3D objects: BuildPlayerCar

       Name: BuildPlayerCar                                          [Show more]
       Type: Subroutine
   Category: 3D objects
    Summary: Build the objects for the player's car
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * MainDrivingLoop (Part 1 of 5) calls BuildPlayerCar
             * PushCarOffTrack calls via BuildPlayerCar-1


 Returns:

   xPlayerCoord         The 3D coordinates of the player's car

   playerYawAngle       The yaw angle of the player's car around the y-axis


 Other entry points:

   BuildPlayerCar-1     Contains an RTS


.BuildPlayerCar

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

 STX thisDriver         \ Set thisDriver to the driver number of the current
                        \ player

 STX objectNumber       \ Set objectNumber to the driver number of the current
                        \ player

 LDY playerSegmentIndex \ Build the car object for the current player using
 JSR BuildCarObjects    \ the player's track segment from the track segment
                        \ buffer, returning the car's 3D coordinates in xCoord2

 LDX #2                 \ We are about to copy the three axes of the resulting
                        \ vectors, so set an axis counter in X

.bpla1

 LDA xCoord2Lo,X        \ Copy the car's 3D coordinates from xCoord2 into
 STA xPlayerCoordHi,X   \ xPlayerCoord
 LDA xCoord2Hi,X
 STA xPlayerCoordTop,X

 DEX                    \ Decrement the axis counter

 BPL bpla1              \ Loop back until we have copied all three axes

 LDA playerSegmentIndex \ Set A = playerSegmentIndex + 3
 CLC                    \
 ADC #3                 \ to move on to the next track segment

 CMP #120               \ If A < 120, then we haven't reached the end of the
 BCC bpla2              \ track segment buffer, so jump to bpla2 to store the
                        \ updated value

 LDA #0                 \ We just reached the end of the track segment buffer,
                        \ so set A = 0 to wrap round to the start

.bpla2

 TAY                    \ Set Y to the updated track segment index * 3

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

 JSR BuildCarObjects    \ Build the car object for the current player using the
                        \ updated track segment, returning the object's yaw
                        \ angle in objYawAngle

 LDA objYawAngleLo,X    \ Copy the low byte of the yaw angle to playerYawAngleLo
 STA playerYawAngleLo

 LDA objYawAngleHi,X    \ Copy the high byte of the yaw angle to
 EOR directionFacing    \ playerYawAngleHi, flipping the sign of the
 STA playerYawAngleHi   \ coordinate if we are facing backwards along the track

 RTS                    \ Return from the subroutine