twn_textures.c: fix srcrect setting on atlas rebuild

src/twn_textures.c

@@ -130,8 +130,8 @@ static void upload_texture_from_surface(gpu_texture texture, SDL_Surface *surfac
 
 
 static void recreate_current_atlas_texture(struct texture_cache *cache) {
-    /* TODO: figure out if SDL_UpdateTexture alone is faster than blitting */
     /* TODO: should surfaces be freed after they cannot be referenced in atlas builing? */
+    /*       for example, if full page of 64x64 tiles was already filled, there's no real reason to process them further */
     SDL_Surface *atlas_surface = cache->atlas_surfaces[cache->atlas_index];
 
     /* clear */
@@ -230,13 +230,19 @@ static bool update_rects(struct texture_cache *cache, stbrp_rect *rects, stbrp_r
 
 /* updates the atlas location of every rect in the cache */
 static void update_texture_rects_in_atlas(struct texture_cache *cache, stbrp_rect *rects) {
+    int r = 0;
     for (size_t i = 0; i < arrlenu(rects); ++i) {
+        if (cache->hash[i].value.loner_texture != 0)
+            continue;
+
         cache->hash[i].value.srcrect = (t_frect) {
-            .x = (float)rects[i].x,
-            .y = (float)rects[i].y,
-            .w = (float)rects[i].w,
-            .h = (float)rects[i].h,
+            .x = (float)rects[r].x,
+            .y = (float)rects[r].y,
+            .w = (float)rects[r].w,
+            .h = (float)rects[r].h,
         };
+
+        r++;
     }
 }