From c7be67e860da6ba4a903cc7048e5714c9a7a0c90 Mon Sep 17 00:00:00 2001
From: Nihilazo <nico@itwont.work>
Date: Wed, 24 Nov 2021 08:23:56 +0000
Subject: [PATCH] sawtooth motion. I want this to become a triangle or sine
 motion.

---
 scroller.tal | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/scroller.tal b/scroller.tal
index a535b0c..c771d14 100644
--- a/scroller.tal
+++ b/scroller.tal
@@ -9,6 +9,7 @@
 %DEBUG2 { SWP ;print-hex JSR2 ;print-hex JSR2 #0a .Console/write DEO }
 
 %MOD { DIVk MUL SUB }
+%MOD2 { DIV2k MUL2 SUB2 }
 
 %RTN { JMP2r }
 
@@ -47,13 +48,21 @@ BRK
 @redraw ( -> )
 	&charpos $2
 	&run
+		;font .Screen/addr DEO2
+		#00 .Screen/sprite DEO ( clear up remnants of last one )
 		#0000 ,&charpos STR2
 		#0000 STH2
 		&loop
-			STH2rk ;text ++ LDA #00 EQU ,&end JCN
+			STH2rk ;text ADD2 LDA #00 EQU ,&end JCN
+			( draw new )
 			;font #0008 ;text STH2rk ADD2 LDA #20 SUB #00 SWP MUL2 ADD2 .Screen/addr DEO2
 			,&charpos LDR2 .scrollpos LDZ2 ADD2 .Screen/x DEO2
-			STH2rk .Screen/y DEO2
+				STH2rk 
+				.scrollpos LDZ2 
+				#0008 DIV2 ADD2
+				#0010 MOD2
+				.Screen/height DEI2 #0002 DIV2 ADD2
+				.Screen/y DEO2 ( do wave motion )
 			STH2rk SWP POP ( get low byte of counter )
 			#03 MOD #01 ADD .Screen/sprite DEO
 			STH2r #0001 ADD2 STH2 ( increment counter )
@@ -61,7 +70,7 @@ BRK
 			,&loop JMP
 		&end
 		.scrollpos LDZ2 #0000 STH2r #0008 MUL2 SUB2 EQU2 ,&resetscroll JCN
-		.scrollpos LDZ2 #0002 SUB2 .scrollpos STZ2
+		.scrollpos LDZ2 #0002 SUB2 .scrollpos STZ2 ( scroll forward )
 	BRK
 		&resetscroll
 		.Screen/width DEI2 .scrollpos STZ2