Added everything from chapter 4 and set up ESlint

.eslintignore

@@ -0,0 +1,2 @@
+projects
+examples

.eslintrc.js

@@ -0,0 +1,33 @@
+module.exports = {
+	"env": {
+		"browser": true,
+		"commonjs": true,
+		"es6": true
+	},
+	"extends": "eslint:recommended",
+	"globals": {
+		"Atomics": "readonly",
+		"SharedArrayBuffer": "readonly"
+	},
+	"parserOptions": {
+		"ecmaVersion": 2018
+	},
+	"rules": {
+		"indent": [
+			"error",
+			"tab"
+		],
+		"linebreak-style": [
+			"error",
+			"unix"
+		],
+		"quotes": [
+			"error",
+			"double"
+		],
+		"semi": [
+			"error",
+			"always"
+		]
+	}
+};

lib/AnimManager.js

@@ -0,0 +1,63 @@
+class Anim {
+	constructor(frames, rate) {
+		this.frames = frames;
+		this.rate = rate;
+		this.reset();
+	}
+
+	update(dt) {
+		const { rate, frames } = this;
+		if ((this.curTime += dt) > rate) {
+			this.curFrame++;
+			this.frame = frames[this.curFrame % frames.length];
+			this.curTime -= rate;
+		}
+	}
+
+	reset() {
+		this.frame = this.frames[0];
+		this.curFrame = 0;
+		this.curTime = 0;
+	}
+}
+
+class AnimManager {
+	constructor(e) { 
+		this.anims = {};
+		this.running = false;
+		this.frameSource = e.frame || e;
+		this.currrent = null;
+	}
+
+	add(name, frames, speed) {
+		this.anims[name] = new Anim(frames, speed);
+		return this.anims[name];
+	}
+
+	update(dt) { 
+		const { current, anims, frameSource } = this;
+		if (!current) {
+			return;
+		}
+		const anim = anims[current];
+		anim.update(dt);
+
+		frameSource.x = anim.frame.x;
+		frameSource.y = anim.frame.y;
+	}
+
+	play(anim) { 
+		const { current, anims } = this;
+		if (anim === current ) {
+			return;
+		}
+		this.current = anim;
+		anims[anim].reset();
+	}
+
+	stop() { 
+		this.current = null;
+	}
+}
+
+module.exports = AnimManager;

lib/Camera.js

@@ -0,0 +1,54 @@
+const Container = require("./Container");
+const math = require("./utilities/math");
+
+class Camera extends Container {
+	constructor(subject, viewport, worldSize = viewport) {
+		super();
+		this.w = viewport.w;
+		this.h = viewport.h;
+		this.worldSize = worldSize;
+		this.setSubject(subject);
+	}
+
+	setSubject(e) {
+		this.subject = e ? e.pos || e : this.pos;
+		this.offset = { x: 0, y: 0 };
+
+		// Center on the entity
+		if (e && e.w) {
+			this.offset.x += e.w / 2;
+			this.offset.y += e.h / 2;
+		}
+		if (e && e.anchor) {
+			this.offset.x -= e.anchor.x;
+			this.offset.y -= e.anchor.y;
+		}
+		this.focus();
+	}
+
+	focus() {
+		const { pos, w, h, worldSize, subject, offset } = this;
+
+		const centeredX = subject.x + offset.x - w / 2;
+		const maxX = worldSize.w - w;
+		const x = -math.clamp(centeredX, 0, maxX);
+
+		const centeredY = subject.y + offset.y - h / 2;
+		const maxY = worldSize.h - h;
+		const y = -math.clamp(centeredY, 0, maxY);
+
+		pos.x = x;
+		pos.y = y;
+	}
+
+	update(dt, t) {
+		super.update(dt, t);
+
+		if (this.subject) {
+			this.focus();
+		}
+	}
+}
+
+
+module.exports = Camera;

lib/Container.js

@@ -1,30 +1,30 @@
 class Container {
-  constructor() {
-    this.pos = { x: 0, y: 0 };
-    this.children = [];
-  }
+	constructor() {
+		this.pos = { x: 0, y: 0 };
+		this.children = [];
+	}
 
