From 6019b8b96a0f8bfce53ec92c3bdf9e33c9a84678 Mon Sep 17 00:00:00 2001
From: James R <justsomejames2@gmail.com>
Date: Fri, 2 Jun 2023 16:09:47 -0700
Subject: [PATCH] R_ProjectSprite: fix overflow in sideways perspective
 clipping

Multiplications of perspective values can easily overflow
and flip sign bit at far distances. Instead, divide the
left operand.
---
 src/r_things.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/r_things.cpp b/src/r_things.cpp
index adb407973..f37ced90f 100644
--- a/src/r_things.cpp
+++ b/src/r_things.cpp
@@ -2037,7 +2037,7 @@ static void R_ProjectSprite(mobj_t *thing)
 			tz2 = FixedMul(MINZ, this_scale);
 		}
 
-		if (tx2 < -(FixedMul(tz2, fovtan[viewssnum])<<2) || tx > FixedMul(tz, fovtan[viewssnum])<<2) // too far off the side?
+		if ((tx2 / 4) < -(FixedMul(tz2, fovtan[viewssnum])) || (tx / 4) > FixedMul(tz, fovtan[viewssnum])) // too far off the side?
 			return;
 
 		yscale = FixedDiv(projectiony[viewssnum], tz);