsolute
This routine is called from MovePlayerOnTrack so that the yaw angle of the closest segment retains the correct sign, like this: * If we are facing forwards along the track, set A = |A| * If we are facing backwards along the track, set A = -|A|.HookDataPointers LDA thisSectionFlags \ If bit 6 of the current section's flags is clear, jump AND #%01000000 \ to flab1 to skip the following call, so we just BEQ flab1 \ implement the same code as in the original JSR UpdateDataPointers \ Bit 6 of the current section's flags is set, so we are \ generating this section's segment vectors using the \ curve tables, so call UpdateDataPointers to update \ the pointers to the next sub-section and segment along \ the track, before continuing with the same code as in \ the original .flab1 LDA frontSegmentIndex \ Set A to the index * 3 of the front track segment in \ the track segment buffer CLC \ Set A = frontSegmentIndex + 3 ADC #3 \ \ to move on to the next track segment ahead of the \ current front segment in the track segment buffer, \ which will become the new front segment RTS \ Return from the subroutineName: HookDataPointers [Show more] Type: Subroutine Category: Extra tracks Summary: If the current section is dynamically generated, update the data pointers Deep dive: Secrets of the extra tracks Dynamic track generation in the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookDataPointers * newContentLo calls HookDataPointers
This routine is called from part 1 of GetTrackSegment so we update the sub-section and sub-section segment pointers when fetching a new track segment. If bit 6 of the current section's flags is set, then the track segment vectors for this section need to be generated from the curve tables (as opposed to being calculated as a straight section). When this is the case, this routine calls UpdateDataPointers to update the pointers to the next sub-section and segment along the track..newContentLo EQUB LO(HookSectionFrom) EQUB LO(HookFirstSegment) EQUB LO(HookSegmentVector) EQUB LO(HookSegmentVector) EQUB LO(HookDataPointers) EQUB LO(HookUpdateHorizon) EQUB LO(HookFieldOfView) EQUB LO(HookFixHorizon) EQUB LO(HookJoystick) EQUB LO(xTrackSignVector) EQUB LO(yTrackSignVector) EQUB LO(zTrackSignVector) EQUB LO(trackSteering) EQUB LO(trackSignData) EQUB LO(trackSignData) EQUB LO(HookFlattenHills) EQUB LO(HookMoveBack) EQUB LO(HookFlipAbsolute) EQUB LO(Hook80Percent) EQUB &00 \ This byte pads the block out to exactly 20 bytesName: newContentLo [Show more] Type: Variable Category: Extra tracks Summary: Low byte of the two-byte address that we want to poke into the main game code at the modify locationContext: See this variable on its own page References: This variable is used as follows: * ModifyGameCode (Part 1 of 3) uses newContentLo
This is also where the zTrackSegmentI table is built, once the modifications have been done. The block is padded out to be exactly 20 bytes long, so along with the newContentHi block, there's one byte for each inner segment z-coordinate..newContentHi EQUB HI(HookSectionFrom) EQUB HI(HookFirstSegment) EQUB HI(HookSegmentVector) EQUB HI(HookSegmentVector) EQUB HI(HookDataPointers) EQUB HI(HookUpdateHorizon) EQUB HI(HookFieldOfView) EQUB HI(HookFixHorizon) EQUB HI(HookJoystick) EQUB HI(xTrackSignVector) EQUB HI(yTrackSignVector) EQUB HI(zTrackSignVector) EQUB HI(trackSteering) EQUB HI(trackSignData) EQUB HI(trackSignData) EQUB HI(HookFlattenHills) EQUB HI(HookMoveBack) EQUB HI(HookFlipAbsolute) EQUB HI(Hook80Percent) EQUB &00 \ This byte pads the block out to exactly 20 bytesName: newContentHi [Show more] Type: Variable Category: Extra tracks Summary: High byte of the two-byte address that we want to poke into the main game code at the modify locationContext: See this variable on its own page References: This variable is used as follows: * ModifyGameCode (Part 1 of 3) uses newContentHi
This is also where the zTrackSegmentI table is built, once the modifications have been done. The block is padded out to be exactly 20 bytes long, so along with the newContentLo block, there's one byte for each inner segment z-coordinate..trackYawDeltaLo EQUB &23 \ Sub-section 0 = &0023 ( 35) EQUB &48 \ Sub-section 1 = &0048 ( 72) EQUB &CB \ Sub-section 2 = &00CB ( 203) EQUB &AC \ Sub-section 3 = &01AC ( 428) EQUB &5C \ Sub-section 4 = &055C ( 1372) EQUB &9D \ Sub-section 5 = &019D ( 413) EQUB &00 \ Sub-section 6 = &0000 ( 0) EQUB &AB \ Sub-section 7 = &02AB ( 683) EQUB &00 \ Sub-section 8 = &0000 ( 0) EQUB &00 \ Sub-section 9 = &0000 ( 0) EQUB &00 \ Sub-section 10 = &0000 ( 0) EQUB &3D \ Sub-section 11 = &063D ( 1597) EQUB &00 \ Sub-section 12 = &0000 ( 0) EQUB &0A \ Sub-section 13 = &FC0A (-1014) EQUB &DE \ Sub-section 14 = &FDDE ( -546) EQUB &17 \ Sub-section 15 = &FC17 (-1001) EQUB &F8 \ Sub-section 16 = &FEF8 ( -264) EQUB &4A \ Sub-section 17 = &FF4A ( -182) EQUB &E1 \ Sub-section 18 = &FFE1 ( -31) EQUB &16 \ Sub-section 19 = &FF16 ( -234) EQUB &46 \ Sub-section 20 = &FD46 ( -698) EQUB &52 \ Sub-section 21 = &FE52 ( -430) EQUB &5C \ Sub-section 22 = &FD5C ( -676) EQUB &BC \ Sub-section 23 = &FBBC (-1092) EQUB &00 \ Sub-section 24 = &0000 ( 0) EQUB &00 \ Sub-section 25 = &0000 ( 0) EQUB &00 \ Sub-section 26 = &0000 ( 0) EQUB &6C \ Sub-section 27 = &016C ( 364) EQUB &00 \ Sub-section 28 = &0000 ( 0) EQUB &00 \ Sub-section 29 = &0000 ( 0) EQUB &00 \ Sub-section 30 = &0000 ( 0) EQUB &00 \ Sub-section 31 = &0000 ( 0) EQUB &00 \ Sub-section 32 = &0000 ( 0) EQUB &32 \ Sub-section 33 = &0132 ( 306) EQUB &9A \ Sub-section 34 = &019A ( 410) EQUB &FB \ Sub-section 35 = &01FB ( 507) EQUB &17 \ Sub-section 36 = &0417 ( 1047) EQUB &A3 \ Sub-section 37 = &01A3 ( 419) EQUB &11 \ Sub-section 38 = &0311 ( 785) EQUB &5A \ Sub-section 39 = &015A ( 346) EQUB &00 \ Sub-section 40 = &0000 ( 0) EQUB &00 \ Sub-section 41 = &0000 ( 0) EQUB &72 \ Sub-section 42 = &0272 ( 626) EQUB &7C \ Sub-section 43 = &037C ( 892) EQUB &7A \ Sub-section 44 = &057A ( 1402) EQUB &BB \ Sub-section 45 = &FCBB ( -837) EQUB &F8 \ Sub-section 46 = &FBF8 (-1032) EQUB &00 \ Sub-section 47 = &0000 ( 0) EQUB &00 \ Sub-section 48 = &0000 ( 0) EQUB &00 \ Sub-section 49 = &0000 ( 0) EQUB &00 \ Sub-section 50 = &0000 ( 0) EQUB &55 \ Sub-section 51 = &0555 ( 1365) EQUB &11 \ Sub-section 52 = &0211 ( 529) EQUB &11 \ Sub-section 53 = &0211 ( 529) EQUB &60 \ Sub-section 54 = &0060 ( 96) EQUB &B0 \ Sub-section 55 = &01B0 ( 432) EQUB &78 \ Sub-section 56 = &0078 ( 120) EQUB &20 \ Sub-section 57 = &0020 ( 32)Name: trackYawDeltaLo [Show more] Type: Variable Category: Extra tracks Summary: Low byte of the change in yaw angle that we apply to each segment in the specified sub-section when building the trackContext: See this variable on its own page References: This variable is used as follows: * SetSegmentVector uses trackYawDeltaLo.xTrackSignVector EQUB -16 \ Sign 0 = (-16 << 6, 26 << 4, -46 << 6) + section 0 EQUB -42 \ Sign 1 = (-42 << 6, 76 << 4, 4 << 6) + section 2 EQUB -40 \ Sign 2 = (-40 << 6, -39 << 4, 28 << 6) + section 3 EQUB 12 \ Sign 3 = ( 12 << 6, -26 << 4, -20 << 6) + section 5 EQUB 9 \ Sign 4 = ( 9 << 6, 13 << 4, 10 << 6) + section 7 EQUB -2 \ Sign 5 = ( -2 << 6, 8 << 4, -21 << 6) + section 9 EQUB -10 \ Sign 6 = (-10 << 6, -20 << 4, -9 << 6) + section 12 EQUB 50 \ Sign 7 = ( 50 << 6, 6 << 4, 45 << 6) + section 14 EQUB 28 \ Sign 8 = ( 28 << 6, -32 << 4, 27 << 6) + section 14 EQUB -33 \ Sign 9 = (-33 << 6, 16 << 4, 43 << 6) + section 14 EQUB -12 \ Sign 10 = (-12 << 6, 18 << 4, -8 << 6) + section 18 EQUB -14 \ Sign 11 = (-14 << 6, 5 << 4, 16 << 6) + section 19 EQUB -8 \ Sign 12 = ( -8 << 6, 30 << 4, -14 << 6) + section 20 EQUB 51 \ Sign 13 = ( 51 << 6, 1 << 4, 41 << 6) + section 21 EQUB 13 \ Sign 14 = ( 13 << 6, -6 << 4, -20 << 6) + section 22 EQUB -4 \ Sign 15 = ( -4 << 6, 8 << 4, 0 << 6) + section 23Name: xTrackSignVector [Show more] Type: Variable Category: Extra tracks Summary: The x-coordinate of the track sign vector for each sign, to be scaled and added to the inner track section vector for the signContext: See this variable on its own page References: This variable is used as follows: * newContentHi uses xTrackSignVector * newContentLo uses xTrackSignVector.HookSegmentVector LDA thisSectionFlags \ If bit 6 of the current section's flags is clear, jump AND #%01000000 \ to flag1 to return from the subroutine BEQ flag1 \ Bit 6 of the current section's flags is set, so we are \ generating this section's segment vectors using the \ curve tables JSR UpdateVectorNumber \ Update thisVectorNumber to the next segment vector \ along the track in the direction we are facing (we \ replaced a call to UpdateCurveVector with the call to \ the hook, so this implements that call, knowing that \ this is a curve) JSR SetSegmentVector \ Calculate and store the next segment vector, so it can \ be read by the main game code as if it were a static \ piece of data from a normal track data file .flag1 RTS \ Return from the subroutineName: HookSegmentVector [Show more] Type: Subroutine Category: Extra tracks Summary: If the current section is dynamically generated, move to the next segment vector, calculate it and store it Deep dive: Secrets of the extra tracks Dynamic track generation in the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookSegmentVector * newContentLo calls HookSegmentVector
This routine is called from part 3 of GetTrackSegment and TurnPlayerAround, so we calculate the next track segment vector on-the-fly for curved sections. If bit 6 of the current section's flags is set, then the track segment vectors for this section need to be generated from the curve tables (as opposed to being calculated as a straight section). When this is the case, this routine calls UpdateVectorNumber and SetSegmentVector to calculate and store the next track segment vector, which can then be read by the main game code as if it were a static piece of data from a normal track data file..MoveToNextVector JSR UpdateVectorNumber \ Update thisVectorNumber to the next segment vector \ along the track in the direction we are facingName: MoveToNextVector [Show more] Type: Subroutine Category: Extra tracks Summary: Move to the next to the next segment vector along the track and update the pointersContext: See this subroutine on its own page References: This subroutine is called as follows: * HookFirstSegment calls MoveToNextVector.UpdateDataPointers LDY subSection \ Set Y to the number of the current sub-section within \ the current track section LDA subSectionSegment \ Set A to the number of the current segment within the \ current sub-section SEC \ Set the C flag for use in the following addition or \ subtraction BIT directionFacing \ If we are facing backwards along the track, jump to BMI upda1 \ upda1 to move to the next segment in that direction \ If we get here then we are facing forwards along the \ track, so we increment subSectionSegment to point to \ the next segment \ \ If subSectionSegment reaches trackSubSize for this \ sub-section, then we have reached the end of that \ sub-section and need to start the next sub-section, \ so we wrap the segment number within the sub-section \ round to zero and increment subSection to move on to \ the next sub-section \ \ If subSection then reaches trackSubCount, which is the \ total number of sub-sections in the track, then we \ have reached the end of the last sub-section, so we \ wrap subSection round to zero ADC #0 \ Set A = A + 1 \ = subSectionSegment + 1 \ \ This works as the C flag is set CMP trackSubSize,Y \ If A < trackSubSize for this index, jump to upda3 to BCC upda3 \ update the pointers and return from the subroutine LDA #0 \ Set A = 0, to set as the new segment number in \ subSectionSegment within the next sub-section INY \ Increment Y to point to the next sub-section CPY trackSubCount \ If Y < trackSubCount, jump to upda3 to update the BCC upda3 \ pointers and return from the subroutine LDY #0 \ Set Y = 0, to set the new value of subSection to the \ start of the data BEQ upda3 \ Jump to upda3 to update the pointers and return from \ the subroutine (this BEQ is effectively a JMP as Y is \ always zero) .upda1 \ If we get here then we are facing backwards along the \ track, so we decrement subSectionSegment to point to \ the previous segment, i.e. backwards along the track \ \ If subSectionSegment goes past 0, then we have gone \ past the start of that sub-section and need to jump to \ the end of the previous sub-section, so we wrap the \ segment number within the sub-section to the last \ segment number in the previous sub-section and \ decrement subSection to move back to the previous \ sub-section \ \ If subSection reaches 0, which is the start of the \ track, then we wrap it round to the last sub-section \ to go backwards past the start to reach the end of the \ track SBC #1 \ Set A = A - 1 \ = subSectionSegment - 1 \ \ This works as the C flag is set BCS upda3 \ If the subtraction didn't underflow, jump to upda3 to \ update the pointers and return from the subroutine \ If we get here, then subSectionSegment has just gone \ past 0, so we need to jump to the end of the previous \ sub-section TYA \ Clear bit 7 of Y to ensure that Y is positive AND #%01111111 TAY CPY #1 \ If Y >= 1, jump to upda2 as we aren't about to go past BCS upda2 \ the start of the first sub-section \ If we get here then Y = 0, so we are in the first \ segment of the first sub-section, so we need to wrap \ the sub-section around to the end of the track LDY trackSubCount \ Set Y = trackSubCount, so we set the new value of \ subSection to trackSubCount - 1, i.e. the last \ sub-section in the track .upda2 DEY \ Decrement Y to point to the previous sub-section LDA trackSubSize,Y \ Set A to trackSubSize - 1 for this index, which points SEC \ to the last entry in the new sub-section SBC #1 .upda3 STA subSectionSegment \ Update the segment number within the sub-section to \ the updated value of A STY subSection \ Update the sub-section to the updated value of Y RTS \ Return from the subroutineName: UpdateDataPointers [Show more] Type: Subroutine Category: Extra tracks Summary: Update the sub-section and segment numbers to point to the next segment along the track in the correct directionContext: See this subroutine on its own page References: This subroutine is called as follows: * HookDataPointers calls UpdateDataPointers.HookMoveBack BIT playerPastSegment \ If bit 7 of playerPastSegment is set, return from the BMI HookMoveBack-1 \ subroutine (as HookMoveBack-1 contains an RTS) JMP MovePlayerBack \ Move the player backwards by one segment, returning \ from the subroutine using a tail callName: HookMoveBack [Show more] Type: Subroutine Category: Extra tracks Summary: Only move the player backwards if the player has not yet driven past the segment Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookMoveBack * newContentLo calls HookMoveBack
