.RotateCarToCoord LDY #6 \ Set Y = 6, so in the call to RotateVector, variableY \ is xPlayerAccel and variableY+1 is zPlayerAccel LDA #3 \ Set A = 3, so in the call to RotateVector, we store \ the result in xAcceleration and zAcceleration LDX #%01000000 \ Set bit 6 and clear bit 7 of X, to set the polarity in \ the call to RotateVector \ Fall through into RotateVector to calculate the \ following: \ \ xAcceleration = xPlayerAccel * cosYawAngle \ + zPlayerAccel * sinYawAngle \ \ zAcceleration = zPlayerAccel * cosYawAngle \ - xPlayerAccel * sinYawAngleName: RotateCarToCoord [Show more] Type: Subroutine Category: Maths (Geometry) Summary: Rotate a vector from the frame of reference of the player's car into the 3D world coordinate system Deep dive: The core driving modelContext: See this subroutine in context in the source code References: This subroutine is called as follows: * ApplyDrivingModel calls RotateCarToCoord
Calculate the following: [ xAcceleration ] [ cosYawAngle 0 sinYawAngle ] [ xPlayerAccel ] [ - ] = [ 0 1 0 ] . [ - ] [ zAcceleration ] [ -sinYawAngle 0 cosYawAngle ] [ zPlayerAccel ] This rotates the xPlayerAccel vector from the frame of reference of the player's car into the 3D world coordinate system. The rotation matrix is the transpose of the matrix from RotateCoordToCar, which is the inverse, so the RotateCarToCoord routine reverses the rotation in the RotateCoordToCar routine. The individual calculations are as follows: xAcceleration = xPlayerAccel * cosYawAngle + zPlayerAccel * sinYawAngle zAcceleration = zPlayerAccel * cosYawAngle - xPlayerAccel * sinYawAngle