second: add tv effect for gorilla

demos/second/part08_gorilla/Makefile

@@ -17,6 +17,7 @@ GORILLA:	gorilla.o
 gorilla.o:	gorilla.s \
 	../zx02_optim.s \
 	../hgr_copy_fast.s \
+	tv_effect.s \
 	../zp.inc ../hardware.inc ../qload.inc \
 	graphics/mntscrl3.hgr.zx02
 	ca65 -o gorilla.o gorilla.s -l gorilla.lst

demos/second/part08_gorilla/gorilla.s

@@ -68,8 +68,10 @@ gorilla_wait:
 
 	; TODO: TV_shutoff effect
 
-	lda	#0
-	jsr	hgr_page1_clearscreen
+;	lda	#0
+;	jsr	hgr_page1_clearscreen
+
+	jsr	tv_effect
 
 gorilla_wait2:
 	lda	#30
@@ -89,6 +91,7 @@ gorilla_done:
 	.include	"../hgr_clear_screen.s"
 	.include	"../hgr_copy_fast.s"
 
+	.include	"tv_effect.s"
 	.include	"../irq_wait.s"
 
 gorilla_data:

demos/second/part08_gorilla/tv_effect.s

@@ -0,0 +1,117 @@
+
+	;===========================
+	; tv turning off effect
+	;===========================
+tv_effect:
+
+	ldx	#0
+	lda	#191
+	sta	COUNT			; count = bottom
+compact_loop:
+
+	stx	SAVEX			; X = top
+
+	;=======================
+	; zero out bottom line
+
+	ldx	COUNT
+
+	lda	hposn_low,X
+	sta	GBASL
+	lda	hposn_high,X
+	sta	GBASH
+
+	lda	#0
+	ldy	#39
+compact_inner_loop2:
+	sta	(GBASL),Y
+	dey
+	bpl	compact_inner_loop2
+
+	dec	COUNT
+
+	;=======================
+	; zero out top line
+
+	ldx	SAVEX
+
+compact_not_even:
+
+	lda	hposn_low,X
+	sta	GBASL
+	lda	hposn_high,X
+	sta	GBASH
+
+	lda	#0
+	ldy	#39
+compact_inner_loop:
+	sta	(GBASL),Y
+	dey
+	bpl	compact_inner_loop
+
+	lda	#10
+	jsr	wait
+
+	inx
+	cpx	#95
+	bne	compact_loop
+
+	lda	#100
+	jsr	wait
+
+	;=================================
+	; now close it down horizontally
+
+
+	ldx	#95
+	lda	hposn_low,X
+	sta	GBASL
+	lda	hposn_high,X
+	sta	GBASH
+	inx
+	lda	hposn_low,X
+	sta	OUTL
+	lda	hposn_high,X
+	sta	OUTH
+
+	lda	#39
+	sta	COUNT
+	ldy	#0
+zappo_outer_loop:
+
+	ldx	#0
+zappo_inner_loop:
+	lda	pixel_pattern_left,X
+	sta	(OUTL),Y
+	sta	(GBASL),Y
+	tya
+	pha
+
+	ldy	COUNT
+	lda	pixel_pattern_right,X
+	sta	(OUTL),Y
+	sta	(GBASL),Y
+	pla
+	tay
+
+	inx
+	cpx	#8
+	bne	zappo_inner_loop
+
+	lda	#75
+	jsr	wait
+
+	dec	COUNT
+
+	iny
+	cpy	#20
+	bne	zappo_outer_loop
+
+	rts
+
+
+pixel_pattern_left:
+	.byte	$7f,$7e,$7c,$78,$70,$60,$40,$00
+
+pixel_pattern_right:
+	.byte	$7F,$3F,$1F,$0F,$07,$03,$01,$00