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Routines |
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Used by the routine at HandlerChasingNastie.
Updates the sprite ID of an actor so that it faces the way it is moving and flips its animation frame. Bit 1 of the sprite ID is set when the X velocity is positive, and bit 0 of the sprite ID is flipped.
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| FaceDirection | 42179 | LD A,(IX+6) | Fetch the X velocity of the actor. | |||||
| 42182 | RLCA | Rotate the X velocity left twice, so that the direction is in bit 1. | ||||||
| 42183 | RLCA | |||||||
| 42184 | AND %00000010 | Keep only the direction bit (bit 1). | ||||||
| 42186 | LD C,A | Stash the direction bit in C. | ||||||
| 42187 | LD A,(IX+0) | Fetch the sprite ID of the actor. | ||||||
| 42190 | AND %11111101 | Keep only bits 0 and 2-7. | ||||||
| 42192 | OR C | Merge in the direction bit. | ||||||
| 42193 | XOR %00000011 | Flip bits 0 and 1. | ||||||
| 42195 | LD (IX+0),A | Set the new sprite ID of the actor. | ||||||
| 42198 | RET | Return. | ||||||
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