Routines
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45265: Test Target Range
Return carry if this actor is close enough to its target: Jetman when he is riding the rover, otherwise the parked rover. The world X difference is scaled by 8 and must be less than 0192 and the target must be 0-31 below the actor.
Input
IX Actor slot
Handler_Missile_TestJetmanRange 45265 LD A,(24696) Fetch Jetman_Slot.
Types 18-25 are Jetman seated on the rover; use his slot. Otherwise use the rover slot when its type is in 26-41.
45268 SUB 18 Subtract 18.
45270 CP 8 Jump to Handler_Missile_FetchJetman if Jetman is seated.
45272 JR C,Handler_Missile_FetchJetman
45274 LD A,(24720) Fetch Rover_Slot.
45277 SUB 26 Subtract 26.
45279 CP 16 Jump to Handler_Missile_OutOfRange if that is not a rover frame.
45281 JR NC,Handler_Missile_OutOfRange
45283 LD HL,(24722) Fetch Rover_Position.
45286 LD A,(24724) Fetch the rover Y.
45289 LD C,A Stash it in C.
Scale both world X values and test the horizontal range.
Handler_Missile_ScaleTargetX 45290 ADD HL,HL Multiply the target world X by 8.
45291 ADD HL,HL
45292 ADD HL,HL
45293 LD E,(IX+2) Fetch the actor world X.
45296 LD D,(IX+3) Fetch the high byte.
45299 EX DE,HL Switch the pairs.
45300 ADD HL,HL Multiply the actor world X by 8.
45301 ADD HL,HL
45302 ADD HL,HL
Take the absolute horizontal distance between the two scaled X values.
45303 AND A Clear the carry flag.
45304 SBC HL,DE Subtract the target world X.
45306 LD A,H Fetch the high byte of the difference.
45307 AND A Jump to Handler_Missile_SubtractRange if the result is positive.
45308 JP P,Handler_Missile_SubtractRange
45311 CALL NegatePair Call NegatePair.
Return unless the actor is within the horizontal range.
Handler_Missile_SubtractRange 45314 LD DE,192 DE=0192.
45317 AND A Clear the carry flag.
45318 SBC HL,DE Subtract the range.
45320 RET NC Return if the actor is too far away.
Test the vertical distance to the target.
45321 LD A,(IX+4) Fetch the actor Y.
45324 SUB C Subtract the target Y.
45325 NEG Negate the difference.
45327 CP 32 Compare it against 32.
45329 RET Return.
Use Jetman's position as the target when he is seated.
Handler_Missile_FetchJetman 45330 LD HL,(24698) Fetch Jetman_Position.
45333 LD A,(24700) Fetch Jetman_Y.
45336 LD C,A Stash it in C.
45337 JR Handler_Missile_ScaleTargetX Jump to Handler_Missile_ScaleTargetX.
Handler_Missile_OutOfRange 45339 AND A Return with the carry flag clear.
45340 RET
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