This routine is called from MovePlayerSegment to change the behaviour when moving the player backwards along the track. Only move the player backwards by one segment if bit 7 of playerPastSegment is clear (in other words, if the player has not yet driven past the segment)..SetSegmentVector STX xStore \ Store X in xStore so we can retrieve it at the end of \ the routine LDY subSection \ Set Y to the number of the current sub-section within \ the current track section BMI sets1 \ If bit 7 of Y is set, then this part of the track is a \ straight section that doesn't use the curve vectors to \ generate the track, so jump to sets1 to skip updating \ the yaw angle and track height, as we simply reuse the \ same track segment vector for each segment within the \ straight \ We start by adding the yaw delta to the yaw angle LDA trackYawDeltaLo,Y \ Set (A T) = (trackYawDeltaHi trackYawDeltaLo) for this STA T \ sub-section LDA trackYawDeltaHi,Y BIT directionFacing \ Set the N flag to the sign of directionFacing, so the \ call to Absolute16Bit sets the sign of (A T) to \ abs(directionFacing) JSR Absolute16Bit \ Set the sign of (A T) to match the sign bit in \ directionFacing, so this negates (A T) if we are \ facing backwards along the track STA U \ Set (U T) = (A T) \ = signed (trackYawDeltaHi trackYawDeltaLo) \ for this sub-section LDA T \ Set yawAngle = yawAngle + (U T) CLC \ = yawAngle + trackYawDelta ADC yawAngleLo \ STA yawAngleLo \ starting with the low bytes LDA U \ And then the high bytes ADC yawAngleHi STA yawAngleHi \ And now we add the track gradient (i.e. the height \ delta) to the track height LDA trackSlopeDelta,Y \ Set A to the change in slope for this sub-section \ (i.e. the change in the gradient over the course of \ each segment in the sub-section) BIT directionFacing \ Set the N flag to the sign of directionFacing, so the \ call to Absolute8Bit sets the sign of A to \ abs(directionFacing) JSR Absolute8Bit \ Set the sign of A to match the sign bit in \ directionFacing, so this negates A if we are facing \ backwards along the track CLC \ Set segmentSlope = segmentSlope + A ADC segmentSlope \ = segmentSlope + trackSlopeDelta STA segmentSlope .sets1 JSR CalcSegmentVector \ Calculate the segment vector for the current segment \ and put it in the xSegmentVectorI, ySegmentVectorI, \ zSegmentVectorI, xSegmentVectorO and zSegmentVectorO \ tables LDX xStore \ Retrieve the value of X we stores above, so we can \ return it unchanged by the routine RTS \ Return from the subroutineName: SetSegmentVector [Show more] Type: Subroutine Category: Extra tracks Summary: Add the yaw angle and height deltas to the yaw angle and height (for curved sections) and calculate the segment vector Deep dive: Dynamic track generation in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * HookSectionFrom calls SetSegmentVector * HookSegmentVector calls SetSegmentVector
This routine adds the yaw angle and height deltas to the track yaw angle and height, to get the coordinates for the next segment along. It then calls the CalcSegmentVector routine to calculate the segment vectors and store them in the correct tables for the main game code to read. If the current sub-section number has bit 7 set, then this section isn't being generated using the curve tables, but is instead being generated as a straight part of the track. In this case we don't update the yaw angle or track height before calculating the segment vector, as the main game code draws straight segments by simply adding the same track segment vector for each segment in the straight..mods3 LDA #4 \ ?&3574 = 4 (object dimension in objectTop) STA &3574 LDA #11 \ ?&35F4 = 11 (object dimension in objectBottom) STA &35F4 LDA #LO(HookSlopeJump) \ !&45CC = HookSlopeJump (address in a JSR instruction) STA &45CC LDA #HI(HookSlopeJump) STA &45CD LDA #75 \ ?&2772 = 75 (argument in a CMP #75 instruction) STA &2772 RTS \ Return from the subroutine EQUB &00, &00 \ These bytes pad the routine out to exactly 40 bytes EQUB &00, &00 EQUB &00, &00 EQUB &00, &00 EQUB &00, &00 EQUB &00, &00 EQUB &00, &00Name: ModifyGameCode (Part 3 of 3) [Show more] Type: Subroutine Category: Extra tracks Summary: Modify the game code to support the extra track dataContext: See this subroutine on its own page References: No direct references to this subroutine in this source file
The code modifications are done in three parts. This is also where the zTrackSegmentI table is built, once the modifications have been done. The routine is padded out to be exactly 40 bytes long, so there's one byte for each inner segment z-coordinate..trackSlopeDelta EQUB &01 \ Sub-section 0 = 1 EQUB &FE \ Sub-section 1 = -2 EQUB &FF \ Sub-section 2 = -1 EQUB &FE \ Sub-section 3 = -2 EQUB &FF \ Sub-section 4 = -1 EQUB &00 \ Sub-section 5 = 0 EQUB &04 \ Sub-section 6 = 4 EQUB &09 \ Sub-section 7 = 9 EQUB &00 \ Sub-section 8 = 0 EQUB &F9 \ Sub-section 9 = -7 EQUB &F9 \ Sub-section 10 = -7 EQUB &00 \ Sub-section 11 = 0 EQUB &00 \ Sub-section 12 = 0 EQUB &00 \ Sub-section 13 = 0 EQUB &04 \ Sub-section 14 = 4 EQUB &00 \ Sub-section 15 = 0 EQUB &00 \ Sub-section 16 = 0 EQUB &00 \ Sub-section 17 = 0 EQUB &00 \ Sub-section 18 = 0 EQUB &00 \ Sub-section 19 = 0 EQUB &03 \ Sub-section 20 = 3 EQUB &02 \ Sub-section 21 = 2 EQUB &02 \ Sub-section 22 = 2 EQUB &01 \ Sub-section 23 = 1 EQUB &00 \ Sub-section 24 = 0 EQUB &FA \ Sub-section 25 = -6 EQUB &00 \ Sub-section 26 = 0 EQUB &00 \ Sub-section 27 = 0 EQUB &00 \ Sub-section 28 = 0 EQUB &FD \ Sub-section 29 = -3 EQUB &03 \ Sub-section 30 = 3 EQUB &04 \ Sub-section 31 = 4 EQUB &01 \ Sub-section 32 = 1 EQUB &FF \ Sub-section 33 = -1 EQUB &FE \ Sub-section 34 = -2 EQUB &FE \ Sub-section 35 = -2 EQUB &01 \ Sub-section 36 = 1 EQUB &00 \ Sub-section 37 = 0 EQUB &00 \ Sub-section 38 = 0 EQUB &00 \ Sub-section 39 = 0 EQUB &FC \ Sub-section 40 = -4 EQUB &02 \ Sub-section 41 = 2 EQUB &03 \ Sub-section 42 = 3 EQUB &FD \ Sub-section 43 = -3 EQUB &FD \ Sub-section 44 = -3 EQUB &01 \ Sub-section 45 = 1 EQUB &03 \ Sub-section 46 = 3 EQUB &00 \ Sub-section 47 = 0 EQUB &FE \ Sub-section 48 = -2 EQUB &00 \ Sub-section 49 = 0 EQUB &01 \ Sub-section 50 = 1 EQUB &FC \ Sub-section 51 = -4 EQUB &FC \ Sub-section 52 = -4 EQUB &03 \ Sub-section 53 = 3 EQUB &03 \ Sub-section 54 = 3 EQUB &FC \ Sub-section 55 = -4 EQUB &FE \ Sub-section 56 = -2 EQUB &01 \ Sub-section 57 = 1Name: trackSlopeDelta [Show more] Type: Variable Category: Extra tracks Summary: The change in the slope (i.e. the change in the gradient) over the course of each segment for each sub-section of the trackContext: See this variable on its own page References: This variable is used as follows: * SetSegmentVector uses trackSlopeDelta.yTrackSignVector EQUB 26 \ Sign 0 = (-16 << 6, 26 << 4, -46 << 6) + section 0 EQUB 76 \ Sign 1 = (-42 << 6, 76 << 4, 4 << 6) + section 2 EQUB -39 \ Sign 2 = (-40 << 6, -39 << 4, 28 << 6) + section 3 EQUB -26 \ Sign 3 = ( 12 << 6, -26 << 4, -20 << 6) + section 5 EQUB 13 \ Sign 4 = ( 9 << 6, 13 << 4, 10 << 6) + section 7 EQUB 8 \ Sign 5 = ( -2 << 6, 8 << 4, -21 << 6) + section 9 EQUB -20 \ Sign 6 = (-10 << 6, -20 << 4, -9 << 6) + section 12 EQUB 6 \ Sign 7 = ( 50 << 6, 6 << 4, 45 << 6) + section 14 EQUB -32 \ Sign 8 = ( 28 << 6, -32 << 4, 27 << 6) + section 14 EQUB 16 \ Sign 9 = (-33 << 6, 16 << 4, 43 << 6) + section 14 EQUB 18 \ Sign 10 = (-12 << 6, 18 << 4, -8 << 6) + section 18 EQUB 5 \ Sign 11 = (-14 << 6, 5 << 4, 16 << 6) + section 19 EQUB 30 \ Sign 12 = ( -8 << 6, 30 << 4, -14 << 6) + section 20 EQUB 1 \ Sign 13 = ( 51 << 6, 1 << 4, 41 << 6) + section 21 EQUB -6 \ Sign 14 = ( 13 << 6, -6 << 4, -20 << 6) + section 22 EQUB 8 \ Sign 15 = ( -4 << 6, 8 << 4, 0 << 6) + section 23Name: yTrackSignVector [Show more] Type: Variable Category: Extra tracks Summary: The y-coordinate of the track sign vector for each sign, to be scaled and added to the inner track section vector for the signContext: See this variable on its own page References: This variable is used as follows: * newContentHi uses yTrackSignVector * newContentLo uses yTrackSignVector.HookSectionFrom STY yStore \ Store the section number in yStore, so we can retrieve \ it at the end of the hook routine LDA trackSectionFrom,Y \ Set thisVectorNumber = the Y-th trackSectionFrom, just STA thisVectorNumber \ like the code that we overwrote with the call to the \ hook routine TYA \ Set Y = Y / 8 LSR A \ LSR A \ So Y now contains the number of the track section (as LSR A \ trackSectionFrom contains the track section * 8) TAY LDA trackYawAngleLo,Y \ Set (yawAngleHi yawAngleLo) to this section's entry STA yawAngleLo \ from (trackYawAngleHi trackYawAngleLo) LDA trackYawAngleHi,Y STA yawAngleHi LDA trackSlope,Y \ Set segmentSlope to this section's entry from STA segmentSlope \ trackSlope LDA trackSubConfig,Y \ Set A to this section's configuration byte LSR A \ Set A = A >> 2, with bit 6 cleared, bit 7 set to the ROR A \ bit 0 of the trackSubConfig entry, and the C flag set \ to bit 1 of the trackSubConfig entry STA subSection \ Store A in subSection, so it contains the index \ from bits 2-7 of trackSubConfig, and bit 7 is set if \ bit 0 of trackSubConfig is set LDA #14 \ Set A = 7, with bit 7 set to the C flag (so if this ROR A \ section's trackSubConfig has bit 1 set, then A is 135, \ otherwise it is 7) STA &23B3 \ Modify the GetSectionAngles routine, at instruction \ #4 after gsec11, to test prevHorizonIndex against the \ value we just calculated in A rather than 7 \ \ So if this section's trackSubConfig has bit 1 set, the \ test becomes prevHorizonIndex <= 135, which is always \ true, so this modification makes us never set the \ horizon line to 7 for sections that have bit 1 of \ trackSubConfig set LDA #0 \ Set subSectionSegment = 0, so we start counting from STA subSectionSegment \ the first segment in the sub-section BIT directionFacing \ If we are facing backwards along the track, jump to BMI from1 \ from1 to skip the following call to SetSegmentVector JSR SetSegmentVector \ We are facing forwards along the track, so calculate \ and store the current segment vector .from1 LDY yStore \ Retrieve the section number from yStore LDA thisVectorNumber \ Set A to the Y-th trackSectionFrom that we set above, \ so the routine sets A to the segment vector number, \ just like the code that we overwrote with the call to \ the hook routine RTS \ Return from the subroutineName: HookSectionFrom [Show more] Type: Subroutine Category: Extra tracks Summary: Initialise and calculate the current segment vector Deep dive: Secrets of the extra tracks Dynamic track generation in the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookSectionFrom * newContentLo calls HookSectionFrom
This routine is called from GetSectionCoords when fetching the coordinates for a track section. It initialises the segment vector calculation process by doing the following: * Fetch the section's yaw angle from the trackYawAngle tables * Fetch the section's slope from the trackSlope table * Initialise the sub-section and sub-section segment variables * Modify the GetSectionAngles routine so the horizon level check is skipped if the section's trackSubConfig has bit 1 set * If we are facing forwards along the track, calculate and store the current segment vector
Arguments: Y The number of the track section * 8 whose coordinates we want to fetch.HookUpdateHorizon PHA \ Store A on the stack so we can retrieve it below LDA segmentCounter \ Set the C flag if segmentCounter >= 12 CMP #12 PLA \ Retrieve the value of A from the stack BCS upho1 \ If segmentCounter >= 12, jump to upho1 to skip the \ following two instructions \ Otherwise we set the horizon line and index using the \ same code that we overwrote with the call to the hook \ routine STA horizonLine \ This track segment is higher than the current horizon \ pitch angle, so the track obscures the horizon and we \ need to update horizonLine to this new pitch angle STY horizonListIndex \ Set horizonListIndex to the track segment number in Y .upho1 RTS \ Return from the subroutineName: HookUpdateHorizon [Show more] Type: Subroutine Category: Extra tracks Summary: Only update the horizon if we have found fewer than 12 visible segments Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookUpdateHorizon * newContentLo calls HookUpdateHorizon
This routine is called from GetVergeAndMarkers so that we only store horizonLine and horizonListIndex when segmentCounter < 12..HookFieldOfView BCC fovw1 \ If A < 20, then this segment is within the 20-degree \ field of view, jump to gseg13 via fovw1 LDA segmentCounter \ If segmentCounter < 10, jump to gseg13 via fovw1 CMP #10 BCC fovw1 RTS \ Return from the subroutine .fovw1 JMP gseg13 \ Jump to gseg13Name: HookFieldOfView [Show more] Type: Subroutine Category: Extra tracks Summary: When populating the verge buffer in GetSegmentAngles, don't give up so easily when we get segments outside the field of view Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookFieldOfView * newContentLo calls HookFieldOfView
This routine is called from GetSegmentAngles to change the logic in at label gseg12, which is applied when a segment is outside the field of view. Note that in the following, the previous segment is further away than the current one. In the original code: * If previous segment's yaw angle >= 20 then the previous segment was also outside the field of view, so return from the subroutine. * Otherwise go to gseg4 to try reducing the size of the segment before returning. In the new code: * If previous segment's yaw angle >= 20 and segmentCounter >= 10, then the previous segment was also outside the field of view AND we have already marked at least 10 segments as being visible, so return from the subroutine. * Otherwise go to gseg13 to mark this segment as visible and keep checking segments. So in the modified version, we keep checking segments until we have reached at least 10.
