Routines
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27693: Update Current Object
Used by the routine at HandlerAccelerate.
Moves the pointer at CurrentObject so that it still points to the first map point which is within 96 map units of the player's X position.
UpdateCurrentObject 27693 XOR A Write 0 to Flag_PointerMovedBack (it is set to 1 if the pointer moves back).
27694 LD (24091),A
27697 LD BC,(24089) Fetch the pointer to the first map point in view (CurrentObject).
Look at the earlier map points to see if the pointer has to move back.
UpdateCurrentObject_Back 27701 DEC BC Decrease BC by three (to the previous map point).
27702 DEC BC
27703 DEC BC
27704 LD A,(BC) Fetch the X position of the map point.
27705 LD D,A Keep the X position in D.
27706 CALL ScaleValue_DivideByEight Call ScaleValue_DivideByEight to convert it to map units in DE.
27709 CALL GetMapDistance Find how far the map point is from the player using GetMapDistance.
27712 JR NC,UpdateCurrentObject_Moved Jump to UpdateCurrentObject_Moved if the map point is not close enough.
27714 LD A,1 Write 1 to Flag_PointerMovedBack.
27716 LD (24091),A
27719 JR UpdateCurrentObject_Back Jump to UpdateCurrentObject_Back.
UpdateCurrentObject_Moved 27721 LD A,(24091) Fetch the flag which says whether the pointer moved back (Flag_PointerMovedBack).
27724 AND A Jump to UpdateCurrentObject_Forward if the pointer did not move back.
27725 JR Z,UpdateCurrentObject_Forward
27727 INC BC Increment BC by three (to the first map point which is close enough).
27728 INC BC
27729 INC BC
UpdateCurrentObject_Store 27730 LD (24089),BC Write BC to CurrentObject.
27734 RET Return.
Check whether the pointer has to move forward.
UpdateCurrentObject_Forward 27735 LD BC,(24089) Fetch the pointer to the first map point in view (CurrentObject).
27739 LD A,(BC) Fetch the X position of the map point.
27740 LD D,A Keep the X position in D.
27741 CALL ScaleValue_DivideByEight Call ScaleValue_DivideByEight to convert it to map units in DE.
27744 CALL GetMapDistance Find how far the map point is from the player using GetMapDistance.
27747 RET C Return if the map point is close enough.
UpdateCurrentObject_Closer 27748 LD (24092),HL Write the distance to PreviousDistance.
UpdateCurrentObject_NextPoint 27751 INC BC Increment BC by three (to the next map point).
27752 INC BC
27753 INC BC
27754 LD A,(BC) Fetch the X position of the map point.
27755 LD D,A Keep the X position in D.
27756 CALL ScaleValue_DivideByEight Call ScaleValue_DivideByEight to convert it to map units in DE.
27759 CALL GetMapDistance Find how far the map point is from the player using GetMapDistance.
27762 JR C,UpdateCurrentObject_Store Jump to UpdateCurrentObject_Store if the map point is close enough.
27764 PUSH HL Stash the distance on the stack.
27765 LD DE,(24092) Fetch the previous distance from PreviousDistance.
27769 AND A HL=HL - DE.
27770 SBC HL,DE
27772 POP HL Restore the distance (HL) from the stack.
27773 JR Z,UpdateCurrentObject_NextPoint Jump to UpdateCurrentObject_NextPoint if the distance is the same as before.
27775 JR C,UpdateCurrentObject_Closer Jump to UpdateCurrentObject_Closer if the map point is nearer than the previous one.
27777 RET Return.
Prev: 27646 Up: Map Next: 27778