Cache brush surface texture numbers instead of re-marshaling them on each access. Fixes textures getting mixed up on brush model entities after map switch.

Assets/Scripts/Data/QTexture.cs

@@ -45,7 +45,7 @@ public class QGLTexture
     
     // Conveniently make use of the fact that texNum is the first field in QGLTexture,
     // so we don't have to marshal the entire struct to get the texture number out of it.
-    public static uint TexNumFromPtr(IntPtr ptr) => ptr == IntPtr.Zero ? 0 : unchecked((uint)Marshal.ReadInt32(ptr));
+    public static uint TexNumFromPtr(IntPtr ptr) => ptr != IntPtr.Zero ? (uint)Marshal.ReadInt32(ptr) : 0;
 }
 
 /// <summary>

Assets/Scripts/Game/GameState.cs

@@ -51,10 +51,10 @@ public class GameState
             // TODO FIXME This is wrong for brush model entities
             uq.CurrentStyle.SetupWorldModelRenderer(mr);    // TODO FIXME this currently leaks Materials    
             
-            uint texNum = surfaceMesh.Texture.TextureNum;
+            uint texNum = surfaceMesh.TextureNum;
             if (uq.GameAssets.TryGetTexture(texNum, out var texture))
             {
-                uint fbNum = surfaceMesh.Texture.FullBrightNum;
+                uint fbNum = surfaceMesh.FullBrightNum;
                 uq.GameAssets.TryGetTexture(fbNum, out var fullBright);
                 
                 uq.CurrentStyle.SetWorldModelTextures(mr.material, texture, fullBright, null);

Assets/Scripts/Support/BrushModel.cs

@@ -159,13 +159,18 @@ public class BrushModel
     public class SurfaceMesh
     {
         public Mesh Mesh { get; }
-        public QTexture Texture { get; }
+        public uint TextureNum { get; }
+        public uint FullBrightNum { get; }
+        public uint WarpImageNum { get; }
         public int Lightmap { get; }
 
         public SurfaceMesh(Mesh mesh, IntPtr texturePtr, int lightmap)
         {
             Mesh = mesh;
-            Texture = Marshal.PtrToStructure<QTexture>(texturePtr);
+            var texture = Marshal.PtrToStructure<QTexture>(texturePtr);
+            TextureNum = texture.TextureNum;
+            FullBrightNum = texture.FullBrightNum;
+            WarpImageNum = texture.WarpImageNum;
             Lightmap = lightmap;
         }