From 39395c40bbaf92464ea2a0aa790964a141253fd1 Mon Sep 17 00:00:00 2001
From: blondie7575 <qd@quinndunki.com>
Date: Sun, 30 Jul 2017 15:43:55 -0700
Subject: [PATCH] Working terrain scrolling

---
 gscats.2mg | Bin 819264 -> 819264 bytes
 gscats.s   |  62 ++++++++++++++++++++++++++++++++++++++++++++++-------
 terrain.s  |  37 +++++++++++++++++++++++---------
 3 files changed, 81 insertions(+), 18 deletions(-)

diff --git a/gscats.2mg b/gscats.2mg
index 74f7b94a5885822ac98644b8e8348dddd1468f17..3ff0bb82ddb12ed064c8706839996ef2873a2d43 100644
GIT binary patch
delta 437
zcmX@mV056tXhR08FbhL33&TGpEq(@u!weiC2Ge9mrlXr3*f`i2nI{MGY@eLK!?Brz
z*RPx@l4Wv4i>6UK=Ocslng<?m9_$B_hYVJp<7j1D$-tnnnsbqolENnr1%0kH?>H3r
zxfEJB)_&ml@M-eu7FoNK9Upj4PW>Qpa=`~RiQk6|5<tY-cN`zSS@pi-X!ro-o(y34
z@I(qEat|c3l98eJ14qN9$!A*>CK|9ze%rz!b%JvxL%->P2kSEqJm@{i$!X9JWE@hk
z?mab`zco(q1Sd#x?MY6E@Y++8>stK{|8pKPs9Kud`<K&Wr!SZ0e}-OOu0;$CFCH{7
ze2{s=%O$|NQc$pg8R(DxggFnLTwFIhGW})r$*_32fB~eb;a)}p1H;OP4_h-<Cd_F~
zpCOSMz|bnGaE9~55y=m1&(fczH+)K1094}3)hZb^18BpFoxR+e_4QQ~B~Kh!z;NO9
z<cYcRn**4X7&n{jN;haW+0|~cixG&KfS4JGS%8=oh}nRc9f&!Am=lP(wwvtY<~arc
D19-P!

delta 683
zcmX@mV056tXhR08Ff)S_Gs8b6ejWyf!weiC2Ge9mrlXr3*f`i2*(V3`Y@eLK!?Brz
z*RPz3k9l%Li>8kg=Ocslng<?m9_$B_hYVKsa<sCoWMEK8<6NYqq_CDl;R>h1c20#F
z4v0EUdx*L_h8z~Z*E1Y=An>bS;J^ck--iqmCiAr_XjME?SZ{jZL2onXN``(QV|@mY
z)56JV&<|uBQn2oA<y`rHj`V^P43iUEy(bs6vWj<HSo=s}Z8IlG`Pvpvh{Cn4lMlE0
z*RSL}WKgv<y>~gM$Iefjn*SMAy*TwjXr-WFf5M!H85S=WFo2{QUS}k%eE6_6V`aje
z*7OBH=eKj7I1s?_f$drPv-F0K2|%HhpEz43qh<h&Sh3TIOS8VdYN8}a&4t$q3@E_K
k1;O2XyUUDe^V!aHgUta<-i#2|gRT($&7%a#Vc;td0E|gE3IG5A

diff --git a/gscats.s b/gscats.s
index 3176d05..c67a809 100644
--- a/gscats.s
+++ b/gscats.s
@@ -30,36 +30,82 @@ mainBank2:
 	jsr colorFill
 
 	jsr generateTerrain
+
+mainGameLoop:
+	ldy mapScrollPos
 	jsr renderTerrainColumns
 
-	jsr kbdWait
-	CLASSICVIDEO
+	jsr kbdScan
 
+	lda quitRequested
+	beq mainGameLoop
+
+
+	CLASSICVIDEO
 	jml (proDOSLongJump)
 
