Swap texture window only when the texture changes between faces.

Saves a bit on performance, though could be even better if we checked for texture window changes instead of texture ID.

world.c

@@ -193,12 +193,6 @@ static void world_drawface_textured(const world_t *world, const ps1bsp_face_t *f
             }
         }
     }
-
-    // Texture window commands needs to be placed *after* the draw commands, because the commands are executed in reverse order
-    DR_TWIN *twin = (DR_TWIN*)mem_prim(sizeof(DR_TWIN));
-    setlen(twin, 1);
-    twin->code[0] = texture->twin;
-    addPrim(ot, twin);
 }
 
 static void (*world_drawface)(const world_t*, const ps1bsp_face_t*, u_long *ot) = &world_drawface_fast;
@@ -215,6 +209,16 @@ static void world_drawFaces(const world_t *world, const ps1bsp_face_t *firstFace
             break;
 
         world_drawface(world, face, curOT);
+
+        // Texture window commands needs to be placed *after* the draw commands, because the commands are executed in reverse order
+        if (face->nextFace == NULL || face->textureId != face->nextFace->textureId)
+        {
+            const ps1bsp_texture_t *texture = &world->textures[face->textureId];
+            DR_TWIN *twin = (DR_TWIN*)mem_prim(sizeof(DR_TWIN));
+            setlen(twin, 1);
+            twin->code[0] = texture->twin;
+            addPrim(curOT, twin);
+        }
     }
 }