Arguments: A Yaw angle for the previous segment's right verge C flag Set according to CMP #20.HookFlattenHills TYA \ Set bit 5 of blockOffset to bit 5 of Y, so blockOffset AND #%00100000 \ is non-zero if Y >= 32 (i.e. Y is pointing to the STA blockOffset \ verge buffer for the outer verge edges) LDA #0 \ Set A = 0, so the track line starts at the bottom of \ the screen \ We now work our way backwards through the verge buffer \ from index Y - 1, starting with the closest segments, \ checking the pitch angles and maintaining a maximum \ value in topTrackLine .hill1 STA topTrackLine \ Set topTrackLine = A .hill2 DEY \ Decrement Y to point to the next entry in the verge \ buffer, so we are moving away from the player LDA yVergeRight,Y \ Set A to the pitch angle of the current entry in the \ verge buffer CMP horizonLine \ If A >= horizonLine, then the verge is on or higher BCS hill3 \ than the horizon line, so jump to hill3 to exit the \ hook routine and rejoin the original game code, as \ everything beyond this segment in the verge buffer \ will be hidden CMP topTrackLine \ If A >= topTrackLine, jump back to hill1 to set BCS hill1 \ topTrackLine to A and move on to the next segment, \ so topTrackLine maintains the maximum track line as \ we work through the verge buffer \ If we get here then A < horizonLine (so the verge is \ below the horizon) and A < topTrackLine (so the verge \ is lower than the highest segment already processed) \ \ In other words, this segment is lower than the ones \ before it, so it is hidden by a hill LDA topTrackLine \ Set the pitch angle of entry Y to topTrackLine (this ADC #0 \ ADC instruction has no effect, as we know the C flag STA yVergeRight,Y \ is clear, so I'm not sure what it's doing here - a \ bit of debug code, perhaps?) LDA blockOffset \ If blockOffset is non-zero, loop back to hill2 to move BNE hill2 \ on to the next segment \ If we get here then blockOffset = 0, which will only \ be the case if we are working through the inner verge \ edges (rather than the outer edges), and we haven't \ done the following already \ \ In other words, the following is only done once, for \ the closest segment whose pitch angle dips below the \ segment in front of it (i.e. the closest crest of a \ hill) LDA topTrackLine \ Modify the DrawObject routine at dobj3 instruction #6 STA &1FEA \ so that objects get cut off at track line number \ topTrackLine instead of horizonLine when they are \ hidden behind a hill INY \ Increment Y so the call to gtrm2+6 calculates the \ track width for the previous (i.e. closer) segment in \ the verge buffer JSR gtrm2+6 \ Call the following routine, which has already been \ modified by this point to calculate the following for \ track segment Y (i.e. the segment in front of the \ current one): \ \ horizonTrackWidth \ = 0.8 * |xVergeRightHi - xVergeLeftHi| \ \ So this sets horizonTrackWidth to 80% of the track \ width of the crest of the hill DEY \ Decrement Y back to the correct value for the current \ entry in the verge buffer SEC \ Rotate a 1 into bit 7 of blockOffset so it is now ROR blockOffset \ non-zero, so we only set horizonTrackWidth once as we \ work through the verge buffer BMI hill2 \ Jump back to hill2 (this BMI is effectively a JMP as \ we just set bit 7 of blockOffset) .hill3 LDY vergeBufferEnd \ Set the values of Y and U so they are the same as they DEY \ would be at this point in the original code, without STY U \ the above code being run JMP CheckVergeOnScreen \ Implement the call that we overwrote with the call to \ the hook routine, so we have effectively inserted the \ above code into the main game (the JMP ensures we \ return from the subroutine using a tail call) EQUB &00 \ This byte appears to be unusedName: HookFlattenHills [Show more] Type: Subroutine Category: Extra tracks Summary: Flatten any hills in the verge buffer, calculate the hill height and track width, cut objects off at the hill height Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookFlattenHills * newContentLo calls HookFlattenHills
This routine is called from MapSegmentsToLines to flatten the height of the verge entries in the verge buffer that are hidden by the nearest hill to the player, so that the ground behind the nearest hill is effectively levelled off. It also sets horizonTrackWidth to 80% of the track width at the hill crest.
Arguments: Y Index of the last entry in the track verge buffer - 1: * segmentListRight - 1 for the right verge * segmentListPointer - 1 for the left verge.ModifyGameCode LDX #18 \ We are about to modify 19 two-byte addresses in the \ main game code, so set a counter in X .mods1 LDA modifyAddressHi,X \ Set (U T) = the X-th entry in the (modifyAddressHi STA U \ modifyAddressLo) table, which contains the location LDA modifyAddressLo,X \ of the code to modify in the main game code STA T LDY #0 \ We now modify two bytes, so set an index in Y LDA newContentLo,X \ We want to modify the two-byte address at location \ (U T), setting it to the new address in the \ (newContentHi newContentLo) table, so set A to the \ low byte of the X-th entry from the table, i.e. to \ the low byte of the new address STA (T),Y \ Modify the byte at (U T) to the low byte of the new \ address in A INY \ Increment Y to point to the next byte LDA newContentHi,X \ Set A to the high byte of the X-th entry from the \ table, i.e. to the high byte of the new address STA (T),Y \ Modify the byte at (U T) + 1 to the high byte of the \ new address in A DEX \ Decrement the loop counter to move on to the next \ address to modify BPL mods1 \ Loop back until we have modified all 19 addresses LDA #&4C \ ?&261A = &4C (opcode for a JMP &xxxx instruction) STA &261A STA &248B \ ?&248B = &4C (opcode for a JMP &xxxx instruction) JMP mods2 \ Jump to part 2 EQUB &00 \ This byte pads the routine out to exactly 40 bytesName: ModifyGameCode (Part 1 of 3) [Show more] Type: Subroutine Category: Extra tracks Summary: Modify the game code to support the extra track dataContext: See this subroutine on its own page References: This subroutine is called as follows: * CallTrackHook calls ModifyGameCode
The code modifications are done in three parts. The (modifyAddressHi modifyAddressLo) table contains the locations in the main game code that we want to modify. The (newContentHi newContentLo) table contains the new two-byte addresses that we want to poke into the main game code at the modify locations. This part also does a couple of single-byte modifications. This is also where the xTrackSegmentO table is built, once the modifications have been done. The routine is padded out to be exactly 40 bytes long, so there's one byte for each inner segment x-coordinate..trackSubSize EQUB 26 \ Sub-section 0 EQUB 21 \ Sub-section 1 EQUB 11 \ Sub-section 2 EQUB 10 \ Sub-section 3 EQUB 4 \ Sub-section 4 EQUB 15 \ Sub-section 5 EQUB 21 \ Sub-section 6 EQUB 2 \ Sub-section 7 EQUB 12 \ Sub-section 8 EQUB 12 \ Sub-section 9 EQUB 2 \ Sub-section 10 EQUB 20 \ Sub-section 11 EQUB 27 \ Sub-section 12 EQUB 7 \ Sub-section 13 EQUB 12 \ Sub-section 14 EQUB 3 \ Sub-section 15 EQUB 10 \ Sub-section 16 EQUB 10 \ Sub-section 17 EQUB 29 \ Sub-section 18 EQUB 7 \ Sub-section 19 EQUB 3 \ Sub-section 20 EQUB 11 \ Sub-section 21 EQUB 14 \ Sub-section 22 EQUB 6 \ Sub-section 23 EQUB 21 \ Sub-section 24 EQUB 11 \ Sub-section 25 EQUB 13 \ Sub-section 26 EQUB 6 \ Sub-section 27 EQUB 46 \ Sub-section 28 EQUB 16 \ Sub-section 29 EQUB 16 \ Sub-section 30 EQUB 12 \ Sub-section 31 EQUB 12 \ Sub-section 32 EQUB 8 \ Sub-section 33 EQUB 12 \ Sub-section 34 EQUB 16 \ Sub-section 35 EQUB 4 \ Sub-section 36 EQUB 10 \ Sub-section 37 EQUB 8 \ Sub-section 38 EQUB 5 \ Sub-section 39 EQUB 12 \ Sub-section 40 EQUB 26 \ Sub-section 41 EQUB 8 \ Sub-section 42 EQUB 5 \ Sub-section 43 EQUB 5 \ Sub-section 44 EQUB 5 \ Sub-section 45 EQUB 12 \ Sub-section 46 EQUB 15 \ Sub-section 47 EQUB 21 \ Sub-section 48 EQUB 35 \ Sub-section 49 EQUB 22 \ Sub-section 50 EQUB 3 \ Sub-section 51 EQUB 14 \ Sub-section 52 EQUB 8 \ Sub-section 53 EQUB 19 \ Sub-section 54 EQUB 8 \ Sub-section 55 EQUB 17 \ Sub-section 56 EQUB 34 \ Sub-section 57Name: trackSubSize [Show more] Type: Variable Category: Extra tracks Summary: The size of each sub-section, i.e. the number of segments in each sub-sectionContext: See this variable on its own page References: This variable is used as follows: * UpdateDataPointers uses trackSubSize.zTrackSignVector EQUB -46 \ Sign 0 = (-16 << 6, 26 << 4, -46 << 6) + section 0 EQUB 4 \ Sign 1 = (-42 << 6, 76 << 4, 4 << 6) + section 2 EQUB 28 \ Sign 2 = (-40 << 6, -39 << 4, 28 << 6) + section 3 EQUB -20 \ Sign 3 = ( 12 << 6, -26 << 4, -20 << 6) + section 5 EQUB 10 \ Sign 4 = ( 9 << 6, 13 << 4, 10 << 6) + section 7 EQUB -21 \ Sign 5 = ( -2 << 6, 8 << 4, -21 << 6) + section 9 EQUB -9 \ Sign 6 = (-10 << 6, -20 << 4, -9 << 6) + section 12 EQUB 45 \ Sign 7 = ( 50 << 6, 6 << 4, 45 << 6) + section 14 EQUB 27 \ Sign 8 = ( 28 << 6, -32 << 4, 27 << 6) + section 14 EQUB 43 \ Sign 9 = (-33 << 6, 16 << 4, 43 << 6) + section 14 EQUB -8 \ Sign 10 = (-12 << 6, 18 << 4, -8 << 6) + section 18 EQUB 16 \ Sign 11 = (-14 << 6, 5 << 4, 16 << 6) + section 19 EQUB -14 \ Sign 12 = ( -8 << 6, 30 << 4, -14 << 6) + section 20 EQUB 41 \ Sign 13 = ( 51 << 6, 1 << 4, 41 << 6) + section 21 EQUB -20 \ Sign 14 = ( 13 << 6, -6 << 4, -20 << 6) + section 22 EQUB 0 \ Sign 15 = ( -4 << 6, 8 << 4, 0 << 6) + section 23Name: zTrackSignVector [Show more] Type: Variable Category: Extra tracks Summary: The z-coordinate of the track sign vector for each sign, to be scaled and added to the inner track section vector for the signContext: See this variable on its own page References: This variable is used as follows: * newContentHi uses zTrackSignVector * newContentLo uses zTrackSignVector.HookFixHorizon STA &1FEA \ Modify the DrawObject routine at dobj3 instruction #6 \ so that objects get cut off at the track line number \ in A instead of horizonLine when they are hidden \ behind a hill STA yVergeLeft,Y \ Set the pitch angle for the left side of the horizon \ line in the track verge buffer to the updated value of \ horizonLine (this is the instruction that we overwrote \ with the call to the hook routine, so this makes sure \ we still do this) \ We now work through the verge buffer from index Y up \ to index 8, and do the following for each entry: \ \ * If xVergeRight < xVergeLeft, set \ xVergeRight = xVergeLeft \ \ * Set yVergeRight = yVergeLeft \ \ This appears to squeeze the left verge of the track \ into the right verge, but only for a few entries just \ in front of the horizon section, i.e. for the track \ section list and the first three entries in the track \ segment list .coll1 LDA xVergeRightLo,Y \ Set A = xVergeRight - xVergeLeft for the horizon SEC \ SBC xVergeLeftLo,Y \ starting with the low bytes LDA xVergeRightHi,Y \ And then the high bytes SBC xVergeLeftHi,Y BPL coll2 \ If the result is positive, jump to coll2 to skip the \ following \ If we get here then the result is negative, so \ xVergeRight < xVergeLeft LDA xVergeRightLo,Y \ Set xVergeRight = xVergeLeft STA xVergeLeftLo,Y LDA xVergeRightHi,Y STA xVergeLeftHi,Y .coll2 LDA yVergeRight,Y \ Set yVergeRight = yVergeLeft STA yVergeLeft,Y INY \ Increment the verge buffer index CPY #9 \ Loop back until we have processed up to index 8 BCC coll1 LDY horizonListIndex \ Restore the value of Y that we had on entering the \ hook routine RTS \ Return from the subroutineName: HookFixHorizon [Show more] Type: Subroutine Category: Extra tracks Summary: Apply the horizon line in A instead of horizonLine Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookFixHorizon * newContentLo calls HookFixHorizon
This routine is called from GetTrackAndMarkers. It does the following: * Cut objects off at the track line in A rather than horizonLine * Collapse the left verge of the track into the right verge, but only for a few entries just in front of the horizon section, i.e. for the track section list and the first three entries in the track segment list
Arguments: A The updated value of horizonLine Y The horizon section index in the verge buffer from horizonListIndex.HookJoystick LDY currentPlayer \ Set A to the track section number * 8 for the current LDA objTrackSection,Y \ player LDY #181 \ Set Y = 181 so we scale the steering by 1.00 CMP #32 \ If the track section <> 32 (i.e. section 4), jump to BNE joys1 \ joys1 to skip the following instruction LDY #240 \ The player is in track section 4, so set Y = 240 to \ scale the steering by 1.76 .joys1 TYA \ Set A = Y \ \ So A is 240 if this is track section 4, or 181 for all \ other sections JSR Multiply8x8 \ Set (A T) = A * U \ = A * x-axis STA U \ Set U = A \ = high byte of A * x-axis JSR Multiply8x8 \ Set (A T) = A * U \ = A * A \ = (A * x-axis) ^ 2 ASL T \ Set (A T) = (A T) * 2 ROL A \ = 2 * (A * x-axis) ^ 2 \ So for A = 240 (track section 4) we have: \ \ (A T) = 2 * (240/256 * x-axis) ^ 2 \ = 2 * (0.938 * x-axis) ^ 2 \ = 1.76 * x-axis ^ 2 \ \ and for A = 181 (all other sections) we have: \ \ (A T) = 2 * (181/256 * x-axis) ^ 2 \ = 2 * (0.707 * x-axis) ^ 2 \ = 1.00 * x-axis ^ 2 RTS \ Return from the subroutineName: HookJoystick [Show more] Type: Subroutine Category: Extra tracks Summary: Apply enhanced joystick steering to specific track sections Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookJoystick * newContentLo calls HookJoystick
This routine is called from ProcessDrivingKeys to make it easier to steer round the Druids hairpin bend when using a joystick. If this is track section 4, set: (A T) = 1.76 * x-axis ^ 2 otherwise set: (A T) = x-axis ^ 2 The latter is the same as the existing game code, so this hook only affects track section 4.
