uxn

commit f5c816d2152cad99ba059ec1124802f37db4d4c7
parent 49d74b89d01fd25266f7de97498136f228759072
Author: Weeble <clockworksaint@gmail.com>
Date:   Thu, 29 Jun 2023 11:44:55 +0100

(screen.c) Fix sprite draw at screen edge

Problem - Sprites can be drawn at X/Y coordinates >= 0xfff9 to appear
partially over the left/upper screen boundary. But the dirty-rectangle
calculation doesn't account for this, so these updates will only appear
on the screen if something *else* dirties this area of the screen. This
can be observed in /projects/examples/devices/screen.tal where these
edges of the screen show stale content.

Solution - Detect wrapping and expand the dirty rectangle appropriately.
Change screen_change to take Uint16 to make sure values are truncated to
the intended range. Ignore changes that are fully off the screen.

Diffstat:
M
src/devices/screen.c
 | 
6
+++++-

1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/src/devices/screen.c b/src/devices/screen.c
@@ -25,8 +25,12 @@ static Uint8 blending[4][16] = {
 	{2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2, 2, 3, 1, 2}};
 
 static void
-screen_change(int x1, int y1, int x2, int y2)
+screen_change(Uint16 x1, Uint16 y1, Uint16 x2, Uint16 y2)
 {
+	if(x1 > uxn_screen.width && x2 > x1) return;
+	if(y1 > uxn_screen.height && y2 > y1) return;
+	if(x1 > x2) x1 = 0;
+	if(y1 > y2) y1 = 0;
 	if(x1 < uxn_screen.x1) uxn_screen.x1 = x1;
 	if(y1 < uxn_screen.y1) uxn_screen.y1 = y1;
 	if(x2 > uxn_screen.x2) uxn_screen.x2 = x2;