139 lines
2.5 KiB
ArmAsm
139 lines
2.5 KiB
ArmAsm
;
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; gameobject
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; Code and data structures related to the game objects
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;
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; Created by Quinn Dunki on 8/13/17
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;
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GAMEOBJECTWIDTH = 8
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GAMEOBJECTHEIGHT = 8
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gameobjectData:
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.word 40 ; X pos in pixels (from left terrain edge)
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.word 38 ; Y pos in pixels (from bottom terrain edge)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; renderGameobject
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;
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; PARAML0 = Pointer to gameobject data
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;
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renderGameobject:
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SAVE_AXY
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; Find gameobject location in video memory
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ldy #0
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; X
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lda (PARAML0),y
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lsr
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sec
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sbc leftScreenEdge
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bmi renderGameobjectDone ; Gameobject is off left edge of screen
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cmp #320 - GAMEOBJECTWIDTH
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bpl renderGameobjectDone ; Gameobject is off right edge of screen
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sta SCRATCHL
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; Y
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iny
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iny
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sec
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lda #200
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sbc (PARAML0),y
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bmi renderGameobjectDone ; Gameobject is off top edge of screen
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cmp #200 - GAMEOBJECTHEIGHT
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bpl renderGameobjectDone ; Gameobject is off bottom edge of screen
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asl
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tax
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lda vramYOffset,x
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clc
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adc SCRATCHL
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tax
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; X now contains the VRAM offset of the upper left corner
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lda #$FFFF
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sta VRAM,x
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sta VRAM+2,x
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sta VRAM+160,x
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sta VRAM+160+2,x
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sta VRAM+160*2,x
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sta VRAM+160*2+2,x
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sta VRAM+160*3,x
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sta VRAM+160*3+2,x
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sta VRAM+160*4,x
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sta VRAM+160*4+2,x
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sta VRAM+160*5,x
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sta VRAM+160*5+2,x
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sta VRAM+160*6,x
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sta VRAM+160*6+2,x
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sta VRAM+160*7,x
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sta VRAM+160*7+2,x
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renderGameobjectDone:
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RESTORE_AXY
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; unrenderGameobject
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;
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; PARAML0 = Pointer to gameobject data
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;
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unrenderGameobject:
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SAVE_AXY
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; Find gameobject location in video memory
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ldy #0
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; X
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lda (PARAML0),y
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lsr
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sec
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sbc leftScreenEdge
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bmi unrenderGameobjectDone ; Gameobject is off left edge of screen
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cmp #320 - GAMEOBJECTWIDTH
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bpl unrenderGameobjectDone ; Gameobject is off right edge of screen
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sta SCRATCHL
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; Y
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iny
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iny
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sec
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lda #200
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sbc (PARAML0),y
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bmi unrenderGameobjectDone ; Gameobject is off top edge of screen
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cmp #200 - GAMEOBJECTHEIGHT
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bpl unrenderGameobjectDone ; Gameobject is off bottom edge of screen
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asl
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tax
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lda vramYOffset,x
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clc
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adc SCRATCHL
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tax
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; X now contains the VRAM offset of the upper left corner
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lda #$0000
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sta VRAM,x
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sta VRAM+2,x
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sta VRAM+160,x
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sta VRAM+160+2,x
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sta VRAM+160*2,x
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sta VRAM+160*2+2,x
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sta VRAM+160*3,x
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sta VRAM+160*3+2,x
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sta VRAM+160*4,x
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sta VRAM+160*4+2,x
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sta VRAM+160*5,x
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sta VRAM+160*5+2,x
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sta VRAM+160*6,x
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sta VRAM+160*6+2,x
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sta VRAM+160*7,x
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sta VRAM+160*7+2,x
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unrenderGameobjectDone:
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RESTORE_AXY
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rts
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