Arguments: U The joystick x-axis high byte.Multiply8x8Signed PHP \ Store the N flag on the stack, as set by the LDA just \ before the call, so this equals abs(A) JMP MultiplyHeight+11 \ Jump into the MultiplyHeight routine to do this: \ \ JSR Absolute8Bit \ Set A = |A| \ \ JSR Multiply8x8 \ Set (A T) = A * U \ \ = |A| * U \ \ \ \ So A = |A| * U / 256 \ \ PLP \ Retrieve sign in N, which we \ \ set to abs(A) above \ \ JSR Absolute8Bit \ Set A = |A| * abs(A) \ \ = A * U / 256 \ \ RTS \ Return from the subroutine \ \ So this sets A = A * U while retaining the sign in AName: Multiply8x8Signed [Show more] Type: Subroutine Category: Extra tracks Summary: Multiply two 8-bit numbers, one of which is signedContext: See this subroutine on its own page References: This subroutine is called as follows: * CalcSegmentVector calls Multiply8x8Signed
This routine calculates the following, retaining the sign in A. A = A * U / 256 Specifically, if the last instruction to affect the N flag before the call is an LDA instruction, and A is signed, then set: A = |A| * U * abs(A) = A * U / 256 So this multiplies A and U, retaining the sign in A..xTrackCurve EQUB 0 \ Coordinate 0 = (0, 120) EQUB 1 \ Coordinate 1 = (1, 120) EQUB 3 \ Coordinate 2 = (3, 120) EQUB 4 \ Coordinate 3 = (4, 120) EQUB 6 \ Coordinate 4 = (6, 120) EQUB 7 \ Coordinate 5 = (7, 120) EQUB 9 \ Coordinate 6 = (9, 120) EQUB 10 \ Coordinate 7 = (10, 120) EQUB 12 \ Coordinate 8 = (12, 119) EQUB 13 \ Coordinate 9 = (13, 119) EQUB 15 \ Coordinate 10 = (15, 119) EQUB 16 \ Coordinate 11 = (16, 119) EQUB 18 \ Coordinate 12 = (18, 119) EQUB 19 \ Coordinate 13 = (19, 118) EQUB 21 \ Coordinate 14 = (21, 118) EQUB 22 \ Coordinate 15 = (22, 118) EQUB 23 \ Coordinate 16 = (23, 118) EQUB 25 \ Coordinate 17 = (25, 117) EQUB 26 \ Coordinate 18 = (26, 117) EQUB 28 \ Coordinate 19 = (28, 117) EQUB 29 \ Coordinate 20 = (29, 116) EQUB 31 \ Coordinate 21 = (31, 116) EQUB 32 \ Coordinate 22 = (32, 116) EQUB 33 \ Coordinate 23 = (33, 115) EQUB 35 \ Coordinate 24 = (35, 115) EQUB 36 \ Coordinate 25 = (36, 114) EQUB 38 \ Coordinate 26 = (38, 114) EQUB 39 \ Coordinate 27 = (39, 113) EQUB 40 \ Coordinate 28 = (40, 113) EQUB 42 \ Coordinate 29 = (42, 112) EQUB 43 \ Coordinate 30 = (43, 112) EQUB 45 \ Coordinate 31 = (45, 111) EQUB 46 \ Coordinate 32 = (46, 111) EQUB 47 \ Coordinate 33 = (47, 110) EQUB 49 \ Coordinate 34 = (49, 110) EQUB 50 \ Coordinate 35 = (50, 109) EQUB 51 \ Coordinate 36 = (51, 108) EQUB 53 \ Coordinate 37 = (53, 108) EQUB 54 \ Coordinate 38 = (54, 107) EQUB 55 \ Coordinate 39 = (55, 107) EQUB 57 \ Coordinate 40 = (57, 106) EQUB 58 \ Coordinate 41 = (58, 105) EQUB 59 \ Coordinate 42 = (59, 104) EQUB 60 \ Coordinate 43 = (60, 104) EQUB 62 \ Coordinate 44 = (62, 103) EQUB 63 \ Coordinate 45 = (63, 102) EQUB 64 \ Coordinate 46 = (64, 101) EQUB 65 \ Coordinate 47 = (65, 101) EQUB 67 \ Coordinate 48 = (67, 100) EQUB 68 \ Coordinate 49 = (68, 99) EQUB 69 \ Coordinate 50 = (69, 98) EQUB 70 \ Coordinate 51 = (70, 97) EQUB 71 \ Coordinate 52 = (71, 96) EQUB 73 \ Coordinate 53 = (73, 96) EQUB 74 \ Coordinate 54 = (74, 95) EQUB 75 \ Coordinate 55 = (75, 94) EQUB 76 \ Coordinate 56 = (76, 93) EQUB 77 \ Coordinate 57 = (77, 92) EQUB 78 \ Coordinate 58 = (78, 91) EQUB 79 \ Coordinate 59 = (79, 90) EQUB 81 \ Coordinate 60 = (81, 89) EQUB 82 \ Coordinate 61 = (82, 88) EQUB 83 \ Coordinate 62 = (83, 87) EQUB 84 \ Coordinate 63 = (84, 86) EQUB 85 \ Coordinate 64 = (85, 85)Name: xTrackCurve [Show more] Type: Variable Category: Extra tracks Summary: The x-coordinate of the tangent vector (i.e. the curve direction) at 64 points on a one-eighth circle covering 0 to 45 degreesContext: See this variable on its own page References: This variable is used as follows: * CalcSegmentVector uses xTrackCurve.mods2 LDA #&20 \ ?&1248 = &20 (opcode for a JSR instruction) STA &1248 STA &12FB \ ?&12FB = &20 (opcode for a JSR instruction) STA &2538 \ ?&2538 = &20 (opcode for a JSR instruction) STA &45CB \ ?&45CB = &20 (opcode for a JSR instruction) LDA #&EA \ ?&2545 = &EA (opcode for a NOP instruction) STA &2545 LDA #22 \ ?&4F55 = 22 (argument in a CMP #22 instruction) STA &4F55 STA &4F59 \ ?&4F59 = 22 (argument in a CMP #22 instruction) LDA #13 \ ?&24EA = 13 (argument in a CMP #13 instruction) STA &24EA LDA #&A2 \ ?&1FE9 = &A2 (opcode for a LDX # instruction) STA &1FE9 JMP mods3 \ Jump to part 3Name: ModifyGameCode (Part 2 of 3) [Show more] Type: Subroutine Category: Extra tracks Summary: Modify the game code to support the extra track dataContext: See this subroutine on its own page References: No direct references to this subroutine in this source file
The code modifications are done in three parts. This is also where the zTrackSegmentO table is built, once the modifications have been done. The routine is exactly 40 bytes long, so there's one byte for each outer segment z-coordinate..trackSlope EQUB &FF \ Section 0 = -1 EQUB &E4 \ Section 1 = -28 EQUB &CC \ Section 2 = -52 EQUB &32 \ Section 3 = 50 EQUB &DE \ Section 4 = -34 EQUB &D0 \ Section 5 = -48 EQUB &D0 \ Section 6 = -48 EQUB &00 \ Section 7 = 0 EQUB &00 \ Section 8 = 0 EQUB &00 \ Section 9 = 0 EQUB &00 \ Section 10 = 0 EQUB &41 \ Section 11 = 65 EQUB &FF \ Section 12 = -1 EQUB &FF \ Section 13 = -1 EQUB &FF \ Section 14 = -1 EQUB &3B \ Section 15 = 59 EQUB &FB \ Section 16 = -5 EQUB &FB \ Section 17 = -5 EQUB &FF \ Section 18 = -1 EQUB &03 \ Section 19 = 3 EQUB &1B \ Section 20 = 27 EQUB &1B \ Section 21 = 27 EQUB &FD \ Section 22 = -3 EQUB &FD \ Section 23 = -3 EQUB &26 \ Section 24 = 38 EQUB &FC \ Section 25 = -4 EQUB &12 \ Section 26 = 18 EQUB &E6 \ Section 27 = -26 EQUB &FF \ Section 28 = -1 EQUB &00 \ This byte appears to be unusedName: trackSlope [Show more] Type: Variable Category: Extra tracks Summary: The slope at the start of each track sectionContext: See this variable on its own page References: This variable is used as follows: * HookSectionFrom uses trackSlope.trackYawAngleLo EQUB &00 \ Section 0 = &0000 = 0 = 0.0 degrees EQUB &2F \ Section 1 = &122F = 4655 = 25.6 degrees EQUB &8A \ Section 2 = &508A = 20618 = 113.3 degrees EQUB &E0 \ Section 3 = &55E0 = 21984 = 120.8 degrees EQUB &E0 \ Section 4 = &55E0 = 21984 = 120.8 degrees EQUB &A4 \ Section 5 = &D2A4 = 53924 = 296.2 degrees EQUB &A4 \ Section 6 = &D2A4 = 53924 = 296.2 degrees EQUB &52 \ Section 7 = &9D52 = 40274 = 221.2 degrees EQUB &52 \ Section 8 = &9D52 = 40274 = 221.2 degrees EQUB &47 \ Section 9 = &8747 = 34631 = 190.2 degrees EQUB &42 \ Section 10 = &7642 = 30274 = 166.3 degrees EQUB &0A \ Section 11 = &1D0A = 7434 = 40.8 degrees EQUB &0A \ Section 12 = &1D0A = 7434 = 40.8 degrees EQUB &92 \ Section 13 = &2592 = 9618 = 52.8 degrees EQUB &92 \ Section 14 = &2592 = 9618 = 52.8 degrees EQUB &92 \ Section 15 = &2592 = 9618 = 52.8 degrees EQUB &0A \ Section 16 = &620A = 25098 = 137.9 degrees EQUB &0A \ Section 17 = &620A = 25098 = 137.9 degrees EQUB &0E \ Section 18 = &A20E = 41486 = 227.9 degrees EQUB &0E \ Section 19 = &A20E = 41486 = 227.9 degrees EQUB &9E \ Section 20 = &B59E = 46494 = 255.4 degrees EQUB &9E \ Section 21 = &B59E = 46494 = 255.4 degrees EQUB &6C \ Section 22 = &E26C = 57964 = 318.4 degrees EQUB &6C \ Section 23 = &E26C = 57964 = 318.4 degrees EQUB &B3 \ Section 24 = &A1B3 = 41395 = 227.4 degrees EQUB &B3 \ Section 25 = &A1B3 = 41395 = 227.4 degrees EQUB &B3 \ Section 26 = &A1B3 = 41395 = 227.4 degrees EQUB &28 \ Section 27 = &DF28 = 57128 = 313.8 degrees EQUB &C8 \ Section 28 = &F3C8 = 62408 = 342.8 degrees EQUB &00 \ This byte appears to be unusedName: trackYawAngleLo [Show more] Type: Variable Category: Extra tracks Summary: The low byte of the yaw angle of the start of each track section (i.e. the direction of the track at that point)Context: See this variable on its own page References: This variable is used as follows: * HookSectionFrom uses trackYawAngleLo.trackYawAngleHi EQUB &00 \ Section 0 = &0000 = 0 = 0.0 degrees EQUB &12 \ Section 1 = &122F = 4655 = 25.6 degrees EQUB &50 \ Section 2 = &508A = 20618 = 113.3 degrees EQUB &55 \ Section 3 = &55E0 = 21984 = 120.8 degrees EQUB &55 \ Section 4 = &55E0 = 21984 = 120.8 degrees EQUB &D2 \ Section 5 = &D2A4 = 53924 = 296.2 degrees EQUB &D2 \ Section 6 = &D2A4 = 53924 = 296.2 degrees EQUB &9D \ Section 7 = &9D52 = 40274 = 221.2 degrees EQUB &9D \ Section 8 = &9D52 = 40274 = 221.2 degrees EQUB &87 \ Section 9 = &8747 = 34631 = 190.2 degrees EQUB &76 \ Section 10 = &7642 = 30274 = 166.3 degrees EQUB &1D \ Section 11 = &1D0A = 7434 = 40.8 degrees EQUB &1D \ Section 12 = &1D0A = 7434 = 40.8 degrees EQUB &25 \ Section 13 = &2592 = 9618 = 52.8 degrees EQUB &25 \ Section 14 = &2592 = 9618 = 52.8 degrees EQUB &25 \ Section 15 = &2592 = 9618 = 52.8 degrees EQUB &62 \ Section 16 = &620A = 25098 = 137.9 degrees EQUB &62 \ Section 17 = &620A = 25098 = 137.9 degrees EQUB &A2 \ Section 18 = &A20E = 41486 = 227.9 degrees EQUB &A2 \ Section 19 = &A20E = 41486 = 227.9 degrees EQUB &B5 \ Section 20 = &B59E = 46494 = 255.4 degrees EQUB &B5 \ Section 21 = &B59E = 46494 = 255.4 degrees EQUB &E2 \ Section 22 = &E26C = 57964 = 318.4 