Step 7.25: Delete shape instances in game

Author: DAB0mB

resources/scripts/engine/game.js

@@ -95,6 +95,7 @@ Engine.Game = class Game {
   changeScreen(Screen, ...screenArgs) {
     // If there is a screen defined, dispose it first
     if (this.screen) {
+      this.screen.delete();
       this.unloadScreen();
       this.screen.disposeEventListeners();
     }

resources/scripts/engine/layer.js

@@ -23,6 +23,9 @@ Engine.Layer = class Layer {
     this.canvas = screen.game.canvas;
   }
 
+  delete() {
+  }
+
   update(span) {
   }
 

resources/scripts/engine/screen.js

@@ -28,6 +28,13 @@ Engine.Screen = class Screen {
     return this;
   }
 
+   // Delete all layers. Same as 'unload', only it disposes memory rather than assets
+  delete() {
+    this.layers.forEach(layer => {
+      layer.delete();
+    });
+  }
+
   // Updates each layer
   update(span) {
     this.layers.forEach(layer => {
@@ -61,6 +68,7 @@ Engine.Screen = class Screen {
   removeLayer(layer) {
     this.layers = _.without(this.layers, layer);
     layer.disposeEventListeners();
+    layer.delete();
   }
 
   initEventListeners() {

resources/scripts/game/entities/snake.js

@@ -31,6 +31,10 @@ Game.Entities.Snake = class Snake {
     }
   }
 
+  delete() {
+    this.shapes.forEach(shape => shape.delete());
+  }
+
   draw(context) {
     // Draw all shapes in the shapes array
     this.shapes.forEach(shape => {
@@ -229,6 +233,8 @@ Game.Entities.Snake = class Snake {
       [0, height, 0, 0]
     );
 
-    return canvasPolygon.getIntersection(this.lastBit);
+    let result = canvasPolygon.getIntersection(this.lastBit);
+    canvasPolygon.delete();
+    return result;
   }
 };

resources/scripts/game/screens/play/snake.js

@@ -43,6 +43,10 @@ Game.Screens.Play.Snake = class Snake extends Engine.Layer {
     screen.appendLayer(Game.Screens.Play.Score, this.snakes);
   }
 
+  unload() {
+    this.snakes.forEach(snake => snake.delete());
+  }
+
   draw(context) {
     // Draw each snake in the snakes array
     this.snakes.forEach(snake => snake.draw(context));