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Routines |
| Prev: 55516 | Up: Map | Next: 55616 |
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If an entity's "velocity factor" is equal to its height in characters plus 3 (a proxy for its mass), then it has reached its terminal velocity.
Used by the routine at 34438.
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| 55525 | LD IX,(34238) | Load IX with start address of current level's complex state data | ||
| 55529 | LD DE,13 | Load DE with 13 (as entries in complex state data are 13 bytes wide) | ||
| 55532 | LD A,(IX+0) | If first byte of entry is 255 (i.e. end marker)... | ||
| 55535 | CP 255 | ... | ||
| 55537 | RET Z | ...then return | ||
| 55538 | BIT 6,(IX+10) | If current entity's can-fall flag is reset... | ||
| 55542 | JR Z,55592 | ...then skip ahead to 55592 (advance to next entity) | ||
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Current entity's can-fall flag is set
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| 55544 | PUSH DE | Store DE | ||
| 55545 | CALL 53848 | Store room size data for current entity's current room | ||
| 55548 | POP DE | Restore DE | ||
| 55549 | LD A,(IX+6) | Load C with height (of entity defined by entry) + 3... | ||
| 55552 | SUB (IX+4) | ... | ||
| 55555 | ADD A,4 | ... | ||
| 55557 | LD C,A | ... | ||
| 55558 | LD A,(IX+12) | Load B with velocity factor... | ||
| 55561 | LD B,A | ... | ||
| 55562 | CP C | If C is less than or equal to this (i.e. "terminal velocity" reached)... | ||
| 55563 | JR NC,55569 | ...then skip ahead to 55569 | ||
| 55565 | INC A | Increase velocity factor by one and store for next pass (i.e. acceleration)... | ||
| 55566 | LD (IX+12),A | ... | ||
| 55569 | SRL B | Divide current (i.e. not increased) velocity factor by 2 | ||
| 55571 | LD A,(IX+6) | If sum of y-coordinate of entity's bottom and entity's depth is 122... | ||
| 55574 | ADD A,(IX+1) | ...(i.e. entity is at ground-level)... | ||
| 55577 | CP 122 | ... | ||
| 55579 | JR Z,55596 | ...then skip ahead to 55596 | ||
| 55581 | INC (IX+4) | Move entity down by one character... | ||
| 55584 | INC (IX+6) | ... | ||
| 55587 | CALL 55616 | Change entity's room down one if appropriate | ||
| 55590 | DJNZ 55571 | Decrease B (current velocity factor, i.e. remaining number of characters to drop entity) and if non-zero, loop back to 55571 | ||
| 55592 | ADD IX,DE | Advance IX by 13 bytes to next entry | ||
| 55594 | JR 55532 | Loop back to 55532 | ||
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Entity's position is such that sum of y-coordinate of bottom + depth = 122 (i.e. at ground-level)
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| 55596 | CALL 54768 | Check entity at IX for collision with another entity at same depth whose interaction-(11,6) flag is set... | ||
| 55599 | JR C,55610 | ...and if no collision occurred, then skip ahead to 55610 | ||
| 55601 | CP 129 | If collision was with entity of class 129 (causes other entities to start falling)... | ||
| 55603 | JR Z,55581 | ...then jump to 55581 (entity may fall down into next room) | ||
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Collision was not with entity of class 129, so need to resume collision check from current position in entities list, i.e. entity that character did collide with
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| 55605 | CALL 54871 | Resume checking entity for collision with another entity at same depth whose interaction-(11,6) flag is set... | ||
| 55608 | JR 55599 | ... | ||
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Entity has landed (i.e. is at ground-level and has not collided with a marker of class 129)
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| 55610 | RES 6,(IX+10) | Reset entity's can-fall flag as entity has landed | ||
| 55614 | JR 55592 | Loop back for next entity | ||
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