degrees EQUB &E2 \ Section 23 = &E26C = 57964 = 318.4 degrees EQUB &A1 \ Section 24 = &A1B3 = 41395 = 227.4 degrees EQUB &A1 \ Section 25 = &A1B3 = 41395 = 227.4 degrees EQUB &A1 \ Section 26 = &A1B3 = 41395 = 227.4 degrees EQUB &DF \ Section 27 = &DF28 = 57128 = 313.8 degrees EQUB &F3 \ Section 28 = &F3C8 = 62408 = 342.8 degrees EQUB &00 \ This byte appears to be unusedName: trackYawAngleHi [Show more] Type: Variable Category: Extra tracks Summary: The high byte of the yaw angle of the start of each track section (i.e. the direction of the track at that point)Context: See this variable on its own page References: This variable is used as follows: * HookSectionFrom uses trackYawAngleHi.trackSubConfig EQUB %00000010 \ Section 0 = 000000 1 0 From 0 no check curve EQUB %00001110 \ Section 1 = 000011 1 0 From 3 no check curve EQUB %00011010 \ Section 2 = 000110 1 0 From 6 no check curve EQUB %00100010 \ Section 3 = 001000 1 0 From 8 no check curve EQUB %00101010 \ Section 4 = 001010 1 0 From 10 no check curve EQUB %00110010 \ Section 5 = 001100 1 0 From 12 no check curve EQUB %00110110 \ Section 6 = 001101 1 0 From 13 no check curve EQUB %00111111 \ Section 7 = 001111 1 1 From 15 no check straight EQUB %00111110 \ Section 8 = 001111 1 0 From 15 no check curve EQUB %01000110 \ Section 9 = 010001 1 0 From 17 no check curve EQUB %01010010 \ Section 10 = 010100 1 0 From 20 no check curve EQUB %01100010 \ Section 11 = 011000 1 0 From 24 no check curve EQUB %01101010 \ Section 12 = 011010 1 0 From 26 no check curve EQUB %01110110 \ Section 13 = 011101 1 0 From 29 no check curve EQUB %01111110 \ Section 14 = 011111 1 0 From 31 no check curve EQUB %10000100 \ Section 15 = 100001 0 0 From 33 check curve EQUB %10010001 \ Section 16 = 100100 0 1 From 36 check straight EQUB %10010010 \ Section 17 = 100100 1 0 From 36 no check curve EQUB %10100010 \ Section 18 = 101000 1 0 From 40 no check curve EQUB %10101010 \ Section 19 = 101010 1 0 From 42 no check curve EQUB %10101111 \ Section 20 = 101011 1 1 From 43 no check straight EQUB %10101110 \ Section 21 = 101011 1 0 From 43 no check curve EQUB %10110101 \ Section 22 = 101101 0 1 From 45 check straight EQUB %10110100 \ Section 23 = 101101 0 0 From 45 check curve EQUB %10111100 \ Section 24 = 101111 0 0 From 47 check curve EQUB %11000100 \ Section 25 = 110001 0 0 From 49 check curve EQUB %11001110 \ Section 26 = 110011 1 0 From 51 no check curve EQUB %11011010 \ Section 27 = 110110 1 0 From 54 no check curve EQUB %11100010 \ Section 28 = 111000 1 0 From 56 no check curve EQUB &00 \ This byte appears to be unusedName: trackSubConfig [Show more] Type: Variable Category: Extra tracks Summary: Configuration data for each section that defines the sub-section numbers, and horizon calculationsContext: See this variable on its own page References: This variable is used as follows: * HookSectionFrom uses trackSubConfig
Each section has a trackSubConfig value that contains the following data: * Bits 2 to 7 = the number of the first sub-section in this section * Bit 1 = if this is set, then in the horizon calculations, we skip the check that sets horizonLine to 7 * Bit 0 = if this is set, then the segment vectors for this section are generated as a straight track rather than using the curve tables (this bit is only set for straight sections) In the last one, if bit 0 is set then bit 7 of subSection gets set. This makes us skip the first part of the SetSegmentVector routine, which means we do not update the yaw angle or track height before calculating the segment vector. This means we reuse the segment vector from the end of the previous section for generating this track section. This is only done for straight sections, and the main game code draws straight sections by simply adding the same track segment vector for each segment in the straight, so setting bit 0 of a section's trackSubConfig ensures that it heads off in a straight line in the exact same direction as the tail end of the preceding section..trackSteering EQUB %00011000 \ Section 0 = 000110 0 0 <- 6* EQUB %00110011 \ Section 1 = 001100 1 1 -> 12 EQUB %00011000 \ Section 2 = 000110 0 0 <- 6* EQUB %00000000 \ Section 3 = 000000 0 0 <- 0* EQUB %01001111 \ Section 4 = 010011 1 1 -> 19 EQUB %00110001 \ Section 5 = 001100 0 1 -> 12* EQUB %01101000 \ Section 6 = 011010 0 0 <- 26* EQUB %00011001 \ Section 7 = 000110 0 1 -> 6* EQUB %00110000 \ Section 8 = 001100 0 0 <- 12* EQUB %00011001 \ Section 9 = 000110 0 1 -> 6* EQUB %00101110 \ Section 10 = 001011 1 0 <- 11 EQUB %00011000 \ Section 11 = 000110 0 0 <- 6* EQUB %00011000 \ Section 12 = 000110 0 0 <- 6* EQUB %00011000 \ Section 13 = 000110 0 0 <- 6* EQUB %00011000 \ Section 14 = 000110 0 0 <- 6* EQUB %00110011 \ Section 15 = 001100 1 1 -> 12 EQUB %00011000 \ Section 16 = 000110 0 0 <- 6* EQUB %00111111 \ Section 17 = 001111 1 1 -> 15 EQUB %00011000 \ Section 18 = 000110 0 0 <- 6* EQUB %01010101 \ Section 19 = 010101 0 1 -> 21* EQUB %00011000 \ Section 20 = 000110 0 0 <- 6* EQUB %01011011 \ Section 21 = 010110 1 1 -> 22 EQUB %00110101 \ Section 22 = 001101 0 1 -> 13* EQUB %01000010 \ Section 23 = 010000 1 0 <- 16 EQUB %00011000 \ Section 24 = 000110 0 0 <- 6* EQUB %00011000 \ Section 25 = 000110 0 0 <- 6* EQUB %01001011 \ Section 26 = 010010 1 1 -> 18 EQUB %00011000 \ Section 27 = 000110 0 0 <- 6* EQUB %00011000 \ Section 28 = 000110 0 0 <- 6* EQUB &18, &00 \ These bytes appear to be unusedName: trackSteering [Show more] Type: Variable Category: Extra tracks Summary: The optimum steering for non-player drivers on each track section Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: This variable is used as follows: * newContentHi uses trackSteering * newContentLo uses trackSteering
The following bytes are copied to sectionSteering by the GetSectionSteering routine, and are processed on the way. * Bit 0 becomes bit 7 of the result, to determine the direction of steering (shown with a directional arrow below) * Bit 1 clear means the result is multiplied by baseSpeed, so steering on straight sections is proportional to the track speed (this is shown with an asterisk * below) * Bits 2 to 7 contain the amount of steering to apply The processed values are shown below..zTrackCurve EQUB 120 \ Coordinate 0 = (0, 120) EQUB 120 \ Coordinate 1 = (1, 120) EQUB 120 \ Coordinate 2 = (3, 120) EQUB 120 \ Coordinate 3 = (4, 120) EQUB 120 \ Coordinate 4 = (6, 120) EQUB 120 \ Coordinate 5 = (7, 120) EQUB 120 \ Coordinate 6 = (9, 120) EQUB 120 \ Coordinate 7 = (10, 120) EQUB 119 \ Coordinate 8 = (12, 119) EQUB 119 \ Coordinate 9 = (13, 119) EQUB 119 \ Coordinate 10 = (15, 119) EQUB 119 \ Coordinate 11 = (16, 119) EQUB 119 \ Coordinate 12 = (18, 119) EQUB 118 \ Coordinate 13 = (19, 118) EQUB 118 \ Coordinate 14 = (21, 118) EQUB 118 \ Coordinate 15 = (22, 118) EQUB 118 \ Coordinate 16 = (23, 118) EQUB 117 \ Coordinate 17 = (25, 117) EQUB 117 \ Coordinate 18 = (26, 117) EQUB 117 \ Coordinate 19 = (28, 117) EQUB 116 \ Coordinate 20 = (29, 116) EQUB 116 \ Coordinate 21 = (31, 116) EQUB 116 \ Coordinate 22 = (32, 116) EQUB 115 \ Coordinate 23 = (33, 115) EQUB 115 \ Coordinate 24 = (35, 115) EQUB 114 \ Coordinate 25 = (36, 114) EQUB 114 \ Coordinate 26 = (38, 114) EQUB 113 \ Coordinate 27 = (39, 113) EQUB 113 \ Coordinate 28 = (40, 113) EQUB 112 \ Coordinate 29 = (42, 112) EQUB 112 \ Coordinate 30 = (43, 112) EQUB 111 \ Coordinate 31 = (45, 111) EQUB 111 \ Coordinate 32 = (46, 111) EQUB 110 \ Coordinate 33 = (47, 110) EQUB 110 \ Coordinate 34 = (49, 110) EQUB 109 \ Coordinate 35 = (50, 109) EQUB 108 \ Coordinate 36 = (51, 108) EQUB 108 \ Coordinate 37 = (53, 108) EQUB 107 \ Coordinate 38 = (54, 107) EQUB 107 \ Coordinate 39 = (55, 107) EQUB 106 \ Coordinate 40 = (57, 106) EQUB 105 \ Coordinate 41 = (58, 105) EQUB 104 \ Coordinate 42 = (59, 104) EQUB 104 \ Coordinate 43 = (60, 104) EQUB 103 \ Coordinate 44 = (62, 103) EQUB 102 \ Coordinate 45 = (63, 102) EQUB 101 \ Coordinate 46 = (64, 101) EQUB 101 \ Coordinate 47 = (65, 101) EQUB 100 \ Coordinate 48 = (67, 100) EQUB 99 \ Coordinate 49 = (68, 99) EQUB 98 \ Coordinate 50 = (69, 98) EQUB 97 \ Coordinate 51 = (70, 97) EQUB 96 \ Coordinate 52 = (71, 96) EQUB 96 \ Coordinate 53 = (73, 96) EQUB 95 \ Coordinate 54 = (74, 95) EQUB 94 \ Coordinate 55 = (75, 94) EQUB 93 \ Coordinate 56 = (76, 93) EQUB 92 \ Coordinate 57 = (77, 92) EQUB 91 \ Coordinate 58 = (78, 91) EQUB 90 \ Coordinate 59 = (79, 90) EQUB 89 \ Coordinate 60 = (81, 89) EQUB 88 \ Coordinate 61 = (82, 88) EQUB 87 \ Coordinate 62 = (83, 87) EQUB 86 \ Coordinate 63 = (84, 86) EQUB 85 \ Coordinate 64 = (85, 85)Name: zTrackCurve [Show more] Type: Variable Category: Extra tracks Summary: The z-coordinate of the tangent vector (i.e. the curve direction) at 64 points on a one-eighth circle covering 0 to 45 degreesContext: See this variable on its own page References: This variable is used as follows: * CalcSegmentVector uses zTrackCurve\ Track section 0 EQUB %01110000 \ trackSectionFlag Sp=0 G=1 Mc=1 Mlr=10 Vc=00 Sh=0 EQUB &20 \ xTrackSectionILo xTrackSectionI = &D120 = -12000 EQUB &00 \ yTrackSectionILo yTrackSectionI = &1400 = 5120 EQUB &A0 \ zTrackSectionILo zTrackSectionI = &0FA0 = 4000 EQUB &21 \ xTrackSectionOLo xTrackSectionO = &D021 = -12255 EQUB 0 \ trackSectionFrom EQUB &A0 \ zTrackSectionOLo zTrackSectionO = &0FA0 = 4000 EQUB 58 \ trackSectionSize \ Track section 1 EQUB %11101101 \ trackSectionFlag Sp=1 G=1 Mc=1 Mlr=01 Vc=10 Sh=1 EQUB &DC \ xTrackSectionILo xTrackSectionI = &D4DC = -11044 EQUB &87 \ yTrackSectionILo yTrackSectionI = &1487 = 5255 EQUB &5C \ zTrackSectionILo zTrackSectionI = &2A5C = 10844 EQUB &F6 \ xTrackSectionOLo xTrackSectionO = &D3F6 = -11274 EQUB 18 \ trackSectionFrom EQUB &C8 \ zTrackSectionOLo zTrackSectionO = &2AC8 = 10952 EQUB 29 \ trackSectionSize \ Track section 2 EQUB %01000010 \ trackSectionFlag Sp=0 G=1 Mc=0 Mlr=00 Vc=01 Sh=0 EQUB &52 \ xTrackSectionILo xTrackSectionI = &E052 = -8110 EQUB &2B \ yTrackSectionILo yTrackSectionI = &0F2B = 3883 EQUB &E3 \ zTrackSectionILo zTrackSectionI = &2DE3 = 11747 EQUB &B5 \ xTrackSectionOLo xTrackSectionO = &E0B5 = -8011 EQUB 7 \ trackSectionFrom EQUB &CC \ zTrackSectionOLo zTrackSectionO = &2ECC = 11980 EQUB 23 \ trackSectionSize \ Track section 3 EQUB %01110000 \ trackSectionFlag Sp=0 G=1 Mc=1 Mlr=10 Vc=00 Sh=0 EQUB &2B \ xTrackSectionILo xTrackSectionI = &EA2B = -5589 EQUB &DE \ yTrackSectionILo yTrackSectionI = &0EDE = 3806 EQUB &96 \ zTrackSectionILo zTrackSectionI = &2996 = 10646 EQUB &AA \ xTrackSectionOLo xTrackSectionO = &EAAA = -5462 EQUB 30 \ trackSectionFrom EQUB &73 \ zTrackSectionOLo zTrackSectionO = &2A73 = 10867 EQUB 24 \ trackSectionSize \ Track section 4 EQUB %11101101 \ trackSectionFlag Sp=1 G=1 Mc=1 Mlr=01 Vc=10 Sh=1 EQUB &EB \ xTrackSectionILo xTrackSectionI = &F3EB = -3093 EQUB &6C \ yTrackSectionILo yTrackSectionI = &116C = 4460 EQUB &F6 \ zTrackSectionILo zTrackSectionI = &23F6 = 9206 EQUB &6A \ xTrackSectionOLo xTrackSectionO = &F46A = -2966 EQUB 14 \ trackSectionFrom EQUB &D3 \ zTrackSectionOLo zTrackSectionO = &24D3 = 9427 EQUB 22 \ trackSectionSize \ Track section 5 EQUB %01101010 \ trackSectionFlag Sp=0 G=1 Mc=1 Mlr=01 Vc=01 Sh=0 EQUB &71 \ xTrackSectionILo xTrackSectionI = &F171 = -3727 EQUB &53 \ yTrackSectionILo yTrackSectionI = &0D53 = 3411 EQUB &53 \ zTrackSectionILo zTrackSectionI = &1E53 = 7763 EQUB &00 \ xTrackSectionOLo xTrackSectionO = &F100 = -3840 EQUB 36 \ trackSectionFrom EQUB &6D \ zTrackSectionOLo zTrackSectionO = &1D6D = 7533 EQUB 27 \ trackSectionSize \ Track section 6 EQUB %01110011 \ trackSectionFlag Sp=0 G=1 Mc=1 Mlr=10 Vc=01 Sh=1 EQUB &0D \ xTrackSectionILo xTrackSectionI = &E60D = -6643 EQUB &43 \ yTrackSectionILo yTrackSectionI = &0843 = 2115 EQUB &EA \ zTrackSectionILo zTrackSectionI = &23EA = 9194 EQUB &9C \ xTrackSectionOLo xTrackSectionO = &E59C = -6756 EQUB 23 \ trackSectionFrom EQUB &04 \ zTrackSectionOLo zTrackSectionO = &2304 = 8964 EQUB 19 \ trackSectionSize \ Track section 7 EQUB %00000100 \ trackSectionFlag Sp=0 G=0 Mc=0 Mlr=00 Vc=10 Sh=0 EQUB &2F \ xTrackSectionILo xTrackSectionI = &DE2F = -8657 EQUB &EB \ yTrackSectionILo yTrackSectionI = &05EB = 1515 EQUB &20 \ zTrackSectionILo zTrackSectionI = &2120 = 8480 EQUB &F0 \ xTrackSectionOLo xTrackSectionO = &DEF0 = -8464 EQUB 2 \ trackSectionFrom EQUB &7A \ zTrackSectionOLo zTrackSectionO = &207A = 8314 EQUB 13 \ trackSectionSize \ Track section 8 EQUB %01000001 \ trackSectionFlag Sp=0 G=1 Mc=0 Mlr=00 Vc=00 Sh=1 EQUB &39 \ xTrackSectionILo xTrackSectionI = &DA39 = -9671 EQUB &EB \ yTrackSectionILo yTrackSectionI = &05EB = 1515 EQUB &81 \ zTrackSectionILo zTrackSectionI = &1C81 = 7297 EQUB &FA \ xTrackSectionOLo xTrackSectionO = &DAFA = -9478 EQUB 3 \ trackSectionFrom EQUB &DB \ zTrackSectionOLo zTrackSectionO = &1BDB = 7131 EQUB 13 \ trackSectionSize \ Track section 9 EQUB %01101000 \ trackSectionFlag Sp=0 G=1 Mc=1 Mlr=01 Vc=00 Sh=0 EQUB &36 \ xTrackSectionILo xTrackSectionI = &D836 = -10186 EQUB &EB \ yTrackSectionILo yTrackSectionI = &05EB = 1515 EQUB &CE \ zTrackSectionILo zTrackSectionI = &16CE = 5838 EQUB &30 \ xTrackSectionOLo xTrackSectionO = &D930 = -9936 EQUB 16 \ trackSectionFrom EQUB &A1 \ zTrackSectionOLo zTrackSectionO = &16A1 = 5793 EQUB 46 \ trackSectionSize \ Track section 10 EQUB %11110011 \ trackSectionFlag Sp=1 G=1 Mc=1 Mlr=10 Vc=01 Sh=1 EQUB &0A \ xTrackSectionILo xTrackSectionI = &D90A = -9974 EQUB &EB \ yTrackSectionILo yTrackSectionI = &05EB = 1515 EQUB &52 \ zTrackSectionILo zTrackSectionI = &0152 = 338 EQUB &00 \ xTrackSectionOLo xTrackSectionO = &DA00 = -9728 EQUB 22 \ trackSectionFrom EQUB &8F \ zTrackSectionOLo zTrackSectionO = &018F = 399 EQUB 34 \ trackSectionSize \ Track section 11 EQUB %11000100 \ trackSectionFlag Sp=1 G=1 Mc=0 Mlr=00 Vc=10 Sh=0 EQUB &58 \ xTrackSectionILo xTrackSectionI = &E558 = -6824 EQUB &DF \ yTrackSectionILo yTrackSectionI = &0ADF = 2783 EQUB &7C \ zTrackSectionILo zTrackSectionI = &FC7C = -900 EQUB &96 \ xTrackSectionOLo xTrackSectionO = &E496 = -7018 EQUB 16 \ trackSectionFrom EQUB &21 \ zTrackSectionOLo zTrackSectionO = &FD21 = -735 EQUB 32 \ trackSectionSize \ Track section 12 EQUB %01000000 \ trackSectionFlag Sp=0 G=1 Mc=0 Mlr=00 Vc=00 Sh=0 EQUB &18 \ xTrackSectionILo xTrackSectionI = &EF18 = -4328 EQUB &73 \ yTrackSectionILo yTrackSectionI = &1173 = 4467 EQUB &DC \ zTrackSectionILo zTrackSectionI = &07DC = 2012 EQUB &56 \ xTrackSectionOLo xTrackSectionO = &EE56 = -4522 EQUB 8 \ trackSectionFrom EQUB &81 \ zTrackSectionOLo zTrackSectionO = &0881 = 2177 EQUB 65 \ trackSectionSize \ Track section 13 EQUB %01000000 \ trackSectionFlag Sp=0 G=1 Mc=0 Mlr=00 Vc=00 Sh=0 EQUB &61 \ xTrackSectionILo xTrackSectionI = &0661 = 1633 EQUB &32 \ yTrackSectionILo yTrackSectionI = &1132 = 4402 EQUB &7F \ zTrackSectionILo zTrackSectionI = &1B7F = 7039 EQUB &C5 \ xTrackSectionOLo xTrackSectionO = &05C5 = 1477 EQUB 34 \ trackSectionFrom EQUB &4B \ zTrackSectionOLo zTrackSectionO = &1C4B = 7243 EQUB 32 \ trackSectionSize \ Track section 14 EQUB %01110000 \ trackSectionFlag Sp=0 G=1 Mc=1 Mlr=10 Vc=00 Sh=0 EQUB &61 \ xTrackSectionILo xTrackSectionI = &1261 = 4705 EQUB &12 \ yTrackSectionILo yTrackSectionI = &0E12 = 3602 EQUB &9F \ zTrackSectionILo zTrackSectionI = &249F = 9375 EQUB &C5 \ xTrackSectionOLo xTrackSectionO = &11C5 = 4549 EQUB 27 \ trackSectionFrom EQUB &6B \ zTrackSectionOLo zTrackSectionO = &256B = 9579 EQUB 24 \ trackSectionSize \ Track section 15 EQUB %11101101 \ trackSectionFlag Sp=1 G=1 Mc=1 Mlr=01 Vc=10 Sh=1 EQUB &61 \ xTrackSectionILo xTrackSectionI = &1B61 = 7009 EQUB &C0 \ yTrackSectionILo yTrackSectionI = &11C0 = 4544 EQUB &77 \ zTrackSectionILo zTrackSectionI = &2B77 = 11127 EQUB &C5 \ xTrackSectionOLo xTrackSectionO = &1AC5 = 6853 EQUB 12 \ trackSectionFrom EQUB &43 \ zTrackSectionOLo zTrackSectionO = &2C43 = 11331 EQUB 36 \ trackSectionSize \ Track section 16 EQUB %00110010 \ trackSectionFlag Sp=0 G=0 Mc=1 Mlr=10 Vc=01 Sh=0 EQUB &A6 \ xTrackSectionILo xTrackSectionI = &2AA6 = 10918 EQUB &DC \ yTrackSectionILo yTrackSectionI = &15DC = 5596 EQUB &F6 \ zTrackSectionILo zTrackSectionI = &2AF6 = 10998 EQUB &63 \ xTrackSectionOLo xTrackSectionO = &2B63 = 11107 EQUB 9 \ trackSectionFrom EQUB &A2 \ zTrackSectionOLo zTrackSectionO = &2BA2 = 11170 EQUB 55 \ trackSectionSize \ Track section 17 EQUB %11101101 \ trackSectionFlag Sp=1 G=1 Mc=1 Mlr=01 Vc=10 Sh=1 EQUB &0D \ xTrackSectionILo xTrackSectionI = &3C0D = 15373 EQUB &C9 \ yTrackSectionILo yTrackSectionI = &14C9 = 5321 EQUB &D7 \ zTrackSectionILo zTrackSectionI = &17D7 = 6103 EQUB &CA \ xTrackSectionOLo xTrackSectionO = &3CCA = 15562 EQUB 11 \ trackSectionFrom EQUB &83 \ zTrackSectionOLo zTrackSectionO = &1883 = 6275 EQUB 27 \ trackSectionSize \ Track section 18 EQUB %01110010 \ trackSectionFlag Sp=0 G=1 Mc=1 Mlr=10 Vc=01 Sh=0 EQUB &6B \ xTrackSectionILo xTrackSectionI = &3A6B = 14955 EQUB &A8 \ yTrackSectionILo yTrackSectionI = &14A8 = 5288 EQUB &7C \ zTrackSectionILo zTrackSectionI = &0C7C = 3196 EQUB &17 \ xTrackSectionOLo xTrackSectionO = &3B17 = 15127 EQUB 39 \ trackSectionFrom EQUB &BE \ zTrackSectionOLo zTrackSectionO = &0BBE = 3006 EQUB 38 \ trackSectionSize \ Track section 19 EQUB %01101101 \ trackSectionFlag Sp=0 G=1 Mc=1 Mlr=01 Vc=10 Sh=1 EQUB &35 \ xTrackSectionILo xTrackSectionI = &2D35 = 11573 EQUB &28 \ yTrackSectionILo yTrackSectionI = &1128 = 4392 EQUB &76 \ zTrackSectionILo zTrackSectionI = &0076 = 118 EQUB &E1 \ xTrackSectionOLo xTrackSectionO = &2DE1 = 11745 EQUB 38 \ trackSectionFrom EQUB &B8 \ zTrackSectionOLo zTrackSectionO = &FFB8 = -72 EQUB 8 \ trackSectionSize \ Track section 20 EQUB %00110000 \ trackSectionFlag Sp=0 G=0 Mc=1 Mlr=10 Vc=00 Sh=0 EQUB &E7 \ xTrackSectionILo xTrackSectionI = &29E7 = 10727 EQUB &AC \ yTrackSectionILo yTrackSectionI = &11AC = 4524 EQUB &C6 \ zTrackSectionILo zTrackSectionI = &FEC6 = -314 EQUB &28 \ xTrackSectionOLo xTrackSectionO = &2A28 = 10792 EQUB 7 \ trackSectionFrom EQUB &CF \ zTrackSectionOLo zTrackSectionO = &FDCF = -561 EQUB 28 \ trackSectionSize \ Track section 21 EQUB %11101101 \ trackSectionFlag Sp=1 G=1 Mc=1 Mlr=01 Vc=10 Sh=1 EQUB &37 \ xTrackSectionILo xTrackSectionI = &1D37 = 7479 EQUB &A0 \ yTrackSectionILo yTrackSectionI = &14A0 = 5280 EQUB &62 \ zTrackSectionILo