Car geometry: MovePlayer

       Name: MovePlayer                                              [Show more]
       Type: Subroutine
   Category: Car geometry
    Summary: Move the player's car forwards or backwards by one segment
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * MovePlayerBack calls MovePlayer
             * MovePlayerForward calls MovePlayer


 Arguments:

   C flag               Controls the direction of movement:

                          * Clear = move the car in the direction it is pointing
                            (i.e. drive forwards)

                          * Set = reverse the car


.MovePlayer

 LDX currentPlayer      \ Set X to the driver number of the current player

 ROR A                  \ If just one of the C flag and bit 7 of directionFacing
 EOR directionFacing    \ is set (but not both), jump to play1 to move the car
 BMI play1              \ backwards along the track
                        \
                        \ In other words, we move backwards if:
                        \
                        \   * C is clear and the car is facing backwards along
                        \     the track, in which case it is driving forwards
                        \     but going backwards around the track
                        \
                        \   * C is set and the car is facing forwards along the
                        \     track, in which case it is reversing along the
                        \     track while facing forwards

 JSR MoveObjectForward  \ Move the current player forwards by one segment

 RTS                    \ Return from the subroutine

.play1

 JSR MoveObjectBack     \ Move current player backwards by one segment

 RTS                    \ Return from the subroutine