Apple-2gs-SW/iigs-game-engine
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Reference sprite updates that do not leave trails

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This commit is contained in:
Lucas Scharenbroich 2021-10-29 00:17:23 -05:00
parent 9ecc262c58
commit 11bbe7be3d
1 changed files with 27 additions and 20 deletions
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47
demos/sprites/App.Main.s
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@ -59,6 +59,12 @@ DOWN_ARROW equ $0A
; leave it alone. We are just testing the ability to merge sprite plane data into
; the play field tiles.
EvtLoop
lda PlayerX ; Move the player sprite a bit
sta PlayerXOld
inc
and #$001F
sta PlayerX
ldx PlayerX
ldy PlayerY
jsl GetSpriteVBuffAddr
@ -67,9 +73,8 @@ EvtLoop
stx PlayerLastPos ; save for erasure
jsl DrawTileSprite
; Now the sprite has been drawn. Manually update the 4 top-left tiles. Since we have not scrolled
; the screen, these are the tiles in rows 0 and 1 and columns 0 and 1. The next step is to mark
; those tiles as intersecting a sprite
; Now the sprite has been drawn. Enqueue the dirty tiles. We blindly add the potential
; dirty tiles and rely on PushDirtyTile to elimate duplicates quickly
lda PlayerX
lsr
@ -80,21 +85,19 @@ EvtLoop
ldy #1
jsr MakeDirtyTile
; If we are not aligned in the x-direction, dirty the tile in front
lda PlayerX
bit #$0003
beq :skip1
inx
ldy #0
clc
adc #3
lsr
lsr
tax
ldy #0 ; Y is fixed
jsr MakeDirtyTile
ldy #1
jsr MakeDirtyTile
:skip1
; If we transitioned to an aligned status, then mark the prior tile as dirty
lda PlayerX
bit #$0003
bne :skip2
; Add the tiles that the sprite was previously at as well.
lda PlayerXOld
lsr
lsr
@ -103,18 +106,22 @@ EvtLoop
jsr MakeDirtyTile
ldy #1
jsr MakeDirtyTile
:skip2
lda PlayerXOld
clc
adc #3
lsr
lsr
tax
ldy #0
jsr MakeDirtyTile
ldy #1
jsr MakeDirtyTile
; Let's see what it looks like!
jsl Render
lda PlayerX ; Move the player sprite a bit
sta PlayerXOld
inc
and #$001F
sta PlayerX
ldx PlayerLastPos ; Delete the sprite because it moved
jsl EraseTileSprite
; tax