GSCats/gameobject.s

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2017-08-13 22:36:12 +00:00
;
; gameobject
; Code and data structures related to the game objects
;
; Created by Quinn Dunki on 8/13/17
;
GAMEOBJECTWIDTH = 8
GAMEOBJECTHEIGHT = 8
gameobjectData:
.word 40 ; X pos in pixels (from left terrain edge)
.word 38 ; Y pos in pixels (from bottom terrain edge)
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; renderGameobject
;
; PARAML0 = Pointer to gameobject data
;
renderGameobject:
SAVE_AXY
; Find gameobject location in video memory
ldy #0
; X
lda (PARAML0),y
lsr
sec
sbc leftScreenEdge
bmi renderGameobjectDone ; Gameobject is off left edge of screen
cmp #320 - GAMEOBJECTWIDTH
bpl renderGameobjectDone ; Gameobject is off right edge of screen
sta SCRATCHL
; Y
iny
iny
sec
lda #200
sbc (PARAML0),y
bmi renderGameobjectDone ; Gameobject is off top edge of screen
cmp #200 - GAMEOBJECTHEIGHT
bpl renderGameobjectDone ; Gameobject is off bottom edge of screen
asl
tax
lda vramYOffset,x
clc
adc SCRATCHL
tax
; X now contains the VRAM offset of the upper left corner
lda #$FFFF
sta VRAM,x
sta VRAM+2,x
sta VRAM+160,x
sta VRAM+160+2,x
sta VRAM+160*2,x
sta VRAM+160*2+2,x
sta VRAM+160*3,x
sta VRAM+160*3+2,x
sta VRAM+160*4,x
sta VRAM+160*4+2,x
sta VRAM+160*5,x
sta VRAM+160*5+2,x
sta VRAM+160*6,x
sta VRAM+160*6+2,x
sta VRAM+160*7,x
sta VRAM+160*7+2,x
renderGameobjectDone:
RESTORE_AXY
rts