| ← D44B | Map | D4E8 → |
D47C: Warp-gate behavior handler
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Runs the warp gate, which sits static. Each frame its X is re-pinned to the bat's fixed edge column, read from the bat's sprite record, and its Y is held at 40. Its speed is 0, so it does not move. Animation is the 4-frame table, wrapped at frame 4.
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A ball kill destroys it for 1000 points. An overlap with the bat raises the warp flag and loads a random 2-to-5 warp countdown. The main loop then advances the level once per frame until the countdown clears. That carries the player forward 1 to 4 levels.
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| update_warp_gate | D47C | PUSH IY | Pin the X position to the bat's column; fix Y at a constant row. |
| D47E | LD IY,object_table | ||
| D482 | LD A,(IY+$00) | ||
| D485 | LD (IX+$00),A | ||
| D488 | POP IY | ||
| D48A | LD A,$28 | ||
| D48C | LD (IX+$01),A | ||
| D48F | CALL inhabitant_react_state | Reaction-state machine; while a spawn or death animation plays it returns carry and skips the rest. | |
| D492 | RET C | ||
| D493 | LD A,(bat_side) | Head away from the bat's side: leftward when the bat is on the right. | |
| D496 | OR A | ||
| D497 | JR NZ,warp_gate_bat_left | ||
| D499 | LD A,$06 | ||
| D49B | JR warp_gate_animate | ||
| warp_gate_bat_left | D49D | LD A,$02 | Bat on the left: take the rightward heading. |
| warp_gate_animate | D49F | LD (IY+$00),A | Store the heading, then advance and wrap the 4-frame animation. |
| D4A2 | LD HL,anim_warp_gate | ||
| D4A5 | CALL advance_anim | ||
| D4A8 | LD A,(IY+$0B) | ||
| D4AB | CP $04 | ||
| D4AD | JR C,warp_gate_move | ||
| D4AF | LD (IY+$0B),$00 | ||
| warp_gate_move | D4B3 | CALL move_object | Run the step, which leaves it in place at speed 0. A ball kill removes it for 1000 points, banked into the pending score. |
| D4B6 | LD B,$64 | ||
| D4B8 | CALL ball_kill | ||
| D4BB | RET C | ||
| warp_gate_bat_test | D4BC | LD A,C | Test overlap with the bat itself through the first and second overlap operands. |
| D4BD | LD (overlap_slot_1),A | ||
| D4C0 | XOR A | ||
| D4C1 | LD (overlap_slot_2),A | ||
| D4C4 | CALL overlap_pair | ||
| D4C7 | OR A | ||
| D4C8 | JR Z,warp_gate_sweep | ||
| warp_gate_advance | D4CA | LD A,$01 | On the bat overlap, raise the warp flag and load a random 2-to-5 countdown. The main loop advances the level while it counts down. |
| D4CC | LD (warp_active_flag),A | ||
| D4CF | CALL next_random | ||
| D4D2 | AND $03 | ||
| D4D4 | INC A | ||
| D4D5 | INC A | ||
| D4D6 | LD (warp_countdown),A | ||
| D4D9 | RET | ||
| warp_gate_sweep | D4DA | CALL overlap_sweep | No bat overlap: the sweep kills it. |
| D4DD | OR A | ||
| D4DE | RET Z | ||
| D4DF | LD (IY+$0B),$00 | ||
| D4E3 | LD (IY+$0C),$02 | ||
| D4E7 | RET | ||
| ← D44B | Map | D4E8 → |