Use texture windows to allow repeating textures on select faces.

This reduces polycounts and file sizes significantly, at the expense of more texture warping and less refined lighting.

ps1bsp.h

@@ -58,6 +58,7 @@ typedef struct
 {
 	unsigned short tpage;		// Texture page in PS1 VRAM (precalculated when generating the texture atlas)
 	unsigned short nextframe;	// If non-zero, the texture is animated and this points to the next texture in the sequence
+	unsigned int twin;			// Texture window for repeating textures
 } ps1bsp_texture_t;
 
 // This matches the SVECTOR data type; we can use the extra padding to store some more data.

world.c

@@ -193,6 +193,12 @@ 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;
@@ -205,7 +211,7 @@ static void world_drawFaces(const world_t *world, const ps1bsp_face_t *firstFace
     for (const ps1bsp_face_t *face = firstFace; face != NULL; face = face->nextFace)
     {
         // Early primitive buffer check
-        if (!mem_checkprim(sizeof(POLY_GT4), face->totalPrimitives))
+        if (!mem_checkprim(sizeof(POLY_GT4) + sizeof(DR_TWIN), face->totalPrimitives))
             break;
 
         world_drawface(world, face, curOT);
@@ -482,5 +488,11 @@ void world_draw(const world_t *world)
     else
         world_drawface = &world_drawface_lit;
 
+    // Make sure we set the texture window back to default after drawing the world
+    DR_TWIN *twin = (DR_TWIN*)mem_prim(sizeof(DR_TWIN));
+    setlen(twin, 1);
+    twin->code[0] = 0xe2000000;
+    addPrim(curOT, twin);
+
     world_drawFaces(world, firstFace);
 }