Routines
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B1AE: Face Direction Of Movement
Used by the routine at HandleBouncingMouse.
Sets the way a robot mouse faces to match the direction in which it is moving, if it is moving along one axis. The way it faces is held in bit 0 of its sprite number and bit 6 of its flags (see TurnMouseOneWay).
Input
IX The address of the object
Face along the axis with the larger speed.
FaceDirectionOfMovement B1AE LD A,(IX+$09) Return if the mouse is not moving.
B1B1 OR (IX+$0A)
B1B4 RET Z
B1B5 LD A,(IX+$09) Fetch the speed along the x axis.
B1B8 CP (IX+$0A) Jump to FaceDirectionOfMovement_MovingAlongY if the mouse is moving along the y axis.
B1BB JR C,FaceDirectionOfMovement_MovingAlongY
B1BD BIT 7,A Jump to FaceDirectionOfMovement_West if the mouse is moving west.
B1BF JR NZ,FaceDirectionOfMovement_West
B1C1 SET 0,(IX+$00) Set bit 0 of the sprite number.
FaceDirectionOfMovement_Unflip B1C5 RES 6,(IX+$07) Reset bit 6 of the flags.
B1C9 RET Return.
The mouse is moving west.
FaceDirectionOfMovement_West B1CA RES 0,(IX+$00) Reset bit 0 of the sprite number.
B1CE JR FaceDirectionOfMovement_Unflip Jump to FaceDirectionOfMovement_Unflip.
The mouse is moving along the y axis.
FaceDirectionOfMovement_MovingAlongY B1D0 BIT 7,(IX+$0A) Jump to FaceDirectionOfMovement_North if the mouse is moving north.
B1D4 JR Z,FaceDirectionOfMovement_North
B1D6 SET 0,(IX+$00) Set bit 0 of the sprite number.
FaceDirectionOfMovement_Flip B1DA SET 6,(IX+$07) Set bit 6 of the flags.
B1DE RET Return.
The mouse is moving north.
FaceDirectionOfMovement_North B1DF RES 0,(IX+$00) Reset bit 0 of the sprite number.
B1E3 JR FaceDirectionOfMovement_Flip Jump to FaceDirectionOfMovement_Flip.
View the equivalent code in;
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