From: Lukas Krickl <lukas@krickl.dev>
Date: Wed, 24 Sep 2025 04:27:29 +0000 (+0200)
Subject: rectangle: fixed collision breaking during scroll due to rectangle positions overflow... 
X-Git-Url: https://git.krickl.dev/?a=commitdiff_plain;h=ef497e241d48e1bf4f90ee534a52eb9744d8106b;p=gbrg%2F.git

rectangle: fixed collision breaking during scroll due to rectangle positions overflowing or underflowing
---

diff --git a/src/macros.inc b/src/macros.inc
index c0f36f3..3aa5bba 100644
--- a/src/macros.inc
+++ b/src/macros.inc
@@ -218,4 +218,28 @@ $1:
 	;		$6: w
 #macro recdef
 	.db $1, $2, $3, $4, $5, $6
+#endmacro
+	
+	; caps an underflow when carry is set
+	; caps value to 0x00
+	; inputs:
+	;		af: value and carry flag
+#macro capunderflow
+.beginscope
+	jr nc, @no_underflow REL
+		xor a, a
+@no_underflow:		
+.endscope
+#endmacro
+	
+	; caps an overflow when carry is set
+	; caps value to 0xFF
+	;	inputs:
+	;		af: value and carry flag
+#macro capoverflow
+.beginscope
+jr nc, @no_overflow REL 
+	ld a, 0xFF
+@no_overflow:
+.endscope	
 #endmacro
diff --git a/src/rectangle.s b/src/rectangle.s
index 3a3e012..c14086f 100644
--- a/src/rectangle.s
+++ b/src/rectangle.s
@@ -97,6 +97,7 @@ rect_tl:
 	ld l, a
 	ld a, d
 	sub a, l ; y-height
+	capunderflow
 	ld d, a ; d = top left y
 	ret
 	
@@ -122,6 +123,7 @@ rect_tr:
 
 	ld a, [hl]
 	add a, e ; e = x + width
+	capoverflow
 	ld e, a 
 
 	dec hl ; go back to height
@@ -129,6 +131,7 @@ rect_tr:
 	ld l, a
 	ld a, d
 	sub a, l ; y-height
+	capunderflow
 	ld d, a ; d = top right y
 	ret
 	
@@ -144,6 +147,7 @@ rect_br:
 
 	ld a, [hl]
 	add a, e ; e = x + width
+	capoverflow
 	ld e, a 
 	ret