Extra tracks: HookSegmentVector

       Name: 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 tracks
    Context: See this subroutine in context in the source code
 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.


.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 subroutine