Routines
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56127: Test Actor Collision
Used by the routines at Handler_Player and Handler_Actors.
Reverses the actor at a destination. On a player hit, copies the actor deltas onto Player.
Input
IY Actor record
Reverse at the destination when cell-aligned.
Test_ActorCollision 56127 LD A,(IY+8) Jump to Test_ActorCollision_Column if the horizontal delta is set.
56130 OR A
56131 JR NZ,Test_ActorCollision_Column
Test the destination row.
56133 LD A,7 Jump to Test_ActorCollision_Bounds unless the fine-Y is 7.
56135 CP (IY+3)
56138 JR NZ,Test_ActorCollision_Bounds
56140 LD A,(IY+1) Call Actor_Reverse if the row matches the destination.
56143 CP (IY+6)
56146 CALL Z,Actor_Reverse
56149 JR Test_ActorCollision_Bounds Jump to Test_ActorCollision_Bounds.
Test the destination column.
Test_ActorCollision_Column 56151 LD A,7 Jump to Test_ActorCollision_Bounds unless the fine-X is 7.
56153 CP (IY+2)
56156 JR NZ,Test_ActorCollision_Bounds
56158 LD A,(IY+0) Call Actor_Reverse if the column matches the destination.
56161 CP (IY+5)
56164 CALL Z,Actor_Reverse
Skip the hit test while jumping or falling.
Test_ActorCollision_Bounds 56167 LD A,(25616) Return if *Player_JumpTimer is set.
56170 OR A
56171 RET NZ
Require a close vertical overlap.
56172 LD A,(IY+1) Convert the actor row and fine-Y into a pixel row.
56175 ADD A,A
56176 ADD A,A
56177 ADD A,A
56178 ADD A,(IY+3)
56181 LD C,A
Convert the player row the same way.
56182 LD A,(25767) Convert the player row and fine-Y into a pixel row.
56185 LD B,A
56186 LD A,(25765)
56189 SUB 3
56191 ADD A,A
56192 ADD A,A
56193 ADD A,A
56194 ADD A,B
56195 SUB C Return unless the difference is less than 4.
56196 CP 4
56198 RET NC
Keep the gap and convert the actor column.
56199 LD D,A Keep the vertical gap in D.
56200 LD A,(IY+0) Convert the actor column and fine-X into a pixel column.
56203 DEC A
56204 DEC A
56205 ADD A,A
56206 ADD A,A
56207 ADD A,A
56208 ADD A,(IY+2)
56211 LD B,A
Build the overlap limit.
56212 LD A,(25673) Copy the footprint offset into C.
56215 LD C,A
56216 LD A,(IY+4) Write the actor pixel width plus that offset into *56237.
56219 ADD A,A
56220 ADD A,A
56221 ADD A,A
56222 ADD A,C
56223 DEC A
56224 LD (56237),A
Test the player width against the actor column.
56227 SUB C Restore the actor pixel width in C.
56228 LD C,A
56229 INC C
56230 LD A,(25672) Return unless the ranges overlap.
56233 ADD A,C
56234 SUB B
56235 DEC A
56236 CP 200
56238 RET NC
Copy the actor movement onto the player.
56239 LD A,(IY+8) Write the horizontal delta to *Player_HorizontalDelta.
56242 LD (25772),A
56245 LD A,3 Write 3 to *CollisionState.
56247 LD (25652),A
Adjust the vertical delta by the gap.
56250 LD A,(IY+9) Jump to Test_ActorCollision_Store if the vertical delta is zero.
56253 OR A
56254 JR Z,Test_ActorCollision_Store
56256 SUB D Subtract the vertical gap.
Store the vertical delta and the actor.
Test_ActorCollision_Store 56257 LD (25773),A Write the vertical delta to *Player_VerticalDelta.
56260 LD (25675),IY Write the actor pointer to *Pointer_CollidedActor.
56264 RET Return.
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