From 448aece5379d266736af467792e3437590f3c6dd Mon Sep 17 00:00:00 2001
From: alpine9000 <alex.g.brown@gmail.com>
Date: Thu, 12 May 2016 16:47:28 +1000
Subject: [PATCH] double buffered item sprites

---
 028.bs/game1.s  |  4 +++-
 028.bs/items.s  | 51 ++++++++++++++++++++++++++++++++++++-------------
 028.bs/macros.i |  5 +++++
 3 files changed, 46 insertions(+), 14 deletions(-)

diff --git a/028.bs/game1.s b/028.bs/game1.s
index 7505341..534aab2 100644
--- a/028.bs/game1.s
+++ b/028.bs/game1.s
@@ -452,11 +452,13 @@ RenderNextForegroundFrame:
 	move.l	d3,d2
 	bsr	RenderForegroundTile
 	bsr	ClearForegroundTile
-	jsr	RenderItemSprite	
+	jsr	RenderItemSprite
+	
 	add.l	#2,a2
 	add.l	#1,d3
 	cmp.l 	#FOREGROUND_PLAYAREA_HEIGHT_WORDS,d3
 	blt	.loop
+	jsr	PrepareItemSpriteData	
 	rts
 
 RenderPathway:
diff --git a/028.bs/items.s b/028.bs/items.s
index 847b16e..45a92a2 100644
--- a/028.bs/items.s
+++ b/028.bs/items.s
@@ -8,6 +8,7 @@
 	xdef DetectItemCollisions
 	xdef InitialiseItems
 	xdef SwitchItemSpriteBuffers
+	xdef PrepareItemSpriteData
 	
 DeleteItemSprite:
 	move.w	#0,ITEM_SPRITE(a1)
@@ -116,12 +117,12 @@ SwitchItemSpriteBuffers:
 	rts
 
 
-SetupItemSpriteData:	
+PrepareItemSpriteData:
 	cmp.l	#0,itemSpritesEnabled
 	bne	.enableSprites
-	move.l	#deadSprite,SPR2PTH(a6)
-	move.l	#deadSprite,SPR3PTH(a6)
-	move.l	#deadSprite,SPR4PTH(a6)	
+	move.l	#deadSprite,sprite2Pointer
+	move.l	#deadSprite,sprite3Pointer
+	move.l	#deadSprite,sprite4Pointer
 	rts
 	
 .enableSprites:	
@@ -131,6 +132,18 @@ SetupItemSpriteData:
 	dbra	d0,.loop
 	rts
 	
+SetupItemSpriteData:
+	move.l	sprite2Pointer,SPR2PTH(a6)
+	move.l	sprite3Pointer,SPR3PTH(a6)
+	move.l	sprite4Pointer,SPR4PTH(a6)
+	cmp.w	#0,spriteBufferIndex
+	beq	.zero
+	move.w	#0,spriteBufferIndex
+	rts
+.zero:
+	move.w	#ITEM_SPRITE_BYTES,spriteBufferIndex
+	rts
+	
 
 _SetupItemSpriteData:
 	;; d0 - item slot	
@@ -146,7 +159,7 @@ _SetupItemSpriteData:
 
 	move.w	ITEM_Y(a1),d2	
 	move.l	ITEM_SPRITE_ADDRESS(a1),a0
-
+	
 	cmp.w	#(ITEM_NUM_COIN_ANIMS-1)<<3,ITEM_INDEX(a1)
 	ble	.dontResetIndex
 	move.w	#0,ITEM_INDEX(a1)
@@ -158,15 +171,17 @@ _SetupItemSpriteData:
 
 	move.l	#0,d0
 	move.w	ITEM_INDEX(a1),d0
-	lsr.l	#3,d0
-	mulu.w	#ITEM_SPRITE_BYTES,d0
+	
+	lsr.l	#3,d0	
+	mulu.w	#ITEM_SPRITE_BYTES*2,d0
+	add.w	spriteBufferIndex,d0
 	add.l	d0,a0
 
 	mulu.w	#ITEM_SPRITE_VERTICAL_BYTES,d2
 	add.l	d2,a0
 
-	;; move.w	ITEM_X(a1),d0
-	move.w	ITEM_LAGX(a1),d0
+	move.w	ITEM_X(a1),d0
+	;; move.w	ITEM_LAGX(a1),d0
 	lsr.w	#FOREGROUND_SCROLL_SHIFT_CONVERT,d0 ; convert to pixels
 
 	add.w	#ITEM_SPRITE_HORIZONTAL_START_PIXELS,d0
@@ -177,19 +192,20 @@ _SetupItemSpriteData:
 	move.b	d0,1(a0)	;spriteHStart
 
 .c1:
+
 	sub.l	d2,a0	;#1*ITEM_SPRITE_VERTICAL_BYTES,a0
 	cmp.b	#ITEM_SPRITE_ARROW_INDEX,d4
 	bge	.arrowSprite
 	cmp.b	#ITEM_SPRITE_COINB_INDEX,d4
 	bge	.coinBSprite
 .coinASprite:
-	move.l	a0,SPR2PTH(a6)
+	move.l	a0,sprite2Pointer
 	bra	.done
 .coinBSprite:
-	move.l	a0,SPR3PTH(a6)
+	move.l	a0,sprite3Pointer
 	bra	.done	
 .arrowSprite:
-	move.l	a0,SPR4PTH(a6)
+	move.l	a0,sprite4Pointer
 	bra	.done	
 
 .done:
@@ -242,7 +258,16 @@ EnableItemSprites:
 itemSpritesEnabled:
 	dc.l	0
 
-
+spriteBufferIndex:
+	dc.l	0
+	
+sprite2Pointer:
+	dc.l	0
+sprite3Pointer:
+	dc.l	0
+sprite4Pointer:
+	dc.l	0	
+	
 	;; coinA
 	ItemControl item1,spriteCoinA1,1
 	ItemControl item2,spriteCoinA1,1
diff --git a/028.bs/macros.i b/028.bs/macros.i
index 21a9395..b898c8a 100644
--- a/028.bs/macros.i
+++ b/028.bs/macros.i
@@ -38,6 +38,11 @@ WaitBlitter:	macro
 
 
 ItemSprite:	macro
+	_ItemSprite \1,\2
+	_ItemSprite \1_1,\2
+	endm
+
+_ItemSprite:	macro
 \1:
 	dc.b	ITEM_SPRITE_VSTART	 ; vstart
 	dc.b	0			 ; hstart