Add global asset manager

src/play_clj/core.clj

@@ -8,10 +8,11 @@
            [com.badlogic.gdx.audio Sound]
            [com.badlogic.gdx.assets AssetManager]
            [com.badlogic.gdx.assets.loaders AsynchronousAssetLoader]
+           [com.badlogic.gdx.files FileHandle]
            [com.badlogic.gdx.graphics Camera Color GL20 OrthographicCamera
             PerspectiveCamera Pixmap Pixmap$Format PixmapIO Texture
             VertexAttributes$Usage]
-           [com.badlogic.gdx.graphics.g2d SpriteBatch]
+           [com.badlogic.gdx.graphics.g2d ParticleEffect SpriteBatch]
            [com.badlogic.gdx.graphics.g3d ModelBatch]
            [com.badlogic.gdx.graphics.glutils ShapeRenderer]
            [com.badlogic.gdx.input GestureDetector
@@ -165,6 +166,20 @@ handle errors and perform other custom actions each time they run.
   [wrapper-fn]
   (intern 'play-clj.core 'wrapper wrapper-fn))
 
+(defn set-asset-manager!
+  "Sets a global asset manager, which will keep track of objects that need to
+be manually disposed, such as `texture` entities and `pixmap` objects. The
+asset manager will then allow you to dispose them all at once.
+
+    ; create an asset manager
+    (def manager (asset-manager))
+    ; set it to be used by play-clj
+    (set-asset-manager! manager)
+    ; dispose all assets at once
+    (asset-manager! manager :clear)"
+  [am]
+  (intern 'play-clj.utils '*asset-manager* am))
+
 (defn update!
   "Runs the equivalent of `(swap! screen-atom assoc ...)`, where `screen-atom`
 is the atom storing the screen map behind the scenes. Returns the updated