From 54b3aff09f06ed25da1fbab7059c0fd0e717872d 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.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/r_things.c b/src/r_things.c
index eb4e5f63b..79510bff8 100644
--- a/src/r_things.c
+++ b/src/r_things.c
@@ -1989,7 +1989,7 @@ 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);