BitmapMask and GeometryMask both have new destroy methods which clear their references, freeing them for gc.

CHANGELOG.md

@@ -12,7 +12,8 @@
 * If you're using Webpack with Phaser you'll need to update your config to match our new one.
 * We've swapped use of the Webpack DefinePlugin so instead of setting a global flag for the compilation of the Canvas and WebGL renderers, we now use a typeof check instead. This means you should now be able to ingest the Phaser source more easily outside of Webpack without having to define any global vars first (thanks @tgrajewski)
 * Under Webpack we still use the raw-loader to import our shader source, but outside of Webpack we now use `require.extensions` to load the shader source via fs. This should allow you to bundle Phaser with packages other than Webpack more easily (thanks @tgrajewski)
-* The Texture Manager will now emit an `addtexture` event whenever you add a new texture to it, which includes when you load images files from the Loader (as it automatically populates the Texture Manager). Once you receive an `addtexture` event you know the image is loaded and the texture is safe to be applied to a Game Object.
+* The Texture Manager will now emit an `addtexture` event whenever you add a new texture to it, which includes when you load image files from the Loader (as it automatically populates the Texture Manager). Once you receive an `addtexture` event you know the image is loaded and the texture is safe to be applied to a Game Object.
+* BitmapMask and GeometryMask both have new `destroy` methods which clear their references, freeing them for gc.
 
 ### Bug Fixes
 

src/display/mask/BitmapMask.js

@@ -191,6 +191,24 @@ var BitmapMask = new Class({
     postRenderCanvas: function ()
     {
         // NOOP
+    },
+
+    /**
+     * Destroys this BitmapMask and nulls any references it holds.
+     * 
+     * Note that if a Game Object is currently using this mask it will _not_ automatically detect you have destroyed it,
+     * so be sure to call `clearMask` on any Game Object using it, before destroying it.
+     *
+     * @method Phaser.Display.Masks.BitmapMask#destroy
+     * @since 3.6.1
+     */
+    destroy: function ()
+    {
+        this.bitmapMask = null;
+        this.mainTexture = null;
+        this.maskTexture = null;
+        this.mainFramebuffer = null;
+        this.maskFramebuffer = null;
     }
 
 });

src/display/mask/GeometryMask.js

@@ -131,6 +131,20 @@ var GeometryMask = new Class({
     postRenderCanvas: function (renderer)
     {
         renderer.currentContext.restore();
+    },
+
+    /**
+     * Destroys this GeometryMask and nulls any references it holds.
+     * 
+     * Note that if a Game Object is currently using this mask it will _not_ automatically detect you have destroyed it,
+     * so be sure to call `clearMask` on any Game Object using it, before destroying it.
+     *
+     * @method Phaser.Display.Masks.GeometryMask#destroy
+     * @since 3.6.1
+     */
+    destroy: function ()
+    {
+        this.geometryMask = null;
     }
 
 });

src/gameobjects/components/Mask.js

@@ -55,10 +55,19 @@ var Mask = {
      * @method Phaser.GameObjects.Components.Mask#clearMask
      * @since 3.6.2
      *
+     * @param {boolean} [destroyMask=false] - Destroy the mask before clearing it?
+     *
      * @return {Phaser.GameObjects.GameObject} This Game Object instance.
      */
-    clearMask: function ()
+    clearMask: function (destroyMask)
     {
+        if (destroyMask === undefined) { destroyMask = false; }
+
+        if (destroyMask)
+        {
+            this.mask.destroy();
+        }
+
         this.mask = null;
 
         return this;