Extra tracks: HookFirstSegment

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


.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 unused