 
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-; kbdWait
-; Waits for a keystroke
+; kbdScan
+; Processes keyboard input
 ;
-kbdWait:
+; Trashes A
+;
+
+kbdScan:
 	EMULATION
 
-kbdWaitLoop:
+kbdScanLoop:
 	lda KBD
-	bpl kbdWaitLoop
+	bpl kbdScanLoop
 	sta KBDSTROBE
 
+	cmp #(8 + $80)
+	beq kbdScanLeftArrow
+
+	cmp #(21 + $80)
+	beq kbdScanRightArrow
+
+	cmp #(32 + $80)
+	beq kbdScanSpace
 	NATIVE
+
+kbdScanDone:
 	rts
 
+kbdScanLeftArrow:
+	NATIVE
+	lda mapScrollPos
+	beq kbdScanDone
+	dec
+	sta mapScrollPos
+	bra kbdScanDone
+
+kbdScanRightArrow:
+	NATIVE
+	lda mapScrollPos
+	cmp #TERRAINWIDTH/4-80
+	beq kbdScanDone
+	inc
+	sta mapScrollPos
+	bra kbdScanDone
+
+kbdScanSpace:
+	NATIVE
+	lda #1
+	sta quitRequested
+	bra kbdScanDone
+
 
 
 
 basePalette:
 	.word $0000,$0080,$0000,$000F,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000,$0000
-
+mapScrollPos:	; 4-pixel columns
+	.word $0000
+quitRequested:
+	.word $0000
 
 .include "graphics.s"
 .include "terrain.s"
diff --git a/terrain.s b/terrain.s
index f9a06f1..89cb4a5 100644
--- a/terrain.s
+++ b/terrain.s
@@ -5,8 +5,8 @@
 ;
 
 
-TERRAINWIDTH = 320		; In pixels
-MAXTERRAINHEIGHT = 80	; In pixels
+TERRAINWIDTH = 640		; In pixels
+MAXTERRAINHEIGHT = 128	; In pixels
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; renderTerrainColumn
@@ -30,15 +30,23 @@ renderTerrainColumn:
 	sta renderTerrainColumnSMC+1
 	pha		; Cache 16-bit VRAM pointer on the stack
 
-	lda terrainData,y
+	lda terrainData,y		; Cache terrain height on the stack
 	and #$00ff
-	tax
-	inx		; Prevent x from going negative upon entry to loop
+	sta renderTerrainColumnHeight
+	ldx #0
 
 renderTerrainColumnLoop:
-	dex
+	inx
+	cpx #MAXTERRAINHEIGHT
 	beq renderTerrainColumnDone
+	cpx renderTerrainColumnHeight
+	bpl renderTerrainColumnBlack
+
 	lda #$1111
+	bra renderTerrainColumnSMC
+
+renderTerrainColumnBlack:
+	lda #$0000
 
 renderTerrainColumnSMC:
 	sta $e19c60
@@ -53,23 +61,32 @@ renderTerrainColumnDone:
 	pla
 	rts
 
-
+renderTerrainColumnHeight:
+	.word 0
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ; renderTerrainColumns
 ;
 ; This is not fast- probably only useful for debugging
 ;
+; Y = Start column
+;
+; Trashes all registers
+;
 
 renderTerrainColumns:
 	LOADPARAM24 $e1e1,$9c60
-	ldy #0
+	tya
+	clc
+	adc #80
+	sta SCRATCHL
 
 renderTerrainColumnsLoop:
 	jsr renderTerrainColumn
 	iny
-	cpy #TERRAINWIDTH/4
+	cpy SCRATCHL
 	beq renderTerrainColumnsDone
+
 	inc PARAM24
 	inc PARAM24
 	bra renderTerrainColumnsLoop
@@ -109,6 +126,6 @@ generateTerrainLoop:
 ; Terrain data, stored as height values 4 pixels wide
 
 terrainData:
-	.repeat TERRAINWIDTH/4
+	.repeat TERRAINWIDTH/2
 	.byte 0
 	.endrepeat