From 6e1554d7aee561129b4e28d19b792b05cfca9468 Mon Sep 17 00:00:00 2001
From: Kevin Caccamo <kevin@ciinet.org>
Date: Sat, 8 May 2021 07:13:47 -0400
Subject: [PATCH] Fix mirror updates in Shadow Warrior

---
 source/games/sw/src/draw.cpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/source/games/sw/src/draw.cpp b/source/games/sw/src/draw.cpp
index 524e2ef0b..6b88ed6e3 100644
--- a/source/games/sw/src/draw.cpp
+++ b/source/games/sw/src/draw.cpp
@@ -1376,7 +1376,10 @@ void UpdateWallPortalState()
     // This is too obtuse to be maintained statically, but with 8 mirrors at most easy to be kept up to date.
     for (int i = 0; i < MAXMIRRORS; i++)
     {
-        auto wal = &wall[mirror[i].mirrorwall];
+        if (mirror[i].mirrorwall < 0) {
+            continue;
+        }
+        walltype* wal = &wall[mirror[i].mirrorwall];
         wal->portalflags = 0;
         wal->portalnum = 0;