GSCats/gameobject.s
2017-09-13 10:56:34 -06:00

302 lines
4.9 KiB
ArmAsm

;
; gameobject
; Code and data structures related to the game objects
;
; Created by Quinn Dunki on 8/13/17
;
GAMEOBJECTWIDTH = 8
GAMEOBJECTHEIGHT = 8
; Base class sample:
;gameobjectData:
; .word 40 ; X pos in pixels (from right terrain edge)
; .word 38 ; Y pos in pixels (from bottom terrain edge)
; .word 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0 ; Saved background
GO_POSX = 0 ; Byte offsets into gameobject data structure
GO_POSY = 2
GO_BACKGROUND = 4
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; placeGameObjectOnTerrain
;
; PARAML0 = Pointer to gameobject data
; Trashes SCRATCHL
;
placeGameObjectOnTerrain:
SAVE_AY
ldy #GO_POSX
lda (PARAML0),y
clc ; Map into reversed terrain X space
adc #GAMEOBJECTWIDTH
sta SCRATCHL
lda #TERRAINWIDTH
sec
sbc SCRATCHL
and #$fffe ; Force even
tay
lda terrainData,y
clc
adc #GAMEOBJECTHEIGHT
ldy #GO_POSY
sta (PARAML0),y
RESTORE_AY
rts
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; RENDER_GAMEOBJECT
;
; ptr = Pointer to gameobject data
; Trashes SCRATCHL
;
.macro RENDER_GAMEOBJECT ptr
.scope
SAVE_AXY
; Find gameobject location in video memory
ldy #0
; X
lda ptr+GO_POSX,y
lsr
cmp leftScreenEdge
bmi renderGameobjectSkip ; Gameobject is off left edge of screen
cmp rightScreenEdge
bpl renderGameobjectSkip ; Gameobject is off right edge of screen
sec ; Convert byte x-pos to screenspace
sbc leftScreenEdge
sta SCRATCHL
; Y
sec
lda #200
sbc ptr+GO_POSY,y
bmi renderGameobjectSkip ; Gameobject is off top edge of screen
cmp #200 - GAMEOBJECTHEIGHT
bpl renderGameobjectSkip ; Gameobject is off bottom edge of screen
asl
tax
lda vramYOffset,x
clc
adc SCRATCHL
tax ; X now contains the VRAM offset of the upper left corner
phx
bra renderGameobjectBackground
renderGameobjectSkip:
jmp renderGameobjectDone
renderGameobjectBackground:
; Save background
lda VRAM,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+2,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160+2,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*2,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*2+2,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*3,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*3+2,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*4,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*4+2,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*5,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*5+2,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*6,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*6+2,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*7,x
sta ptr+GO_BACKGROUND,y
iny
iny
lda VRAM+160*7+2,x
sta ptr+GO_BACKGROUND,y
plx
; Draw sprite
lda #$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
.endscope
.endmacro
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; UNRENDER_GAMEOBJECT
;
; ptr = Pointer to gameobject data
; Trashes SCRATCHL
;
.macro UNRENDER_GAMEOBJECT ptr
.scope
SAVE_AXY
; Find gameobject location in video memory
ldy #0
; X
lda ptr+GO_POSX,y
lsr
cmp leftScreenEdge
bmi unrenderGameobjectSkip ; Gameobject is off left edge of screen
cmp rightScreenEdge
bpl unrenderGameobjectSkip ; Gameobject is off right edge of screen
sec
sbc leftScreenEdge
sta SCRATCHL
; Y
sec
lda #200
sbc ptr+GO_POSY,y
bmi unrenderGameobjectSkip ; Gameobject is off top edge of screen
cmp #200 - GAMEOBJECTHEIGHT
bpl unrenderGameobjectSkip ; 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
bra unrenderGameobjectBackground
unrenderGameobjectSkip:
jmp unrenderGameobjectDone
unrenderGameobjectBackground:
lda ptr+GO_BACKGROUND,y
sta VRAM,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+2,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160+2,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*2,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*2+2,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*3,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*3+2,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*4,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*4+2,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*5,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*5+2,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*6,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*6+2,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*7,x
iny
iny
lda ptr+GO_BACKGROUND,y
sta VRAM+160*7+2,x
unrenderGameobjectDone:
RESTORE_AXY
.endscope
.endmacro