Allow render-sorted! to use a custom sorting function

src/play_clj/core_graphics.clj

@@ -386,15 +386,23 @@ specify which layers to render with or without.
                   y (range (- (.getHeight l) 1) -1 -1)]
               {:x x :y y}))))
 
-(defn render-sorted!
+(defn ^:private sort-by-y
-  "Draws the supplied tiled-map layers and entities, sorted by latitude.
+  [entities]
+  (sort-by :y #(compare %2 %1) entities))
 
-    (render-sorted! screen [\"walls\"] entities)"
+(defn render-sorted!
-  [{:keys [^BatchTiledMapRenderer renderer
+  "Draws the supplied tiled-map layers and entities. If no sort function is
+supplied, they will be sorted by :y (latitude).
+
+    (render-sorted! screen [\"walls\"] entities)
+    (render-sorted! screen #(sort-by :x %) [\"walls\"] entities)"
+  ([screen layer-names entities]
+    (render-sorted! sort-by-y screen layer-names entities))
+  ([{:keys [^BatchTiledMapRenderer renderer
             ^Camera camera
             update-fn!]
      :as screen}
-   layer-names entities]
+    sort-fn layer-names entities]
     (doseq [ln layer-names]
       (when-not (get-in screen [:layers ln])
         (update-fn! assoc-in [[:layers ln] (split-layer screen ln)])))
@@ -403,12 +411,12 @@ specify which layers to render with or without.
       (.begin batch)
       (doseq [entity (->> (map #(get-in screen [:layers %]) layer-names)
                           (apply concat entities)
-                        (sort-by :y #(compare %2 %1)))]
+                          sort-fn)]
         (if-let [layer (:layer entity)]
           (.renderTileLayer renderer layer)
           (e/draw-entity! entity batch)))
       (.end batch))
-  entities)
+    entities))
 
 (defmacro render-shapes!
   "Draws shapes with a `shape` renderer.