Draw entities with a protocol instead of a multi-method

src/play_clj/core.clj

@@ -7,9 +7,8 @@
            [com.badlogic.gdx.assets AssetManager]
            [com.badlogic.gdx.graphics Camera Color GL20 OrthographicCamera
             PerspectiveCamera Texture VertexAttributes$Usage]
-           [com.badlogic.gdx.graphics.g2d NinePatch ParticleEffect SpriteBatch
+           [com.badlogic.gdx.graphics.g2d SpriteBatch]
-            TextureRegion]
+           [com.badlogic.gdx.graphics.g3d ModelBatch]
-           [com.badlogic.gdx.graphics.g3d Environment ModelBatch ModelInstance]
            [com.badlogic.gdx.input GestureDetector
             GestureDetector$GestureListener]
            [com.badlogic.gdx.maps MapLayer MapLayers MapProperties]
@@ -25,7 +24,8 @@
            [com.badlogic.gdx.scenes.scene2d Actor Stage]
            [com.badlogic.gdx.scenes.scene2d.utils ActorGestureListener Align
             ChangeListener ClickListener DragListener FocusListener]
-           [com.badlogic.gdx.utils Timer$Task]))
+           [com.badlogic.gdx.utils Timer$Task]
+           [play_clj.utils Entity]))
 
 (load "core_global")
 (load "core_graphics")

src/play_clj/core_graphics.clj

@@ -236,56 +236,12 @@ with the tiled map file at `path` and `unit` scale
   `(let [^Stage object# (u/get-obj ~screen :renderer)]
      (u/call! object# ~k ~@options)))
 
-; draw-entity
-
-(defmulti draw-entity!
-  "Internal use only"
-  (fn [_ entity] (:type entity)))
-
-(defmethod draw-entity! nil [_ _])
-
-(defmethod draw-entity! :texture
-  [^SpriteBatch batch {:keys [^TextureRegion object x y width height]}]
-  (let [x (float (or x 0))
-        y (float (or y 0))
-        width (float (or width (.getRegionWidth object)))
-        height (float (or height (.getRegionHeight object)))]
-    (.draw batch object x y width height)))
-
-(defmethod draw-entity! :nine-patch
-  [^SpriteBatch batch {:keys [^NinePatch object x y width height]}]
-  (let [x (float (or x 0))
-        y (float (or y 0))
-        width (float (or width (.getTotalWidth object)))
-        height (float (or height (.getTotalHeight object)))]
-    (.draw object batch x y width height)))
-
-(defmethod draw-entity! :particle-effect
-  [^SpriteBatch batch {:keys [^ParticleEffect object x y delta-time]}]
-  (let [x (float (or x 0))
-        y (float (or y 0))
-        delta-time (float (or delta-time (graphics! :get-delta-time)))]
-    (.setPosition object x y)
-    (.draw object batch delta-time)))
-
-(defmethod draw-entity! :actor
-  [^SpriteBatch batch {:keys [^Actor object] :as entity}]
-  (doseq [[k v] entity]
-    (case k
-      :x (.setX object v)
-      :y (.setY object v)
-      :width (.setWidth object v)
-      :height (.setHeight object v)
-      nil))
-  (.draw object batch 1))
-
-(defmethod draw-entity! :model
-  [{:keys [^ModelBatch renderer ^Environment attributes]}
-   {:keys [^ModelInstance object]}]
-  (.render renderer object attributes))
-
 ; draw
 
+(defn filter-entities
+  [entities]
+  (filter #(isa? (type %) Entity) entities))
+
 (defmulti draw!
   "Internal use only"
   (fn [screen _] (-> screen :renderer class)))
@@ -294,8 +250,8 @@ with the tiled map file at `path` and `unit` scale
   [{:keys [^BatchTiledMapRenderer renderer]} entities]
   (let [^SpriteBatch batch (.getSpriteBatch renderer)]
     (.begin batch)
-    (doseq [entity entities]
+    (doseq [entity (filter-entities entities)]
-      (draw-entity! batch entity))
+      (u/draw-entity! entity batch))
     (.end batch))
   entities)
 
@@ -303,16 +259,16 @@ with the tiled map file at `path` and `unit` scale
   [{:keys [^Stage renderer]} entities]
   (let [^SpriteBatch batch (.getSpriteBatch renderer)]
     (.begin batch)
-    (doseq [entity entities]
+    (doseq [entity (filter-entities entities)]
-      (draw-entity! batch entity))
+      (u/draw-entity! entity batch))
     (.end batch))
   entities)
 
