The AddSteeringForce subroutine - Revs on the BBC Micro

       Name: AddSteeringForce                                        [Show more]
       Type: Subroutine
   Category: Driving model
    Summary: Add the steering force to xVelocity or xTyreForceNose
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * ApplySteeringForce calls AddSteeringForce
             * ApplySteeringSpeed calls AddSteeringForce


 Arguments:

   X                    Called with either 8 or 10:

                          * 8: set xVelocity += xSteeringForce

                          * 10: set xTyreForceNose += xSteeringForce


.AddSteeringForce

 LDA xPlayerSpeedHi,X   \ Add (xSteeringForceHi xSteeringForceLo) to the
 CLC                    \ variable at offset X from (xPlayerSpeedTop
 ADC xSteeringForceLo   \ xPlayerSpeedHi), starting with the low bytes
 STA xPlayerSpeedHi,X

 LDA xPlayerSpeedTop,X  \ And then the high bytes
 ADC xSteeringForceHi
 STA xPlayerSpeedTop,X

 RTS                    \ Return from the subroutine

[X]

Variable xPlayerSpeedHi (category: Driving model)

High byte of the x-coordinate of the velocity vector (i.e. x-axis speed) for the player's car during this main loop iteration

[X]

Variable xPlayerSpeedTop (category: Driving model)

Top byte of the x-coordinate of the velocity vector (i.e. x-axis speed) for the player's car during this main loop iteration

[X]

Variable xSteeringForceHi (category: Driving model)

High byte of the sideways force applied by steering

[X]

Variable xSteeringForceLo (category: Driving model)

Low byte of the sideways force applied by steering