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119 lines
2.0 KiB
ArmAsm
119 lines
2.0 KiB
ArmAsm
;
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; collision
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;
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; Created by Quinn Dunki on 9/2/17
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;
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rectParams:
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.word 0 ; x
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.word 0 ; y 0=terrain bottom, +y=up
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.word 0 ; w
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.word 0 ; h
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rectParams2:
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.word 0 ; x
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.word 0 ; y 0=terrain bottom, +y=up
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.word 0 ; w
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.word 0 ; h
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; intersectRectTerrain
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;
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; A => non zero if rectangle is intersecting terrain
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;
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intersectRectTerrain:
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phy
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; Convert X to words and compute horizontal extent
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; Note that X counts from right terrain edge
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lda rectParams
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and #$fffe ; Force even
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sta rectParams
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lda #TERRAINWIDTH ; Reverse X coordinate system
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sec
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sbc rectParams
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sta rectParams
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tay ; We'll need this later as an index into height data words
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sec
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sbc rectParams+4 ; Convert width to extent
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sta rectParams+4
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; Convert height to vertical extent
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lda rectParams+2
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sec
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sbc rectParams+6
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sta rectParams+6
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; Check Y bottom
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intersectRectTerrainBottomLoop:
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lda terrainData,y
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cmp rectParams+6
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bpl intersectRectTerrainYep
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dey
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dey
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cpy rectParams+4
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bpl intersectRectTerrainBottomLoop
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lda #0
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ply
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rts
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intersectRectTerrainYep:
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lda #1
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ply
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rts
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; intersectRectRect
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;
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; A => non zero if rectangle is intersecting rectangle2
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;
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intersectRectRect:
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lda rectParams+0 ; Convert widths to extents
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clc
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adc rectParams+4
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sta rectParams+4
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lda rectParams2+0
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clc
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adc rectParams2+4
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sta rectParams2+4
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lda rectParams+2 ; Convert heights to extents
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sec
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sbc rectParams+6
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sta rectParams+6
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lda rectParams2+2
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sec
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sbc rectParams2+6
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sta rectParams2+6
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lda rectParams+0 ; Past their right edge?
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cmp rectParams2+4
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bpl intersectRectRectNope
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lda rectParams+4 ; Before their left edge?
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cmp rectParams2+0
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bmi intersectRectRectNope
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lda rectParams+2 ; Past their bottom edge?
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cmp rectParams2+6
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bmi intersectRectRectNope
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lda rectParams+6 ; Before their top edge?
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cmp rectParams2+2
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bpl intersectRectRectNope
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lda #1
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rts
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intersectRectRectNope:
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lda #0
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rts
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