Routines
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36102: Handler: Jetman Movement
Read the controls, spend fuel when flying, and update Jetman's facing and animation.
Input
IX Actor slot
Face Jetman from LEFT/ RIGHT, or coast the current horizontal speed toward a rest.
Handler_JetmanMovement 36102 CALL HandlerControls Call HandlerControls.
36105 BIT 1,A Jump to FaceJetmanLeft if LEFT is pressed.
36107 JP Z,FaceJetmanLeft
36110 BIT 0,A Jump to FaceJetmanRight if RIGHT is pressed.
36112 JP Z,FaceJetmanRight
36115 LD A,(IX+5) Jump to Handler_JetmanMovement_Read if the horizontal speed is zero.
36118 AND A
36119 JR Z,Handler_JetmanMovement_Read
36121 JP P,Handler_JetmanMovement_CoastRight Jump to Handler_JetmanMovement_CoastRight if Jetman is moving right.
Coast a leftward speed back toward rest.
36124 ADD A,2 Add 2 to the speed.
36126 CP 208 Jump to Handler_JetmanMovement_Grounded if it is now less than 208.
36128 JR C,Handler_JetmanMovement_Grounded
36130 CP 224 Jump to Handler_JetmanMovement_Grounded if it is at least 224.
36132 JR NC,Handler_JetmanMovement_Grounded
36134 ADD A,16 Add a further 16 to leave the mid-band.
36136 JR Handler_JetmanMovement_Grounded Jump to Handler_JetmanMovement_Grounded.
Coast a rightward speed back toward rest.
Handler_JetmanMovement_CoastRight 36138 ADD A,254 Decrease the speed by 2.
36140 CP 64 Jump to Handler_JetmanMovement_Grounded if it is now at least 64.
36142 JR NC,Handler_JetmanMovement_Grounded
36144 CP 48 Jump to Handler_JetmanMovement_Grounded if it is less than 48.
36146 JP C,Handler_JetmanMovement_Grounded
36149 SUB 16 Subtract a further 16 to leave the mid-band.
This entry point is used by the routines at FaceJetmanRight and FaceJetmanLeft.
Handler_JetmanMovement_Grounded 36151 LD (IX+5),A Write the speed to *IX+5.
Read the thrust keys while any fuel remains.
Handler_JetmanMovement_Read 36154 CALL HandlerControls Call HandlerControls.
36157 LD B,A Stash the controls in B.
36158 LD A,(24719) Jump to Handler_JetmanMovement_Gravity if FuelLevel_2 is zero.
36161 AND A
36162 JR Z,Handler_JetmanMovement_Gravity
36164 BIT 3,B Jump to ApplyJetmanUpwardThrust if UP is pressed.
36166 JP Z,ApplyJetmanUpwardThrust
36169 BIT 2,B Jump to ClearJetmanThrust if DOWN is pressed.
36171 JP Z,ClearJetmanThrust
Apply gravity when Jetman is not thrusting.
Handler_JetmanMovement_Gravity 36174 LD B,0 Clear the fuel-spend base.
36176 LD A,(IX+6) Jump to Handler_JetmanMovement_ThrustStep if the vertical thrust is negative.
36179 AND A
36180 JP M,Handler_JetmanMovement_ThrustStep
36183 CP 64 Jump to Handler_JetmanMovement_Loop if the downward thrust is already at least 64.
36185 JR NC,Handler_JetmanMovement_Loop
The gravity step is 8 (signed +8). Upward thrust uses the opposite 248.
Handler_JetmanMovement_ThrustStep 36187 LD C,8 Set the downward step to 8.
This entry point is used by the routine at ApplyJetmanUpwardThrust.
Handler_JetmanMovement_AddThrust 36189 ADD A,C Add the step to the vertical thrust.
36190 LD (IX+6),A
Convert the thrust into a Y offset and test for the ground or a crater.
Handler_JetmanMovement_Loop 36193 LD A,(IX+6) Fetch the vertical thrust.
