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Routines |
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This causes the creature's missile to rebound off the shield at high speed. The diverted missile/bolt can even close open doors if it collides with a door handle.
Calculate the missile's new horizontal trajectory:
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| 53484 | LD A,(60096) | Maroc's horizontal (X-axis) screen position, in 4-pixel/half-character steps | ||
| 53487 | LD C,A | |||
| 53488 | LD A,(60232) | Missile's horizontal (X-axis) screen position, in 4-pixel/half-character steps | ||
| 53491 | SUB C | Subtract Maroc's position from missile position | ||
| 53492 | RLA | |||
| 53493 | SBC A,A | The RLA and SBC sets A to 0 or 255 depending on whether the missile position is to Maroc's left or right | ||
| 53494 | XOR 15 | Based on direction, sets the above calculated value at 240 (-15) or +15 | ||
| 53496 | LD C,A | |||
| 53497 | LD A,(60236) | Get the missile's existing horizontal movement speed | ||
| 53500 | ADD A,C | Add the calculated value (+/- 15) | ||
| 53501 | LD (60236),A | ...and re-store. | ||
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Calculate the missile's new vertical trajectory
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| 53504 | LD A,(60097) | Maroc's vertical (Y-axis) pixel screen position | ||
| 53507 | LD C,A | Missile's vertical (X-axis) pixel screen position | ||
| 53508 | LD A,(60234) | |||
| 53511 | SUB C | Subtract Maroc's position from missile position | ||
| 53512 | RLA | |||
| 53513 | SBC A,A | The RLA and SBC sets A to 0 or 255 depending on whether the missile position is above or below Maroc | ||
| 53514 | XOR 15 | Based on direction, sets the above calculated value at 240 (-15) or +15 | ||
| 53516 | LD C,A | |||
| 53517 | LD A,(60237) | Get the missile's existing vertical movement speed | ||
| 53520 | ADD A,C | Add the calculated value (+/- 15) | ||
| 53521 | LD (60237),A | ...and re-store. | ||
| 53524 | JR 53550 | |||
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