Sync with published result of Episode 3.

public/js/Timer.js

@@ -1,5 +1,5 @@
 export default class Timer {
-    constructor(deltaTime) {
+    constructor(deltaTime = 1/60) {
         let accumulatedTime = 0;
         let lastTime = 0;
 
@@ -13,10 +13,8 @@ export default class Timer {
 
             lastTime = time;
 
-            this.draw();
-
             this.enqueue();
-        };
+        }
     }
 
     enqueue() {

public/js/entities.js

@@ -3,11 +3,11 @@ import {loadMarioSprite} from './sprites.js';
 
 export function createMario() {
     return loadMarioSprite()
-    .then(marioSprite => {
+    .then(sprite => {
         const mario = new Entity();
 
         mario.draw = function drawMario(context) {
-            marioSprite.draw('idle', context, this.pos.x, this.pos.y);
+            sprite.draw('idle', context, this.pos.x, this.pos.y);
         }
 
         mario.update = function updateMario(deltaTime) {
@@ -17,4 +17,4 @@ export function createMario() {
 
         return mario;
     });
-}
+}

public/js/layers.js

@@ -22,10 +22,8 @@ export function createBackgroundLayer(backgrounds, sprites) {
     };
 }
 
-export function createSpriteLayer(entities) {
+export function createSpriteLayer(entity) {
     return function drawSpriteLayer(context) {
-        entities.forEach(entity => {
-            entity.draw(context);
-        });
+        entity.draw(context);
     };
 }

public/js/main.js

@@ -1,15 +1,13 @@
 import Compositor from './Compositor.js';
-import Entity from './Entity.js';
 import Timer from './Timer.js';
-import {createMario} from './entities.js';
 import {loadLevel} from './loaders.js';
-import {loadMarioSprite, loadBackgroundSprites} from './sprites.js';
+import {createMario} from './entities.js';
+import {loadBackgroundSprites} from './sprites.js';
 import {createBackgroundLayer, createSpriteLayer} from './layers.js';
 
 const canvas = document.getElementById('screen');
 const context = canvas.getContext('2d');
 
-
 Promise.all([
     createMario(),
     loadBackgroundSprites(),
@@ -21,26 +19,20 @@ Promise.all([
     const backgroundLayer = createBackgroundLayer(level.backgrounds, backgroundSprites);
     comp.layers.push(backgroundLayer);
 
-    mario.pos.x = 64;
-    mario.pos.y = 180;
-    mario.vel.x = 200;
-    mario.vel.y = -600;
+    const gravity = 30;
+    mario.pos.set(64, 180);
+    mario.vel.set(200, -600);
 
-    const entities = [mario];
 
-    const spriteLayer = createSpriteLayer(entities);
+    const spriteLayer = createSpriteLayer(mario);
     comp.layers.push(spriteLayer);
 
     const timer = new Timer(1/60);
     timer.update = function update(deltaTime) {
-        entities.forEach(entity => {
-            entity.update(deltaTime);
-            entity.vel.y += 30;
-        });
-    };
-    timer.draw = function draw() {
         comp.draw(context);
-    };
+        mario.update(deltaTime);
+        mario.vel.y += gravity;
+    }
 
     timer.start();
 });

public/js/math.js

@@ -1,5 +1,9 @@
 export class Vec2 {
     constructor(x, y) {
+        this.set(x, y);
+    }
+
+    set(x, y) {
         this.x = x;
         this.y = y;
     }