36196 SRA A Divide it by 16.
36198 SRA A
36200 SRA A
36202 SRA A
36204 ADD A,(IX+4) Add it to Jetman's Y position.
36207 CP 64 Jump to ClearJetmanThrust if Jetman is above the play area.
36209 JP C,ClearJetmanThrust
36212 CP 176 Jump to Handler_JetmanMovement_WriteY if Jetman is still above the ground line.
36214 JR C,Handler_JetmanMovement_WriteY
Check the terrain beneath Jetman's new position.
36216 CALL ReadTerrainCell Call ReadTerrainCell.
36219 LD A,D Jump to Handler_JetmanMovement_ClampThrust if the first terrain cell is empty.
36220 AND A
36221 JR Z,Handler_JetmanMovement_ClampThrust
36223 LD A,E Jump to Handler_JetmanMovement_ClampThrust if the second terrain cell is empty.
36224 AND A
36225 JR Z,Handler_JetmanMovement_ClampThrust
36227 LD A,E Jump to LandJetman if neither cell has bit 3 set (a crater).
36228 OR D
36229 BIT 3,A
36231 JP Z,LandJetman
When the cell is empty or a crater, snap to the ground line at Y=175 and give a small upward thrust of 224 (signed -32).
Handler_JetmanMovement_ClampThrust 36234 LD (IX+6),224 Write 224 to the vertical thrust.
36238 LD A,175 A=175.
Handler_JetmanMovement_WriteY 36240 LD (IX+4),A Write the Y position to *IX+4.
Spend fuel from the horizontal speed, then redraw the gauge.
Handler_JetmanMovement_FuelFromSpeed 36243 LD A,(IX+5) Jump to Handler_JetmanMovement_HalveSpeed if the horizontal speed is positive.
36246 AND A
36247 JP P,Handler_JetmanMovement_HalveSpeed
36250 NEG Negate it so the spend uses the magnitude.
Handler_JetmanMovement_HalveSpeed 36252 SRA A Halve the speed.
36254 ADD A,B Add the fuel-spend base.
36255 SLA A Double the result.
36257 LD C,A Store the spend in BC.
36258 LD B,0
36260 LD HL,(24718) Fetch the current fuel from FuelLevel_1.
36263 LD A,H Jump to Handler_JetmanMovement_AfterFuel if the fuel has already run out.
36264 OR L
36265 JR Z,Handler_JetmanMovement_AfterFuel
36267 AND A Reset the carry flag.
Subtract the fuel expenditure from the current fuel level.
See Infinite Fuel.
Handler_JetmanMovement_SpendFuel 36268 SBC HL,BC Subtract the spend from the fuel.
36270 LD A,H Jump to Handler_JetmanMovement_AfterFuel if the high fuel byte is not zero.
36271 AND A
36272 JR NZ,Handler_JetmanMovement_AfterFuel
Queue a tune and empty the tank when the fuel is used up.
36274 LD DE,47661 DE=Tune_Out_Of_Fuel.
36277 CALL QueueTune Call QueueTune.
36280 LD HL,0 HL=0000.
Store the remaining fuel and redraw the gauge.
Handler_JetmanMovement_AfterFuel 36283 LD (24718),HL Write the remaining fuel to FuelLevel_1.
36286 LD A,H Fetch the high fuel byte.
36287 LD HL,4160 HL=4160 (gauge position).
36290 CALL DrawGauge Call DrawGauge.
Walk the 0-based sprite index: keep bits 2-7 (facing and flying/ walking) and merge bits 0-1 from the frame timer.
Handler_JetmanMovement_Animate 36293 CALL ApplyJetmanSpeed Call ApplyJetmanSpeed.
36296 LD A,(24130) Fetch GameTimer.
36299 AND %00000011 Keep only bits 0-1.
36301 LD C,A Stash the frame bits.
36302 LD A,(IX+0) Fetch the actor type.
36305 DEC A Decrease it to a 0-based sprite index.
36306 AND %11111100 Keep only bits 2-7.
36308 OR C Merge in the frame bits.
36309 INC A Restore the 1-based sprite ID.
36310 LD (IX+0),A Write it back to *IX+0.
Draw Jetman and fire the laser when FIRE is held.