 (defmethod draw! ModelBatch
   [{:keys [^ModelBatch renderer ^Camera camera] :as screen} entities]
   (.begin renderer camera)
-  (doseq [entity entities]
+  (doseq [entity (filter-entities entities)]
-    (draw-entity! screen entity))
+    (u/draw-entity! entity screen))
   (.end renderer)
   entities)
 
@@ -421,11 +377,11 @@ specify which layers to render with or without
   (let [^SpriteBatch batch (.getSpriteBatch renderer)]
     (.begin batch)
     (doseq [entity (->> (map #(get-in screen [:layers %]) layer-names)
-                        (apply concat entities)
+                        (apply concat (filter-entities entities))
                         (sort-by :y #(compare %2 %1)))]
       (if-let [layer (:layer entity)]
         (.renderTileLayer renderer layer)
-        (draw-entity! batch entity)))
+        (u/draw-entity! entity batch)))
     (.end batch))
   entities)
 

src/play_clj/utils.clj

@@ -1,8 +1,8 @@
 (ns play-clj.utils
   (:require [clojure.string :as s])
-  (:import [com.badlogic.gdx.graphics.g2d NinePatch ParticleEffect
+  (:import [com.badlogic.gdx.graphics.g2d NinePatch ParticleEffect SpriteBatch
             TextureRegion]
-           [com.badlogic.gdx.graphics.g3d ModelInstance]
+           [com.badlogic.gdx.graphics.g3d Environment ModelBatch ModelInstance]
            [com.badlogic.gdx.scenes.scene2d Actor]
            [com.badlogic.gdx.utils Array ArrayMap]))
 
@@ -172,7 +172,53 @@ new object to be created each time a field is set)
   [object k & options]
   `(call! ^ArrayMap ~object ~k ~@options))
 
-; entities
+; entity protocol/records
+
+(defprotocol Entity
+  "Internal use only"
+  (draw-entity! [this batch] "Draws the entity"))
+
+(defrecord TextureEntity [object] Entity
+  (draw-entity! [{:keys [^TextureRegion object x y width height]} batch]
+    (let [x (float (or x 0))
+          y (float (or y 0))
+          width (float (or width (.getRegionWidth object)))
+          height (float (or height (.getRegionHeight object)))]
+      (.draw ^SpriteBatch batch object x y width height))))
+
+(defrecord NinePatchEntity [object] Entity
+  (draw-entity! [{:keys [^NinePatch object x y width height]} batch]
+    (let [x (float (or x 0))
+          y (float (or y 0))
+          width (float (or width (.getTotalWidth object)))
+          height (float (or height (.getTotalHeight object)))]
+      (.draw object ^SpriteBatch batch x y width height))))
+
+(defrecord ParticleEffectEntity [object] Entity
+  (draw-entity! [{:keys [^ParticleEffect object x y delta-time]} batch]
+    (let [x (float (or x 0))
+          y (float (or y 0))
+          delta-time (float delta-time)]
+      (.setPosition object x y)
+      (.draw object ^SpriteBatch batch delta-time))))
+
+(defrecord ActorEntity [object] Entity
+  (draw-entity! [{:keys [^Actor object] :as entity} batch]
+    (doseq [[k v] entity]
+      (case k
+        :x (.setX object v)
+        :y (.setY object v)
+        :width (.setWidth object v)
+        :height (.setHeight object v)
+        nil))
+    (.draw object ^SpriteBatch batch 1)))
+
+(defrecord ModelEntity [object] Entity
+  (draw-entity! [{:keys [^ModelInstance object]}
+                 {:keys [^ModelBatch renderer ^Environment attributes]}]
+    (.render renderer object attributes)))
+
+; create-entity
 
 (defmulti create-entity
   "Internal use only"
@@ -180,20 +226,20 @@ new object to be created each time a field is set)
 
 (defmethod create-entity TextureRegion
   [obj]
-  {:type :texture :object obj})
+  (TextureEntity. obj))
 
 (defmethod create-entity NinePatch
   [obj]
-  {:type :nine-patch :object obj})
+  (NinePatchEntity. obj))
 
 (defmethod create-entity ParticleEffect
   [obj]
-  {:type :particle-effect :object obj})
+  (ParticleEffectEntity. obj))
 
 (defmethod create-entity Actor
   [obj]
-  {:type :actor :object obj})
+  (ActorEntity. obj))
 
 (defmethod create-entity ModelInstance
   [obj]
-  {:type :model :object obj})
+  (ModelEntity. obj))