zTrackSectionI = &FB62 = -1182 EQUB &78 \ xTrackSectionOLo xTrackSectionO = &1D78 = 7544 EQUB 9 \ trackSectionFrom EQUB &6B \ zTrackSectionOLo zTrackSectionO = &FA6B = -1429 EQUB 10 \ trackSectionSize \ Track section 22 EQUB %00101010 \ trackSectionFlag Sp=0 G=0 Mc=1 Mlr=01 Vc=01 Sh=0 EQUB &F2 \ xTrackSectionILo xTrackSectionI = &18F2 = 6386 EQUB &09 \ yTrackSectionILo yTrackSectionI = &1509 = 5385 EQUB &9E \ zTrackSectionILo zTrackSectionI = &FC9E = -866 EQUB &34 \ xTrackSectionOLo xTrackSectionO = &1834 = 6196 EQUB 20 \ trackSectionFrom EQUB &F1 \ zTrackSectionOLo zTrackSectionO = &FBF1 = -1039 EQUB 38 \ trackSectionSize \ Track section 23 EQUB %11110011 \ trackSectionFlag Sp=1 G=1 Mc=1 Mlr=10 Vc=01 Sh=1 EQUB &EC \ xTrackSectionILo xTrackSectionI = &0CEC = 3308 EQUB &97 \ yTrackSectionILo yTrackSectionI = &1497 = 5271 EQUB &D4 \ zTrackSectionILo zTrackSectionI = &09D4 = 2516 EQUB &2E \ xTrackSectionOLo xTrackSectionO = &0C2E = 3118 EQUB 22 \ trackSectionFrom EQUB &27 \ zTrackSectionOLo zTrackSectionO = &0927 = 2343 EQUB 17 \ trackSectionSize \ Track section 24 EQUB %01000100 \ trackSectionFlag Sp=0 G=1 Mc=0 Mlr=00 Vc=10 Sh=0 EQUB &D0 \ xTrackSectionILo xTrackSectionI = &05D0 = 1488 EQUB &99 \ yTrackSectionILo yTrackSectionI = &1599 = 5529 EQUB &0B \ zTrackSectionILo zTrackSectionI = &0A0B = 2571 EQUB &7E \ xTrackSectionOLo xTrackSectionO = &067E = 1662 EQUB 0 \ trackSectionFrom EQUB &50 \ zTrackSectionOLo zTrackSectionO = &0950 = 2384 EQUB 36 \ trackSectionSize \ Track section 25 EQUB %01110000 \ trackSectionFlag Sp=0 G=1 Mc=1 Mlr=10 Vc=00 Sh=0 EQUB &70 \ xTrackSectionILo xTrackSectionI = &F970 = -1680 EQUB &23 \ yTrackSectionILo yTrackSectionI = &1923 = 6435 EQUB &83 \ zTrackSectionILo zTrackSectionI = &FE83 = -381 EQUB &1E \ xTrackSectionOLo xTrackSectionO = &FA1E = -1506 EQUB 37 \ trackSectionFrom EQUB &C8 \ zTrackSectionOLo zTrackSectionO = &FDC8 = -568 EQUB 57 \ trackSectionSize \ Track section 26 EQUB %11101101 \ trackSectionFlag Sp=1 G=1 Mc=1 Mlr=01 Vc=10 Sh=1 EQUB &D8 \ xTrackSectionILo xTrackSectionI = &E5D8 = -6696 EQUB &3C \ yTrackSectionILo yTrackSectionI = &193C = 6460 EQUB &41 \ zTrackSectionILo zTrackSectionI = &EC41 = -5055 EQUB &86 \ xTrackSectionOLo xTrackSectionO = &E686 = -6522 EQUB 15 \ trackSectionFrom EQUB &86 \ zTrackSectionOLo zTrackSectionO = &EB86 = -5242 EQUB 25 \ trackSectionSize \ Track section 27 EQUB %11000010 \ trackSectionFlag Sp=1 G=1 Mc=0 Mlr=00 Vc=01 Sh=0 EQUB &15 \ xTrackSectionILo xTrackSectionI = &DB15 = -9451 EQUB &E6 \ yTrackSectionILo yTrackSectionI = &16E6 = 5862 EQUB &CA \ zTrackSectionILo zTrackSectionI = &EDCA = -4662 EQUB &64 \ xTrackSectionOLo xTrackSectionO = &DA64 = -9628 EQUB 1 \ trackSectionFrom EQUB &11 \ zTrackSectionOLo zTrackSectionO = &ED11 = -4847 EQUB 27 \ trackSectionSize \ Track section 28 EQUB %01000000 \ trackSectionFlag Sp=0 G=1 Mc=0 Mlr=00 Vc=00 Sh=0 EQUB &98 \ xTrackSectionILo xTrackSectionI = &D398 = -11368 EQUB &9A \ yTrackSectionILo yTrackSectionI = &179A = 6042 EQUB &D9 \ zTrackSectionILo zTrackSectionI = &F7D9 = -2087 EQUB &A5 \ xTrackSectionOLo xTrackSectionO = &D2A5 = -11611 EQUB 29 \ trackSectionFrom EQUB &8C \ zTrackSectionOLo zTrackSectionO = &F78C = -2164 EQUB 51 \ trackSectionSize EQUB &70 \ This byte appears to be unusedName: Track section data (Part 2 of 2) [Show more] Type: Variable Category: Extra tracks Summary: Data for the track sections Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
Brands Hatch consists of the following track sections: 0 -> Clearways to Paddock Bend (3/3) 1 -> Paddock Bend 2 |->| Paddock Bend to Druids (1/2) 3 {} Paddock Bend to Druids (2/2) 4 |->| Druids 5 || Druids to Graham Hill Bend 6 <- Graham Hill Bend 7 || Graham Hill Bend to Surtees (1/3) 8 <- Graham Hill Bend to Surtees (2/3) 9 <- Graham Hill Bend to Surtees (3/3) 10 <- Surtees 11 {} Surtees to Hawthorns Bend (1/4) 12 |->| Surtees to Hawthorns Bend (2/4) 13 {} Surtees to Hawthorns Bend (3/4) 14 {} Surtees to Hawthorns Bend (4/4) 15 -> Hawthorns Bend 16 || Hawthorns Bend to Westfield 17 -> Westfield 18 {} Westfield to Dingle Dell Corner (1/3) 19 -> Westfield to Dingle Dell Corner (2/3) 20 || Westfield to Dingle Dell Corner (3/3) 21 -> Dingle Dell Corner 22 || Dingle Dell Corner to Stirlings 23 <- Stirlings 24 {} Stirlings to Clearways (1/2) 25 {} Stirlings to Clearways (2/2) 26 -> Clearways 27 -> Clearways to Paddock Bend (1/3) 28 -> Clearways to Paddock Bend (2/3) where each section is one of the following shapes: || is a straight section that doesn't curve to the left or right, and has the same gradient throughout the whole section {} is a straight section in the sense that it doesn't curve to the left or right, but the gradient can differ between sub-sections -> consists of sub-sections that all curve to the right <- consists of sub-sections that all curve to the left |->| consists of sub-sections that are either straight or curve to the right |<-| consists of sub-sections that are either straight or curve to the left |<->| consists of sub-sections that are either straight or curve to the left or right This part defines the following aspects of these track sections: trackSectionFlag Various flags for the track section The abbreviations in brackets are used to show the values of section's flags in the comments below * Bit 0: Section shape (Sh) * 0 = straight section (only one segment vector) * 1 = curved section (multiple segment vectors) * Bit 1: Colour of left verge marks (Vc) * 0 = black-and-white verge marks * 1 = red-and-white verge marks * Bit 2: Colour of right verge marks (Vc) * 0 = black-and-white verge marks * 1 = red-and-white verge marks * Bit 3: Show corner markers on right (Mlr) * 0 = do not show corner markers to the right of the track * 1 = show corner markers to the right of the track * Bit 4: Show corner markers on left (Mlr) * 0 = do not show corner markers to the left of the track * 1 = show corner markers to the left of the track * Bit 5: Corner marker colours (Mc) * 0 = show all corner markers in white * 1 = show corner markers in red or white, as appropriate * Bit 6: Enable hooks to generate segment vectors (G) * 0 = disable HookDataPointers and HookSegmentVector * 1 = enable HookDataPointers and HookSegmentVector * Bit 7: Section has a maximum speed (Sp) * 0 = this section has no maximum speed * 1 = this section has a maximum speed xTrackSectionILo Low byte of the x-coordinate of the starting point of the inner verge of each track section yTrackSectionILo Low byte of the y-coordinate of the starting point of the inner verge of each track section zTrackSectionILo Low byte of the z-coordinate of the starting point of the inner verge of each track section xTrackSectionOLo Low byte of the x-coordinate of the starting point of the outside verge of each track section trackSectionFrom The number of the first segment vector in each section, which enables us to fetch the segment vectors for a given track section (note that because the segment vectors in this track are dynamically generated, this value points to the position in the segment vector table where the section's first vector will be stored once it is generated) zTrackSectionOLo Low byte of the z-coordinate of the starting point of the outside verge of each track section trackSectionSize The length of each track section in terms of segments.HookSlopeJump BNE slop1 \ If A is non-zero, skip the following (so the hook has \ no effect when the car is off the ground) \ If we get here then heightAboveTrack = 0, so the car \ is on the ground LDA playerSpeedHi \ Set A = the high byte of the current speed JSR MultiplyHeight \ Set: \ \ A = A * yTrackSegmentI \ = playerSpeedHi * yTrackSegmentI \ \ The value given in yTrackSegmentI is the y-coordinate \ of the segment vector, i.e. the vector from this \ segment to the next, which is the same as the change \ in height as we move through the segment \ \ So this value is higher with greater speed and on \ segments that have higher slopes BPL slop1 \ If A is positive, skip the following instruction DEC W \ Decrement W to &FF, so (W A) has the correct sign .slop1 ASL A \ Implement the shifts that we overwrote with the call ROL W \ to the hook routine, so we have effectively inserted \ the above code into the main game RTS \ Return from the subroutine EQUB &00, &00 \ These bytes appear to be unusedName: HookSlopeJump [Show more] Type: Subroutine Category: Extra tracks Summary: Jump the car when driving fast over sloping segments Deep dive: Secrets of the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * ModifyGameCode (Part 3 of 3) calls HookSlopeJump
This routine is called from part 5 of ApplyElevation to jump the car off the ground when driving fast over sloping segments. If the car is on the ground, replace the heightAboveTrack * 4 part of the car's y-coordinate calculation with playerSpeedHi * yTrackSegmentI * 4, to give: (yPlayerCoordTop yPlayerCoordHi) = (ySegmentCoordIHi ySegmentCoordILo) + carProgress * yTrackSegmentI + playerSpeedHi * yTrackSegmentI * 4 + 172 So driving fast over sloping segments can make the car jump.
