From 0e30924bb16f729b1ba574c2248110ecd6ca359d Mon Sep 17 00:00:00 2001
From: Lukas Krickl <lukas@krickl.dev>
Date: Wed, 1 Oct 2025 22:18:42 +0200
Subject: [PATCH] rectangle collision: Removed redundant point comparisons

---
 src/rectangle.s | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/src/rectangle.s b/src/rectangle.s
index 99d3a10..6bedb4e 100644
--- a/src/rectangle.s
+++ b/src/rectangle.s
@@ -165,8 +165,6 @@ rect_point_test:
 
 	; load bottom left point
 	ld a, [hl+]
-	; TODO: remove use of d2
-	ld [d2], a ; save y in d2
 	ld d, a ; d = y
 	ld a, [hl+] 
 	ld e, a ; e = x
@@ -191,13 +189,11 @@ rect_point_test:
 	ld d, a ; d = top left y
 	pop hl
 
+	; x was already tested in bottom left
+
 	ld a, b ; compare y points
 	cp a, d
 	jr c, @no_collision REL
-	ld a, c ; compare x position
-	cp a, e
-	jr c, @no_collision REL
-
 
 	
 	; top right
@@ -208,6 +204,8 @@ rect_point_test:
 	capoverflow
 	ld e, a
 
+	; top right has unique x and y positions
+
 	ld a, b ; compare y
 	cp a, d
 	jr c, @no_collision REL
@@ -218,17 +216,12 @@ rect_point_test:
 
 	; bottom right 
 
-	; remove height from y
-	; to get bottom right point
-	ld a, [d2] ; d2 = original y point
-	ld d, a
+	; original y position was already tested in bottom left
+	; x positions was already tested in top right
 
-	ld a, b ; compare y
-	cp a, d
-	jr nc, @no_collision REL
-	ld a, c ; compare x
-	cp a, e
-	jr nc, @no_collision REL
+	; all other missing x/y checks have 
+	; already been performed in previous points
+	; e.g. original y is tested in bottom left
 
 @collision:
 	ld a, 1
-- 
2.30.2