From bdd5630f8d0adadd90632dff70856aba0adf5c15 Mon Sep 17 00:00:00 2001
From: Roman Fomin <rfomin@gmail.com>
Date: Mon, 27 Jan 2025 02:53:43 +0700
Subject: [PATCH] fix undefined behavior in linearsky calculation (#2157)

---
 src/r_main.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/r_main.c b/src/r_main.c
index fee2d57cd..21fbc483e 100644
--- a/src/r_main.c
+++ b/src/r_main.c
@@ -366,7 +366,11 @@ static void R_InitTextureMapping(void)
         ;
       xtoviewangle[x] = (i<<ANGLETOFINESHIFT)-ANG90;
       // [FG] linear horizontal sky scrolling
-      linearskyangle[x] = (0.5 - x / (double)viewwidth) * linearskyfactor;
+      int angle = (0.5 - x / (double)viewwidth) * linearskyfactor;
+      if (angle >= 0)
+        linearskyangle[x] = angle;
+      else
+        linearskyangle[x] = ANG90 + angle;
     }
     
   // Take out the fencepost cases from viewangletox.