Routines
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52497: Run Frame
Used by the routine at RunGame.
Runs one frame of the game. First the timers are updated and then the player is controlled, updated and projected. The view is scrolled, the other entities are updated, and then the draw list is built, sorted and drawn. Finally the messages are updated.
The counter in JumpCounter is used for the player jumping and for the death of the player. Purpose of its values is not yet known.
Count down the timer, if it is running.
RunFrame 52497 LD A,(41695) Fetch the countdown timer.
52500 AND A Test it.
52501 JR Z,RunFrame_Gauge Jump to RunFrame_Gauge if it has stopped.
52503 DEC A Decrease the timer by one and store it.
52504 LD (41695),A
Drain the first gauge by 16 and redraw it. If it has run out then the player bursts, provided that it is still the player.
RunFrame_Gauge 52507 LD HL,(42399) Fetch the target of the first gauge.
52510 LD DE,16 Set the amount to drain, 16.
52513 AND A Take the amount away.
52514 SBC HL,DE
52516 JR C,RunFrame_Burst Jump to RunFrame_Burst if the gauge has run out.
52518 LD (42399),HL Store the new target of the gauge.
52521 LD IX,42397 Point IX at Gauges.
52525 CALL UpdateGauge Move the bar of the gauge one step towards its target.
52528 JR RunFrame_Spawn Jump to RunFrame_Spawn.
RunFrame_Burst 52530 LD A,(46400) Fetch the type of the player entity.
52533 DEC A Decrease it by one.
52534 JR NZ,RunFrame_Spawn Jump to RunFrame_Spawn if it is not of type 1.
52536 LD IX,46400 Point IX at Entities.
52540 CALL StartBurst Burst the player.
Update the points where creatures appear, on every fourth frame.
RunFrame_Spawn 52543 LD A,(41693) Fetch the frame counter.
52546 AND %00000011 Use bits 0-1.
52548 CALL Z,UpdateSpawnPoints Update the spawn points if this is a fourth frame.
Control the player, if it is still an entity of type 1. Animate it, and update the direction gauge if the heading has changed.
RunFrame_Player 52551 LD IX,46400 Point IX at Entities.
52555 LD A,(IX+0) Fetch the type of the player entity.
52558 DEC A Decrease it by one.
52559 JP NZ,RunFrame_Draw Jump to RunFrame_Draw if the player is not of type 1.
52562 CALL ControlPlayer Read the controls and turn or speed up the player.
52565 CALL AnimateEntity Animate the player.
52568 LD A,(IX+17) Fetch the heading of the player.
52571 XOR (IX+34) Find which bits of it have changed since the heading that is shown on the gauge.
52574 AND %00111111 Keep the bits that give the direction.
52576 CALL NZ,UpdateDirectionGauge Update the direction gauge if the heading has changed.
Count the frames of the counter at JumpCounter, if it is running. Purpose of its values from 1 to 5 is not yet known; the player is held still for them, and the values from 240 on are the player landing.
RunFrame_Counter 52579 LD A,(23808) Fetch the counter.
52582 AND A Test it.
52583 JR Z,RunFrame_Ground Jump to RunFrame_Ground if it is not running.
52585 INC A Add one to the counter.
52586 LD (23808),A Store it.
52589 CP 240 Jump to RunFrame_Fall if the player is landing.
52591 JR NC,RunFrame_Fall
52593 CP 2 Jump to SettlePlayer to settle the player and set the landing frame if it is 2.
52595 JP Z,SettlePlayer
52598 SUB 5 Take away 5.
52600 JR NZ,SettlePlayer_Continue Settle the player if the counter is not at 5.
52602 LD (23808),A Stop the counter.
52605 CALL PlayShortRisingSweep Play the short rising sweep.
52608 JR RunFrame_Update Jump to RunFrame_Update.
Move the player. If it is on the ground then it is not animated.
RunFrame_Ground 52610 BIT 7,(IX+30) Jump to RunFrame_Update if it is not on the ground.
52614 JR Z,RunFrame_Update
52616 CALL MoveEntity Move the player.
52619 JR RunFrame_Entities Jump to RunFrame_Entities.
RunFrame_Update 52621 LD E,(IX+31) Fetch the height of the player above the ground before it moves.
52624 PUSH DE Stash it on the stack.
52625 CALL MoveEntity Move the player.
52628 POP DE Restore the old height.
52629 LD A,(IX+30) Read field 30 of the player.
52632 AND %00111111 Use bits 0-5.
52634 JR NZ,RunFrame_Entities Jump to RunFrame_Entities if any of them are set.
52636 LD A,(IX+31) Fetch the new height of the player above the ground.
52639 AND A Test it.
52640 JR Z,RunFrame_Still Jump to RunFrame_Still if the player is on the ground.
Choose the frame of the player from its height above the ground.
