Car geometry: ChangeDirection

       Name: ChangeDirection                                         [Show more]
       Type: Subroutine
   Category: Car geometry
    Summary: Update the track segment buffer when the player's car spins so it
             changes the direction in which it is facing along the track
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * MovePlayerSegment calls ChangeDirection
             * UpdateCurveVector calls via ChangeDirection-1


 Other entry points:

   ChangeDirection-1    Contains an RTS


.ChangeDirection

 LDA #6                 \ Set sectionListValid = 6, to invalidate the contents
 STA sectionListValid   \ of the track section list (so it gets repopulated
                        \ by the GetTrackAndMarkers routine)

 LDX #64                \ Set X = 64, so the call to TurnPlayerAround
                        \ initialises 64 track segments in the new direction

 STX debugSpinning      \ Set debugSpinning = 64 (this value is never read and
                        \ is not used anywhere, so perhaps it was used for
                        \ debugging purposes, or was left over from code that
                        \ was subsequently removed?)

 JSR TurnPlayerAround   \ Turn the player around and initialise 64 track
                        \ segments in the new direction

 LDA #0                 \ Set debugSpinning = 0 (which has no effect)
 STA debugSpinning

 RTS                    \ Return from the subroutine