From 6265f0a75df1bc3eab1f078323760ceae19c1b88 Mon Sep 17 00:00:00 2001
From: Vince Weaver <vince@deater.net>
Date: Thu, 31 Dec 2020 11:43:03 -0500
Subject: [PATCH] tfv: optimize sky drawing

glitches a bit and wasn't critical path, but much cleaner
---
 tfv/Makefile       |  3 +-
 tfv/flying_mode7.s | 99 ++++++++++++++++++++++++++--------------------
 tfv/tfv_flying.s   | 10 ++---
 tfv/zp.inc         |  4 +-
 4 files changed, 65 insertions(+), 51 deletions(-)

diff --git a/tfv/Makefile b/tfv/Makefile
index 644b8e2a..be2f7fb8 100644
--- a/tfv/Makefile
+++ b/tfv/Makefile
@@ -50,7 +50,8 @@ TFV_FLYING:	tfv_flying.o
 	ld65 -o TFV_FLYING tfv_flying.o -C ../linker_scripts/apple2_2000.inc
 
 tfv_flying.o:	tfv_flying.s \
-	gr_hlin.s gr_putsprite.s \
+	zp.inc \
+	gr_putsprite.s \
 	tfv_help.s \
 	flying_mode7.s flying_sprites.inc
 	ca65 -o tfv_flying.o tfv_flying.s -l tfv_flying.lst
diff --git a/tfv/flying_mode7.s b/tfv/flying_mode7.s
index fba66984..7ad59d30 100644
--- a/tfv/flying_mode7.s
+++ b/tfv/flying_mode7.s
@@ -7,50 +7,22 @@
 ;	2da70 cycles (added in 2 cycle cpx)  a00 = 2560, yes, 32*40=1280
 ;	2aec3 cycles (update inner loop) = 175,811 = 5.7 fps
 
+
+;	flying_loop -> check_done	2040 - 214f		2E
+;
+;	check_done -> draw_background	214f - 219b		2E
+;
+;	draw_background -> check_over_water	219b - 219e	298ad
+;
+;	check_over_water -> no_splash	219e - 21d0		5b
+;
+;	no_splash -> done_flying_loop	21d0 - 229b		aa4
+
+
+
+
 draw_background_mode7:
 
-	; Only draw sky if necessary
-	; (at start, or if we have switched to text, we never overwrite it)
-
-	lda	DRAW_SKY						; 3
-	beq	no_draw_sky						;^2nt/3
-								;==============
-								;	  6
-	; Draw Sky
-	; not performance critical as this happens rarely
-
-	dec	DRAW_SKY	; usually 2 as we redraw both pages	; 5
-	lda	#COLOR_BOTH_MEDIUMBLUE	; MEDIUMBLUE color		; 2
-	sta	COLOR							; 3
-	lda	#0							; 2
-								;===========
-								;	 11
-
-sky_loop:				; draw line across screen
-	ldy	#39			; from y=0 to y=6		; 2
-	sty	V2							; 3
-	ldy	#0							; 2
-	pha								; 3
-	jsr	hlin_double		; hlin y,V2 at A	; 63+(X*16)
-	pla								; 4
-	clc								; 2
-	adc	#2							; 2
-	cmp	#6							; 2
-	bne	sky_loop						; 3/2nt
-								;=============
-								; (23+63+(X*16))*5
-	; Draw Hazy Horizon
-
-;	lda	#COLOR_BOTH_GREY	; Horizon is Grey		; 2
-	lda	#$56			; Horizon is Grey		; 2
-	sta	COLOR							; 3
-	lda	#6			; draw single line at 6/7	; 2
-	ldy	#39							; 2
-	sty	V2			; hlin	Y,V2 at A		; 3
-	ldy	#0							; 2
-	jsr	hlin_double		; hlin	0,40 at 6	; 63+(X*16)
-								;===========
-								; 63+(X*16)+14
 
 no_draw_sky:
 
@@ -413,6 +385,7 @@ nomatch:
 								;	 39
 
 	bcs	ocean_color		; bge 8				; 2nt/3
+
 	ldy	SPACEY_I						; 3
 	cpy	#$8							; 2
 								;=============
@@ -470,6 +443,7 @@ dxf_label:
 dxi_label:
 	adc	#0	; self modifying, is DX_I			; 2
 	sta	SPACEX_I						; 3
+
 								;==========
 								;	 18
 
@@ -567,6 +541,47 @@ ocean_color_outline:
 update_cache_outline:
 	rts								; 6
 
+
+
+	;======================================
+	; draw sky
+	;======================================
+	; Only draw sky if necessary
+	; (at start, or if we have switched to text, we never overwrite it)
+draw_sky:
+								;	  6
+	; Draw Sky on both pages
+	; lines 0..6
+
+
+	lda	#COLOR_BOTH_MEDIUMBLUE	; MEDIUMBLUE color		; 2
+	ldx	#39
+
+sky_loop:				; draw line across screen
+	sta	$400,X
+	sta	$480,X
+	sta	$500,X
+	sta	$800,X
+	sta	$880,X
+	sta	$900,X
+
+	dex
+	bpl	sky_loop
+
+	; Draw Hazy Horizon
+
+	lda	#$56			; Horizon is blue/grey		; 2
+	ldx	#39
+horizon_loop:				; draw line across screen
+	sta	$580,X
+	sta	$980,X
+
+	dex
+	bpl	horizon_loop
+
+	rts
+
+
 ; 8.8 fixed point
 ; should we store as two arrays, one I one F?
 fixed_sin:
diff --git a/tfv/tfv_flying.s b/tfv/tfv_flying.s
index 81fabd2f..c2bee1de 100644
--- a/tfv/tfv_flying.s
+++ b/tfv/tfv_flying.s
@@ -59,8 +59,7 @@ flying:
 	lda	#1		; slightly off North for better view of island
 	sta	ANGLE
 
-	lda	#2		; initialize sky both pages
-	sta	DRAW_SKY
+	jsr	draw_sky
 
 	lda	#4		; starts out at 4.5 altitude
 	sta	SPACEZ_I
@@ -304,8 +303,7 @@ check_help:
 
 	jsr	print_help
 
-	lda	#2
-	sta	DRAW_SKY
+	jsr	draw_sky
 
 check_done:
 
@@ -576,7 +574,7 @@ draw_ship:
 	;==================
 	; loop forever
 	;==================
-
+done_flying_loop:
 	jmp	flying_loop						; 3
 
 
@@ -653,7 +651,7 @@ grass_string:
 ;===============================================
 
 .include "gr_offsets.s"
-.include "gr_hlin.s"
+;.include "gr_hlin.s"
 .include "gr_pageflip.s"
 .include "gr_putsprite.s"
 .include "gr_fast_clear.s"
diff --git a/tfv/zp.inc b/tfv/zp.inc
index 0793786f..4d410bfb 100644
--- a/tfv/zp.inc
+++ b/tfv/zp.inc
@@ -63,8 +63,8 @@ NEGATE		=	$86			; UNUSED?
 LAST_SPACEX_I	=	$87
 LAST_SPACEY_I	=	$88
 LAST_MAP_COLOR	=	$89
-DRAW_SKY	=	$8A
-COLOR_MASK	=	$8B
+COLOR_MASK	=	$8A
+
 ;; World Map Only
 
 ODD             =     $7B