52642 LD B,2 Use frame 2 if the player is lower than it was.
52644 CP E Compare the new height with the old height.
52645 JR C,RunFrame_SetFrame Jump to RunFrame_SetFrame if it is lower.
52647 LD B,3 Use frame 3 if the height is less than 4.
52649 CP 4 Jump to RunFrame_SetFrame if the height is below 4.
52651 JR C,RunFrame_SetFrame
52653 LD B,1 Use frame 1 if the height is less than 12.
52655 CP 12 Jump to RunFrame_SetFrame if the height is below 12.
52657 JR C,RunFrame_SetFrame
52659 INC B Use frame 2 if the height is less than 16.
52660 CP 16 Jump to RunFrame_SetFrame if the height is below 16.
52662 JR C,RunFrame_SetFrame
52664 LD B,4 Use frame 4 if the height is less than 22.
52666 CP 22 Jump to RunFrame_SetFrame if the height is below 22.
52668 JR C,RunFrame_SetFrame
52670 LD B,2 Otherwise use frame 2.
52672 JR RunFrame_SetFrame Jump to RunFrame_SetFrame.
The player is on the ground. If it was in the air a moment ago it has just landed, so start the counter at 240.
RunFrame_Still 52674 OR E Combine the old height with the new height.
52675 JR Z,RunFrame_Entities Jump to RunFrame_Entities if the player was already on the ground.
52677 LD A,240 Start the counter for the player landing.
52679 LD (23808),A Store it.
52682 JR RunFrame_Frame Jump to RunFrame_Frame.
RunFrame_Fall 52684 CALL MoveEntity Move the player.
Choose the frame of the player from the counter of the landing, which is frame 1 until the counter reaches 242 and then frame 3. The counter is stopped after 243.
RunFrame_Frame 52687 LD B,1 Use frame 1.
52689 LD A,(23808) Fetch the counter.
52692 CP 242 Jump to RunFrame_SetFrame if it is lower.
52694 JR C,RunFrame_SetFrame
52696 LD B,3 Use frame 3.
52698 SUB 243 Take away 243.
52700 JR NZ,RunFrame_SetFrame Jump to RunFrame_SetFrame if the landing has not finished.
52702 LD (23808),A Stop the counter.
52705 JR RunFrame_SetFrame Jump to RunFrame_SetFrame.
This entry point is used by the routine at SettlePlayer.
RunFrame_Land 52707 LD B,3 Use frame 3.
Show the frame of the player, and set the size of its sprite, if it has changed.
RunFrame_SetFrame 52709 LD A,(IX+1) Read field 1 of the player.
52712 LD C,A Keep it in C.
52713 AND %00011111 Keep the number of the frame.
52715 CP B Compare it with the new frame.
52716 JR Z,RunFrame_Entities Jump to RunFrame_Entities if it has not changed.
52718 LD A,C Fetch the flags in field 1.
52719 AND %11100000 Keep the flags in bits 5-7.
52721 OR B Combine them with the new frame.
52722 LD (IX+1),A Store them.
52725 CALL SetEntitySize Set the size of the sprite.
This entry point is used by the routine at SettlePlayer.
RunFrame_Entities 52728 LD A,(23774) Read the byte at GameVariable.
52731 AND %00010000 Keep bit 4.
52733 CALL NZ,CreatePuff Create an entity of type 5 if the bit is set.
Work out where the player is on the screen and scroll the view to follow it. Then update the entities and the extra records, build and sort the draw list, and draw it. If SPACE or CAPS SHIFT is pressed the game is paused here.
RunFrame_Draw 52736 CALL ProjectPlayerEntity Project the player on to the screen.
52739 LD IX,46400 Point IX at Entities.
52743 CALL ScrollView Scroll the view to follow the player.
52746 CALL UpdateEntities Update the other entities.
52749 CALL UpdateExtraRecords Update the extra records.
52752 CALL BuildDrawList Build the draw list.
52755 CALL SortDrawList Sort the draw list.
52758 CALL DrawItems Draw the items of the draw list.
52761 CALL PauseGame Pause the game if a key is pressed.
Print the message that is scrolling in or out, if there is one. It is printed in two parts, one of which is chosen by the state of the message.
52764 LD A,(52825) Fetch the state of the message.
52767 AND A Test it.
52768 JR Z,RunFrame_Message Jump to RunFrame_Message if there is no message.
52770 LD DE,52826 Point DE at ExitClosedMessages.
52773 DEC A Decrease the state by one.
52774 JR Z,RunFrame_Skip Jump to RunFrame_Skip if it is the first message.
52776 LD DE,52850 Point DE at ExitClosedMessages_Second.
RunFrame_Skip 52779 CALL PrintText Print the first part of the message.
52782 CALL PrintText Print the second part of the message.
52785 LD A,(52825) Fetch the state of the message.
52788 SRL A Halve it.
52790 LD (52825),A Store it.
RunFrame_Message 52793 CALL UpdateScreen Copy the screen buffer to the screen.
Check what has happened to the player.
52796 LD A,(46400) Fetch the type of the player entity.
52799 AND A Test it.
52800 JR NZ,RunFrame_Dead Jump to RunFrame_Dead if the player is still there.
52802 INC A The player has gone, so set A to 1.
52803 LD (43610),A Store it to show that a life has been lost.
52806 LD A,(42400) Fetch the high byte of the target of the first gauge.
52809 AND A Test it.
52810 CALL Z,ScrollTimeOutMessage Show the time out message if the gauge is empty.
52813 RET Return.
RunFrame_Dead 52814 LD A,(46402) Fetch the high byte of the x coordinate of the player.
52817 AND A Test it.
52818 RET Z Return if it is zero, which is when the player has left the level.
52819 CALL RestoreItemRows Put the rows of the screen buffer back.
52822 JP RunFrame Run the next frame.
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