From e6e451c0400e69b7d573cb49872d9517c419efa1 Mon Sep 17 00:00:00 2001
From: "Jasper St. Pierre" <jstpierre@mecheye.net>
Date: Sat, 9 Nov 2024 22:56:11 -0800
Subject: [PATCH] Source Engine: Fix disappearing overlays

---
 src/SourceEngine/BSPFile.ts | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/SourceEngine/BSPFile.ts b/src/SourceEngine/BSPFile.ts
index 2e8f1400b..0f72f8614 100644
--- a/src/SourceEngine/BSPFile.ts
+++ b/src/SourceEngine/BSPFile.ts
@@ -1820,6 +1820,9 @@ export class BSPFile {
             vec3.set(overlayInfo.basis[0], vecUVPoint0Z, vecUVPoint1Z, vecUVPoint2Z);
             vec3.cross(overlayInfo.basis[1], overlayInfo.normal, overlayInfo.basis[0]);
 
+            if (vecUVPoint3Z == 1.0)
+                vec3.negate(overlayInfo.basis[1], overlayInfo.basis[1]);
+
             vec2.set(overlayInfo.planePoints[0], vecUVPoint0X, vecUVPoint0Y);
             vec2.set(overlayInfo.planePoints[1], vecUVPoint1X, vecUVPoint1Y);
             vec2.set(overlayInfo.planePoints[2], vecUVPoint2X, vecUVPoint2Y);