Arguments: A Current value of heightAboveTrackEQUB 29 * 8Name: trackSectionCount [Show more] Type: Variable Category: Extra tracks Summary: The total number of track sections * 8 Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source fileEQUB 40Name: trackVectorCount [Show more] Type: Variable Category: Track data Summary: The total number of segment vectors in the segment vector tables Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source fileEQUW 914 \ Segments are numbered from 0 to 913Name: trackLength [Show more] Type: Variable Category: Track data Summary: The length of the full track in terms of segments Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
The highest segment number is this value minus 1, as segment numbers start from zero.EQUW 914 - 914 \ The starting line is at segment 0Name: trackStartLine [Show more] Type: Variable Category: Track data Summary: The segment number of the starting line Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
This is the segment number of the starting line, expressed as the number of segments from the starting line to the start of section 0, counting forwards around the track. If the starting line is at segment n, this value is the track length minus n.EQUB &32 \ Set class to Novice if slowest lap time > 1:32 EQUB &28 \ Set class to Amateur if slowest lap time > 1:28 EQUB 0 \ Otherwise set class to ProfessionalName: trackLapTimeSec [Show more] Type: Variable Category: Extra tracks Summary: Lap times for adjusting the race class (seconds) Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
If the slowest lap time is a human player, and it's slower than one of these times, then we change the race class to the relevant difficulty. This figure is stored in Binary Coded Decimal (BCD).EQUB 1 \ Set class to Novice if slowest lap time > 1:32 EQUB 1 \ Set class to Amateur if slowest lap time > 1:28 EQUB 0 \ Otherwise set class to ProfessionalName: trackLapTimeMin [Show more] Type: Variable Category: Extra tracks Summary: Lap times for adjusting the race class (minutes) Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
If the slowest lap time is a human player, and it's slower than one of these times, then we change the race class to the relevant difficulty.EQUB 103 \ Reverse EQUB 0 \ Neutral EQUB 103 \ First gear EQUB 74 \ Second gear EQUB 60 \ Third gear EQUB 50 \ Fourth gear EQUB 44 \ Fifth gearName: trackGearRatio [Show more] Type: Variable Category: Extra tracks Summary: The gear ratio for each gear Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
The rev count is calculated by multiplying the track gear ratio by the current speed, so lower gears correspond to more revs at the same wheel speed when compared to higher gears.EQUB 161 \ Reverse EQUB 0 \ Neutral EQUB 161 \ First gear EQUB 116 \ Second gear EQUB 93 \ Third gear EQUB 79 \ Fourth gear EQUB 68 \ Fifth gearName: trackGearPower [Show more] Type: Variable Category: Extra tracks Summary: The power for each gear Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
The engine torque is calculated by multiplying the rev count by the power for the relevant gear, so lower gears create more torque at the same rev count when compared to higher gears.EQUB 134 \ Base speed for Novice EQUB 146 \ Base speed for Amateur EQUB 152 \ Base speed for ProfessionalName: trackBaseSpeed [Show more] Type: Variable Category: Extra tracks Summary: The base speed for each race class, used when generating the best racing lines and non-player driver speeds Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source fileEQUB 5Name: trackStartPosition [Show more] Type: Variable Category: Extra tracks Summary: The starting race position of the player during a practice or qualifying lap Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source fileEQUB 37Name: trackCarSpacing [Show more] Type: Variable Category: Extra tracks Summary: The spacing between the cars at the start of a qualifying lap, in segments Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source fileEQUB 70Name: trackTimerAdjust [Show more] Type: Variable Category: Extra tracks Summary: Adjustment factor for the speed of the timers to allow for fine-tuning of time on a per-track basis Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
The value of the timerAdjust variable in the main game code is incremented on every iteration of the main driving loop. When it reaches the value in trackTimerAdjust, the timers add 18/100 of a second rather than 9/100 of a second. Increasing this value therefore speeds up the timers, allowing their speed to be adjusted on a per-track basis. Setting this value to 255 disables the timer adjustment.EQUB 0Name: trackRaceSlowdown [Show more] Type: Variable Category: Extra tracks Summary: Slowdown factor for non-player drivers in the race Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
Reduce the speed of all cars in a race by this amount (this does not affect the speed during qualifying). I suspect this is used for testing purposes..HookFirstSegment JSR MoveToNextVector \ Move to the next to the next segment vector along the \ track and update the pointers JMP CalcSegmentVector \ Calculate the segment vector for the current segment \ and put it in the xSegmentVectorI, ySegmentVectorI, \ zSegmentVectorI, xSegmentVectorO and zSegmentVectorO \ tables, returning from the subroutine using a tail \ call EQUB &00 \ This byte appears to be unusedName: HookFirstSegment [Show more] Type: Subroutine Category: Extra tracks Summary: Move to the next to the next segment vector along the track and calculate the segment vector Deep dive: Secrets of the extra tracks Dynamic track generation in the extra tracks Code hooks in the extra tracksContext: See this subroutine on its own page References: This subroutine is called as follows: * newContentHi calls HookFirstSegment * newContentLo calls HookFirstSegment
This routine is called from GetFirstSegment so we do the following when fetching the first segment in a section: * Move to the next to the next segment vector along the track * Update the sub-section and sub-section segment pointers accordingly * Calculate the track segment vector on-the-fly for curved sections This ensures that the first segment is set up correctly..CallTrackHook JMP ModifyGameCode \ Modify the main game codeName: CallTrackHook [Show more] Type: Subroutine Category: Extra tracks Summary: The track file's hook code Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this subroutine on its own page References: No direct references to this subroutine in this source file.trackChecksum EQUB &87 \ Counts the number of data bytes ending in %00 EQUB &D4 \ Counts the number of data bytes ending in %01 EQUB &78 \ Counts the number of data bytes ending in %10 EQUB &52 \ Counts the number of data bytes ending in %11Name: trackChecksum [Show more] Type: Variable Category: Extra tracks Summary: The track file's checksum Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file.trackGameName EQUS "REVS" \ Game nameName: trackGameName [Show more] Type: Variable Category: Extra tracks Summary: The game name Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
This string is checked by the loader to see whether a track file has been loaded (and if not, it loads one)..trackName EQUS "Brands Hatch" \ Track name EQUB 13 EQUB &DC, &20 \ These bytes appear to be unused EQUB &22, &20 EQUB &42, &52 EQUB &41, &4E EQUB &44, &53 EQUB &20, &48 EQUB &41, &54 EQUB &43, &48 EQUB &22, &2C EQUB &22, &20 EQUB &44, &4F EQUB &4E, &49 EQUB &4E, &47 EQUB &54, &4F EQUB &4E, &20 EQUB &50, &41 EQUB &52, &4B EQUB &22, &2C EQUB &22, &20 EQUB &4F, &55 EQUB &4C, &54 EQUB &4F, &4E EQUB &20, &50 EQUB &41, &52 EQUB &4B, &20 EQUB &20, &20 EQUB &22, &2C EQUB &22, &20 EQUB &53, &4E EQUB &45, &54 EQUB &54, &45 EQUB &52, &54 EQUB &4F, &4E EQUB &20, &20 EQUB &20, &20 EQUB &22, &0D EQUB &04, &06 EQUB &0A, &20 EQUB &DC, &22 EQUB &22, &20 EQUB &20, &0D EQUB &04, &10 EQUB &24, &20 EQUB &F4, &20 EQUB &50, &72 EQUB &6F, &67 EQUB &72, &61 EQUB &6D, &73 EQUB &20, &6F EQUB &6E, &20 EQUB &74, &68 EQUB &65, &20 EQUB &64, &69 EQUB &73, &63 EQUB &20, &6F EQUB &72, &20 EQUB &74, &61 EQUB &70, &65 EQUB &20, &0D EQUB &04, &1A EQUB &11, &20 EQUB &DC, &42 EQUB &20, &2C EQUB &44, &20 EQUB &2C, &4F EQUB &20, &2C EQUB &53, &20 EQUB &0D, &04 EQUB &24, &0E EQUB &20, &DC EQUB &22, &22 EQUB &20, &20 EQUB &20, &20 EQUB &20, &20 EQUB &0D, &FFName: trackName [Show more] Type: Variable Category: Extra tracks Summary: The track name Deep dive: The track data file format The extra tracks data file format The Brands Hatch trackContext: See this variable on its own page References: No direct references to this variable in this source file
This string is shown on the loading screen.SAVE "3-assembled-output/BrandsHatch.bin", CODE%, P%Save BrandsHatch.bin
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Configuration variable Absolute16Bit
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Configuration variable Absolute8Bit
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Subroutine CalcSegmentVector (category: Extra tracks)
Calculate the segment vector for the current segment
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Configuration variable CheckVergeOnScreen
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Subroutine Hook80Percent (category: Extra tracks)
Set the horizonTrackWidth to 80% of the width of the track on the horizon
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Subroutine HookDataPointers (category: Extra tracks)
If the current section is dynamically generated, update the data pointers
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Subroutine HookFieldOfView (category: Extra tracks)
When populating the verge buffer in GetSegmentAngles, don't give up so easily when we get segments outside the field of view
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Subroutine HookFirstSegment (category: Extra tracks)
Move to the next to the next segment vector along the track and calculate the segment vector
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Subroutine HookFixHorizon (category: Extra tracks)
Apply the horizon line in A instead of horizonLine
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Subroutine HookFlattenHills (category: Extra tracks)
Flatten any hills in the verge buffer, calculate the hill height and track width, cut objects off at the hill height
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Subroutine HookFlipAbsolute (category: Extra tracks)
Set the sign of A according to the direction we are facing along the track
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Subroutine HookJoystick (category: Extra tracks)
Apply enhanced joystick steering to specific track sections
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Subroutine HookMoveBack (category: Extra tracks)
Only move the player backwards if the player has not yet driven past the segment
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Subroutine HookSectionFrom (category: Extra tracks)
Initialise and calculate the current segment vector
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Subroutine HookSegmentVector (category: Extra tracks)
If the current section is dynamically generated, move to the next segment vector, calculate it and store it
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Subroutine HookSlopeJump (category: Extra tracks)
Jump the car when driving fast over sloping segments
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Subroutine HookUpdateHorizon (category: Extra tracks)
Only update the horizon if we have found fewer than 12 visible segments
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Subroutine ModifyGameCode (Part 1 of 3) (category: Extra tracks)
Modify the game code to support the extra track data
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Configuration variable MovePlayerBack
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Subroutine MoveToNextVector (category: Extra tracks)
Move to the next to the next segment vector along the track and update the pointers
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Configuration variable Multiply8x8
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Subroutine Multiply8x8Signed (category: Extra tracks)
Multiply two 8-bit numbers, one of which is signed
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Configuration variable MultiplyHeight
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Subroutine SetSegmentVector (category: Extra tracks)
Add the yaw angle and height deltas to the yaw angle and height (for curved sections) and calculate the segment vector
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Configuration variable T
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Configuration variable U
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Subroutine UpdateDataPointers (category: Extra tracks)
Update the sub-section and segment numbers to point to the next segment along the track in the correct direction
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Configuration variable UpdateVectorNumber
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Configuration variable V
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Configuration variable W
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Configuration variable blockOffset
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Label coll1 in subroutine HookFixHorizon
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Label coll2 in subroutine HookFixHorizon
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Configuration variable currentPlayer
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Configuration variable directionFacing
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Label flab1 in subroutine HookDataPointers
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Label flag1 in subroutine HookSegmentVector
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Label fovw1 in subroutine HookFieldOfView
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Label from1 in subroutine HookSectionFrom
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Configuration variable frontSegmentIndex
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Configuration variable gseg13
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Label hill1 in subroutine HookFlattenHills
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Label hill2 in subroutine HookFlattenHills
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Label hill3 in subroutine HookFlattenHills
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Configuration variable horizonLine
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Configuration variable horizonListIndex
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Label joys1 in subroutine HookJoystick
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Variable modifyAddressHi (category: Extra tracks)
High byte of the location in the main game code where we modify a two-byte address
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Variable modifyAddressLo (category: Extra tracks)
Low byte of the location in the main game code where we modify a two-byte address
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Label mods1 in subroutine ModifyGameCode (Part 1 of 3)
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Label mods2 in subroutine ModifyGameCode (Part 2 of 3)
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Label mods3 in subroutine ModifyGameCode (Part 3 of 3)
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Variable newContentHi (category: Extra tracks)
High byte of the two-byte address that we want to poke into the main game code at the modify location
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Variable newContentLo (category: Extra tracks)
Low byte of the two-byte address that we want to poke into the main game code at the modify location
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Configuration variable objTrackSection
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Configuration variable playerPastSegment
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Configuration variable playerSpeedHi
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Configuration variable segmentCounter
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Variable segmentSlope (category: Extra tracks)
The height above ground of the current track sub-section
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Label sets1 in subroutine SetSegmentVector
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Label slop1 in subroutine HookSlopeJump
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Variable subSection (category: Extra tracks)
The number of the current sub-section
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Variable subSectionSegment (category: Extra tracks)
The number of the segment within the current sub-section, counting from the start of the sub-section
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Configuration variable thisSectionFlags
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Configuration variable thisVectorNumber
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Configuration variable topTrackLine
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Configuration variable trackSectionFrom
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Variable trackSignData (category: Track data)
Base coordinates and object types for 16 road signs
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Variable trackSlope (category: Extra tracks)
The slope at the start of each track section
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Variable trackSlopeDelta (category: Extra tracks)
The change in the slope (i.e. the change in the gradient) over the course of each segment for each sub-section of the track
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Variable trackSteering (category: Extra tracks)
The optimum steering for non-player drivers on each track section
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Variable trackSubConfig (category: Extra tracks)
Configuration data for each section that defines the sub-section numbers, and horizon calculations
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Variable trackSubCount (category: Extra tracks)
The total number of sub-sections in the track
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Variable trackSubSize (category: Extra tracks)
The size of each sub-section, i.e. the number of segments in each sub-section
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Configuration variable trackWidth
Track width
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Variable trackYawAngleHi (category: Extra tracks)
The high byte of the yaw angle of the start of each track section (i.e. the direction of the track at that point)
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Variable trackYawAngleLo (category: Extra tracks)
The low byte of the yaw angle of the start of each track section (i.e. the direction of the track at that point)
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Variable trackYawDeltaHi (category: Extra tracks)
High byte of the change in yaw angle that we apply to each segment in the specified sub-section when building the track
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Variable trackYawDeltaLo (category: Extra tracks)
Low byte of the change in yaw angle that we apply to each segment in the specified sub-section when building the track
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Label upda1 in subroutine UpdateDataPointers
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Label upda2 in subroutine UpdateDataPointers
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Label upda3 in subroutine UpdateDataPointers
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Label upho1 in subroutine HookUpdateHorizon
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Label vect1 in subroutine CalcSegmentVector
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Label vect2 in subroutine CalcSegmentVector
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Label vect3 in subroutine CalcSegmentVector
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Label vect4 in subroutine CalcSegmentVector
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Label vect5 in subroutine CalcSegmentVector
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Configuration variable vergeBufferEnd
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Configuration variable xStore
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Variable xTrackCurve (category: Extra tracks)
The x-coordinate of the tangent vector (i.e. the curve direction) at 64 points on a one-eighth circle covering 0 to 45 degrees
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Configuration variable xTrackSegmentI
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Configuration variable xTrackSegmentO
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Variable xTrackSignVector (category: Extra tracks)
The x-coordinate of the track sign vector for each sign, to be scaled and added to the inner track section vector for the sign
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Configuration variable xVergeLeftHi
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Configuration variable xVergeLeftLo
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Configuration variable xVergeRightHi
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Configuration variable xVergeRightLo
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Configuration variable yStore
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Configuration variable yTrackSegmentI
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Variable yTrackSignVector (category: Extra tracks)
The y-coordinate of the track sign vector for each sign, to be scaled and added to the inner track section vector for the sign
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Configuration variable yVergeLeft
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Configuration variable yVergeRight
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Variable yawAngleHi (category: Extra tracks)
High byte of the current yaw angle of the track, i.e. the angle at which the track is pointing along the ground
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Variable yawAngleLo (category: Extra tracks)
Low byte of the current yaw angle of the track, i.e. the angle at which the track is pointing along the ground
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Variable zTrackCurve (category: Extra tracks)
The z-coordinate of the tangent vector (i.e. the curve direction) at 64 points on a one-eighth circle covering 0 to 45 degrees
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Configuration variable zTrackSegmentI
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Configuration variable zTrackSegmentO
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Variable zTrackSignVector (category: Extra tracks)
The z-coordinate of the track sign vector for each sign, to be scaled and added to the inner track section vector for the sign