Maths (Geometry): AddVectors

       Name: AddVectors                                              [Show more]
       Type: Subroutine
   Category: Maths (Geometry)
    Summary: Add two three-axis vectors together
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * BuildCarObjects (Part 3 of 3) calls AddVectors
             * GetTrackSegment (Part 3 of 3) calls AddVectors


 Given a three-axis variable vectorX and a three-axis variable vectorY, this
 routine calculates the following addition:

                       [ (SS T) ]
   vectorX = vectorY + [ (TT U) ]
                       [ (UU V) ]


 Arguments:

   X                    The offset of the vectorX variable to update:

                          * Index * 3 of the track segment to use for the
                            section coordinates for the inner track

                          * &F4 = xHelmetCoord

                          * &FA = xCoord1

                          * &FD = xCoord2

   Y                    The offset of the vectorY variable to add:

                          * Index * 3 of the track segment to use for the
                            section coordinates for the inner track

                          * &F4 = xHelmetCoord

                          * &FA = xCoord1

                          * &FD = xCoord2

   (SS T)               The value to add to the first axis

   (TT U)               The value to add to the second axis

   (UU V)               The value to add to the third axis


.AddVectors

 LDA xSegmentCoordILo,Y \ Set xVectorX = xVectorY + (SS T)
 CLC                    \
 ADC T                  \ starting with the low bytes
 STA xSegmentCoordILo,X

 LDA xSegmentCoordIHi,Y \ And then the high bytes
 ADC SS
 STA xSegmentCoordIHi,X

 LDA ySegmentCoordILo,Y \ Set yVectorX = yVectorY + (TT U)
 CLC                    \
 ADC U                  \ starting with the low bytes
 STA ySegmentCoordILo,X

 LDA ySegmentCoordIHi,Y \ And then the high bytes
 ADC TT
 STA ySegmentCoordIHi,X

 LDA zSegmentCoordILo,Y \ Set zVectorX = zVectorY + (UU V)
 CLC                    \
 ADC V                  \ starting with the low bytes
 STA zSegmentCoordILo,X

 LDA zSegmentCoordIHi,Y \ And then the high bytes
 ADC UU
 STA zSegmentCoordIHi,X

 RTS                    \ Return from the subroutine