Handler_JetmanMovement_Draw 36313 CALL DrawSprite Call DrawSprite.
36316 CALL ColouriseSprite Call ColouriseSprite.
36319 CALL HandlerControls Call HandlerControls.
36322 BIT 4,A Call Handler_LaserBeam if FIRE is pressed.
36324 CALL Z,Handler_LaserBeam
Queue a flying jingle on some frames.
36327 LD A,(65364) Jump to Handler_JetmanMovement_RefillFromRover if Tune_Pointer is not Tune_Buffer_End.
36330 CP 81
36332 JR NZ,Handler_JetmanMovement_RefillFromRover
36334 LD A,(24128) Fetch RandomNumber.
36337 AND %01111111 Keep only bits 0-6.
36339 JR NZ,Handler_JetmanMovement_RefillFromRover Jump to Handler_JetmanMovement_RefillFromRover if the result is not zero.
Pick a jingle from the table using the game timer and queue it.
36341 LD A,(24130) Fetch GameTimer.
36344 AND %00001110 Keep only bits 1-3.
36346 LD C,A Convert that index into BC.
36347 LD B,0
36349 LD HL,40368 Point HL at the matching entry in Jetman_Tune_Table.
36352 ADD HL,BC
36353 LD E,(HL) Fetch the tune pointer.
36354 INC HL
36355 LD D,(HL)
36356 CALL QueueTune Call QueueTune.
Refill the tank when Jetman is beside the rover, then take a platform (action key) or board (SPACE).
Handler_JetmanMovement_RefillFromRover 36359 LD A,(IX+4) Fetch Jetman's Y position.
36362 CP 168 Return if it is less than 168.
36364 RET C
Return unless the rover is on this screen and within reach.
36365 LD HL,(24698) Fetch Jetman_Position.
36368 LD DE,(24722) Fetch Rover_Position.
36372 AND A Subtract the rover position from Jetman's.
36373 SBC HL,DE
36375 LD DE,12 Add a 12 tolerance.
36378 ADD HL,DE
36379 LD A,H Fetch the high byte of the gap.
36380 AND %00011111 Keep only bits 0-4.
36382 RET NZ Return if the rover is not on this screen.
36383 LD A,L Return if the low byte is at least 24.
36384 CP 24
36386 RET NC
Refill the fuel tank.
36387 LD HL,36864 Write 36864 to FuelLevel_1.
36390 LD (24718),HL
Bit 0 of Jetman's flags is set while he is carrying an item.
36393 BIT 0,(IX+8) Return if Jetman is already carrying an item.
36397 RET NZ
36398 CALL TestActionKey Jump to Handler_JetmanMovement_TestSpace if the action key is not pressed.
36401 JR Z,Handler_JetmanMovement_TestSpace
36403 LD HL,24816 HL=World_Slot_4.
36406 LD A,(HL) Return if world slot 4 is already in use.
36407 AND A
36408 RET NZ
Type 46 is the platform Jetman now carries.
36409 LD (HL),46 Write type 46 to the slot.
36411 LD DE,7 Move to the colour byte.
36414 ADD HL,DE
36415 LD (HL),67 Write INK:MAGENTA, PAPER:BLACK (BRIGHT) to the colour.
36417 INC HL Set bit 0 of the slot flags.
36418 SET 0,(HL)
36420 INC HL Write 0 to *HL+2.
36421 INC HL
36422 LD (HL),0
36424 SET 0,(IX+8) Set bit 0 of Jetman's flags.
36428 JP SoundsTakeObject Jump to SoundsTakeObject.
Board the rover if SPACE is pressed.
Handler_JetmanMovement_TestSpace 36431 CALL TestSpaceKey Return if SPACE is not pressed.
36434 RET Z
36435 CALL PositionAndDrawSprite Call PositionAndDrawSprite.
36438 CALL BoardMoonRover Call BoardMoonRover.
36441 RET Return.
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