Routines
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43681: Handle Clockwork Mouse
The update routine for the clockwork mouse (objects 116 to 119), which is deadly to touch. It runs along one axis for a random number of passes in IX+16, or until it hits something. Then it chooses a new random speed and turns through a right angle, alternating between the x and y axes. The sprite number says which way it faces, and the flip flag says which axis it uses.
Input
IX The address of the object
Move the mouse, or choose a new direction.
HandleClockworkMouse 43681 CALL SetPixelAdjustments_Mouse Call SetPixelAdjustments_Mouse.
43684 CALL ApplyGravityAndMove Call ApplyGravityAndMove.
43687 LD A,(IX+9) Jump to HandleClockworkMouse_ChooseDirection if the mouse is not moving.
43690 OR (IX+10)
43693 JR Z,HandleClockworkMouse_ChooseDirection
43695 LD A,(IX+12) Fetch the collision flags.
43698 AND %00000011 Keep bits 0 and 1.
43700 JR NZ,HandleClockworkMouse_ChooseDirection Jump to HandleClockworkMouse_ChooseDirection if the mouse has hit something.
43702 DEC (IX+16) Count down the remaining passes.
43705 JR Z,HandleClockworkMouse_ChooseDirection Jump to HandleClockworkMouse_ChooseDirection if they have run out.
Animate the mouse and redraw it.
HandleClockworkMouse_Animate 43707 CALL ToggleSpriteNumber Call ToggleSpriteNumber.
43710 JP SetDeadlyFlagsAndDraw Jump to SetDeadlyFlagsAndDraw.
Choose a new direction.
HandleClockworkMouse_ChooseDirection 43713 CALL PlayHighBeep Call PlayHighBeep.
43716 LD A,(23299) Fetch 23299.
43719 LD C,A Keep it in C.
43720 LD A,(23301) Fetch RandomSeed2.
43723 XOR C Combine the two.
43724 AND %00001111 Keep bits 0 to 3.
43726 LD (IX+16),A Set the remaining passes.
43729 LD A,(IX+7) Fetch the flags of the mouse.
43732 XOR %01000000 Flip bit 6.
43734 LD (IX+7),A Store the flags.
43737 LD A,(23301) Fetch RandomSeed2.
43740 AND %00000001 Keep bit 0.
43742 JR Z,HandleClockworkMouse_CheckFlippedForward Jump to HandleClockworkMouse_CheckFlippedForward if it is zero.
43744 BIT 6,(IX+7) Jump to HandleClockworkMouse_ChooseSpeed if the mouse is not flipped.
43748 JR Z,HandleClockworkMouse_ChooseSpeed
Turn the mouse round.
HandleClockworkMouse_TurnRound 43750 LD A,(IX+0) Fetch the sprite number.
43753 XOR %00000010 Flip bit 1.
43755 LD (IX+0),A Store the sprite number.
Choose a speed of 2 to 5.
HandleClockworkMouse_ChooseSpeed 43758 LD A,(23298) Fetch FrameCounter.
43761 AND %00000011 Keep bits 0 and 1.
43763 ADD A,2 Add 2.
43765 BIT 1,(IX+0) Jump to HandleClockworkMouse_CheckFlipped if the mouse is facing forwards.
43769 JR NZ,HandleClockworkMouse_CheckFlipped
43771 NEG Make the speed negative.
HandleClockworkMouse_CheckFlipped 43773 BIT 6,(IX+7) Jump to HandleClockworkMouse_NegativeSpeed if the mouse is flipped.
43777 JR NZ,HandleClockworkMouse_NegativeSpeed
43779 LD (IX+9),A Set the speed along the x axis.
43782 LD (IX+10),0 Write 0 as the speed along the y axis.
43786 JR HandleClockworkMouse_Animate Jump to HandleClockworkMouse_Animate.
HandleClockworkMouse_CheckFlippedForward 43788 BIT 6,(IX+7) Jump to HandleClockworkMouse_TurnRound if the mouse is not flipped.
43792 JR Z,HandleClockworkMouse_TurnRound
43794 JR HandleClockworkMouse_ChooseSpeed Jump to HandleClockworkMouse_ChooseSpeed.
HandleClockworkMouse_NegativeSpeed 43796 NEG Make the speed negative.
43798 LD (IX+10),A Set the speed along the y axis.
43801 LD (IX+9),0 Write 0 as the speed along the x axis.
43805 JR HandleClockworkMouse_Animate Jump to HandleClockworkMouse_Animate.
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