Routines
Prev: 6E5D Up: Map Next: 6F54
6F13: Initialise Car
Used by the routine at Handler_Car_Type1.
Initialises a car with random speed, colour and position. The car starts at Y=90 (upper road) with the possibility of appearing at different X positions.
Input
IX Pointer to car sprite data
InitialiseCar 6F13 CALL GenerateRandomNumber Call GenerateRandomNumber.
6F16 AND %00000011 Keep only bits 0-1 (random speed 00-03).
6F18 INC A Increment (speed 01-04).
6F19 LD ($720C),A Write A to *CarSpeed2.
Set a random appearance delay if the room is valid.
6F1C LD A,($5FC5) A=*CurrentRoom.
6F1F OR A Jump to InitialiseCar_PickColour if the room number is zero.
6F20 JR Z,InitialiseCar_PickColour
6F22 CALL GenerateRandomNumber Call GenerateRandomNumber.
6F25 AND %00011111 Keep only bits 0-4.
6F27 OR %00000001 Set bit 0 (ensure odd value).
6F29 LD ($720E),A Write A to *CarAppearanceDelay.
Pick a random colour, but reject colour 01 (blue).
InitialiseCar_PickColour 6F2C CALL GenerateRandomNumber Call GenerateRandomNumber.
6F2F AND %00000011 Keep only bits 0-1 (random colour 00-03).
6F31 CP $01 Jump to InitialiseCar_PickColour if the colour is BLUE (pick again).
6F33 JR Z,InitialiseCar_PickColour
6F35 LD ($720A),A Write A to *CarColour.
Clear the crash timer and set the car on the upper road.
6F38 XOR A Write 00 to *CarCrashTimer.
6F39 LD ($7208),A
6F3C LD (IX+$01),$90 Write 90 to *IX+01 (front Y: upper road).
6F40 LD (IX+$05),$90 Write 90 to *IX+05 (rear Y: upper road).
6F44 LD (IX+$22),$07 Write 07 to *IX+22 (front wheel colour: white).
6F48 LD (IX+$26),$07 Write 07 to *IX+26 (rear wheel colour: white).
If the car's X position is past 64 reset it to the left.
6F4C LD A,(IX+$00) Load A with the car's X position (from *IX+00).
6F4F CP $64 Return if the car's X position is less than 64 (position is valid).
6F51 RET C
6F52 XOR A A=00 (reset X position to the left edge).
6F53 RET Return.
Prev: 6E5D Up: Map Next: 6F54