Apple-2gs-SW/iigs-game-engine
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Fix sprite VBUFF offset calculation

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This commit is contained in:
Lucas Scharenbroich 2022-02-21 15:58:16 -06:00
parent e0912c8956
commit 56bfdc4236
2 changed files with 13 additions and 7 deletions
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5
demos/zelda/App.Main.s
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@ -123,7 +123,6 @@ EvtLoop
bne :not_q
brl Exit
:not_q
brl EvtLoop
cmp #'d'
bne :not_d
@ -182,10 +181,10 @@ EvtLoop
lda vsync
beq :no_vsync
:vsyncloop jsl GetVerticalCounter ; 8-bit value
cmp ScreenY1
cmp ScreenY0
bcc :vsyncloop
sec
sbc ScreenY1
sbc ScreenY0
cmp #8
bcs :vsyncloop ; Wait until we're within the top 8 scanlines
lda #1

15
src/Sprite2.s
View File

@ -114,12 +114,12 @@ _MarkDirtySprite
txa
and #$0007
pha
sta tmp0 ; save to adjust sprite origin
lda _Sprites+SPRITE_CLIP_HEIGHT,y ; Nominal value between 0 and 16+7 = 23 = 10111
dec
clc
adc 1,s
adc tmp0
and #$0018
sta AreaIndex
@ -138,12 +138,12 @@ _MarkDirtySprite
txa
and #$0003
sta 1,s
sta tmp1 ; save to adjust sprite origin
lda _Sprites+SPRITE_CLIP_WIDTH,y ; max width = 8 = 0x08
dec
clc
adc 1,s
adc tmp1
lsr ; max value = 4 = 0x04
and #$0006
ora AreaIndex
@ -160,6 +160,12 @@ _MarkDirtySprite
lda :stamp_step,x
clc
adc _Sprites+VBUFF_ADDR,y
sec
sbc tmp1 ; Subtract the horizontal within-tile displacement
asl tmp0
ldx tmp0
sec
sbc :vbuff_mul,x
sta VBuffOrigin
lda #^TileStore
sta tmp1
@ -174,6 +180,7 @@ _MarkDirtySprite
dw mdsOut,mdsOut,mdsOut,mdsOut
:stamp_step dw 0,12,24,36
:vbuff_mul dw 0,52,104,156,208,260,312,364
; Dispatch to the calculated sizing
; Begin a list of subroutines to cover all of the valid sprite size combinations. This is all unrolled code,