sb: work on color cycle

games/sb/Makefile

@@ -61,7 +61,7 @@ asplode.o:	asplode.s zx02_optim.s \
 		asplode_graphics/sb_title.hgr.zx02 \
 		asplode_graphics/sb_zone.hgr.zx02 \
 		asplode_graphics/sb_sprites.inc \
-		hgr_sprite_big.s \
+		hgr_sprite_big.s cycle_colors.s \
 		zp.inc hardware.inc
 	ca65 -o asplode.o asplode.s -l asplode.lst
 

games/sb/asplode.s

@@ -43,7 +43,28 @@ load_title:
 
 	jsr	full_decomp
 
-	jsr	wait_until_keypress
+	; load to page2 for color cycle
+
+	lda	#<title_data
+	sta	ZX0_src
+	lda	#>title_data
+	sta	ZX0_src+1
+
+	lda	#$40
+
+	jsr	full_decomp
+
+title_cycle_loop:
+
+	jsr	cycle_colors
+	inc	FRAME
+
+
+	lda	KEYPRESS
+	bpl	title_cycle_loop
+
+	bit	KEYRESET
+
 
 	;===================
 	; setup game
@@ -166,6 +187,7 @@ wait_until_keypress:
 	.include	"hgr_tables.s"
 	.include	"zx02_optim.s"
 	.include	"hgr_sprite_big.s"
+	.include	"cycle_colors.s"
 
 	.include	"asplode_graphics/sb_sprites.inc"
 

games/sb/cycle_colors.s

@@ -0,0 +1,69 @@
+
+; used for title of strongbadzone
+
+cycle_colors:
+
+	lda	FRAME
+	lsr
+	lsr
+	lsr
+	and	#$3
+	tax
+
+	lda	color_opcodes,X
+	sta	color_change1_smc
+	sta	color_change2_smc
+
+	lda	color_mask_odd,X
+	sta	color_change1_smc+1
+
+	lda	color_mask_even,X
+	sta	color_change2_smc+1
+
+
+	ldx	#50
+color_loop:
+
+	lda	hposn_high,X
+	sta	OUTH
+	eor	#$60
+	sta	INH
+
+	lda	hposn_low,X
+	sta	OUTL
+	sta	INL
+
+	ldy	#39
+
+color_inner_loop:
+
+
+	lda	(INL),Y
+color_change1_smc:
+	and	#$AA
+	sta	(OUTL),Y
+	dey
+
+	lda	(INL),Y
+color_change2_smc:
+	and	#$55
+	sta	(OUTL),Y
+	dey
+
+
+	bpl	color_inner_loop
+
+	dex
+	bne	color_loop
+
+
+	rts
+
+
+
+color_opcodes:
+	.byte	$29,$29,$09,$29		; and = $29  ora=$09
+color_mask_odd:
+	.byte	$AA,$7f,$00,$D5
+color_mask_even:
+	.byte	$D5,$7f,$00,$AA