| ← CDB1 | Map | CE27 → |
CDE8: UFO behavior handler
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Runs the UFO each frame. Nothing reaches it in the shipped game. No wave script and no handler spawns the UFO. This handler therefore never runs. What follows is what it would do.
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Unlike the face monster, it neither wanders nor avoids walls. Each frame it forces a fixed horizontal heading straight toward the bat's losing edge, and glides across. It dies on a ball kill (50 points). It despawns at the far edge. A sweep hit restarts its animation and starts the death sequence.
Heading select: leftward when the bat plays on the left, rightward when it plays on the right. Those headings therefore always point across the field toward the bat.
Animation: two wing sprites alternate, each shown for 4 frames.
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| update_ufo | CDE8 | CALL inhabitant_react_state | Run the reaction-state step; carry skips the rest while a spawn or death animation plays. |
| CDEB | RET C | ||
| CDEC | LD A,(bat_side) | Pick the heading from the bat side. The bat on the right takes the next case, and the bat on the left jumps to the leftward case. | |
| CDEF | OR A | ||
| CDF0 | JR NZ,ufo_head_left | ||
| CDF2 | LD A,$02 | Bat on the right: head rightward, toward it. | |
| CDF4 | JR ufo_set_heading | ||
| ufo_head_left | CDF6 | LD A,$06 | Bat on the left: head leftward, toward it. |
| ufo_set_heading | CDF8 | LD (IY+$00),A | Store the chosen heading in the UFO's logic record. |
| CDFB | LD HL,anim_ufo | Animate from the UFO's frame table. Each of the two sprites holds two table entries, so each stays up for two animation steps. Wrap the animation frame at the table's end. | |
| CDFE | CALL advance_anim | ||
| CE01 | LD A,(IY+$0B) | ||
| CE04 | CP $04 | ||
| CE06 | JR C,ufo_move | ||
| CE08 | LD (IY+$0B),$00 | ||
| ufo_move | CE0C | CALL move_object | Advance one step along the fixed heading and publish the heading code. There is no wander or wall-avoidance. |
| CE0F | CALL inhabitant_offscreen | Despawn at the far edge. | |
| CE12 | RET C | ||
| CE13 | LD B,$05 | Ball kill: a ball overlap kills it for 50 points, banked into the pending score. | |
| CE15 | CALL ball_kill | ||
| CE18 | RET C | ||
| CE19 | CALL overlap_sweep | The sweep hits: restart the animation and start the death sequence (no score). | |
| CE1C | OR A | ||
| CE1D | RET Z | ||
| CE1E | LD (IY+$0B),$00 | ||
| CE22 | LD (IY+$0C),$02 | ||
| CE26 | RET | ||
| ← CDB1 | Map | CE27 → |