-  add(child) {
-    this.children.push(child);
-    return child;
-  }
+	add(child) {
+		this.children.push(child);
+		return child;
+	}
 
-  remove(child) {
-    this.children = this.children.filter(c => c !== child);
-    return child;
-  }
+	remove(child) {
+		this.children = this.children.filter(c => c !== child);
+		return child;
+	}
 
-  map(f) {
-    return this.children.map(f);
-  }
+	map(f) {
+		return this.children.map(f);
+	}
 
-  update(dt, t) {
-    this.children = this.children.filter(child => {
-      if (child.update) {
-        child.update(dt, t, this);
-      }
-      return child.dead ? false : true;
-    });
-  }
+	update(dt, t) {
+		this.children = this.children.filter(child => {
+			if (child.update) {
+				child.update(dt, t, this);
+			}
+			return child.dead ? false : true;
+		});
+	}
 }
 module.exports = Container;

lib/Game.js

@@ -1,40 +1,40 @@
 var Container = require("./Container"),
-    CanvasRenderer = require('./renderer/CanvasRenderer')
+	CanvasRenderer = require("./renderer/CanvasRenderer")
 ;
 
 const STEP = 1 / 60;
 const FRAME_MAX = 5 * STEP;
 
 class Game {
-    constructor(w, h, pixelated, parent = "#board") {
-        this.w = w;
-        this.h = h;
-        this.renderer = new CanvasRenderer(w, h);
-        document.querySelector(parent).appendChild(this.renderer.view);
+	constructor(w, h, pixelated, parent = "#board") {
+		this.w = w;
+		this.h = h;
+		this.renderer = new CanvasRenderer(w, h);
+		document.querySelector(parent).appendChild(this.renderer.view);
 
-        if (pixelated) {
-            this.renderer.setPixelated();
-        }
+		if (pixelated) {
+			this.renderer.setPixelated();
+		}
 
-        this.scene = new Container();
-    }
+		this.scene = new Container();
+	}
 
-    run(gameUpdate = () => { }) {
-        let dt = 0;
-        let last = 0;
-        const loop = ms => {
-            requestAnimationFrame(loop);
+	run(gameUpdate = () => { }) {
+		let dt = 0;
+		let last = 0;
+		const loop = ms => {
+			requestAnimationFrame(loop);
 
-            const t = ms / 1000;
-            dt = Math.min(t - last, FRAME_MAX);
-            last = t;
+			const t = ms / 1000;
+			dt = Math.min(t - last, FRAME_MAX);
+			last = t;
 
-            this.scene.update(dt, t);
-            gameUpdate(dt, t);
-            this.renderer.render(this.scene);
-        };
-        requestAnimationFrame(loop);
-    }
+			this.scene.update(dt, t);
+			gameUpdate(dt, t);
+			this.renderer.render(this.scene);
+		};
+		requestAnimationFrame(loop);
+	}
 }
 
 module.exports = Game;

lib/Rect.js

@@ -1,10 +1,10 @@
 class Rect {
-    constructor(w, h, style = { fill: "#333" }) {
-      this.pos = { x: 0, y: 0 };
-      this.w = w;
-      this.h = h;
-      this.style = style;
-    }
-  }
+	constructor(w, h, style = { fill: "#333" }) {
+		this.pos = { x: 0, y: 0 };
+		this.w = w;
+		this.h = h;
+		this.style = style;
+	}
+}
   
 module.exports = Rect;

lib/Sprite.js

@@ -1,10 +1,10 @@
 class Sprite {
-  constructor(texture) {
-    this.texture = texture;
-    this.pos = { x: 0, y: 0 };
-    this.anchor = { x: 0, y: 0 };
-    this.scale = { x: 1, y: 1 };
-    this.rotation = 0;
-  }
+	constructor(texture) {
+		this.texture = texture;
+		this.pos = { x: 0, y: 0 };
+		this.anchor = { x: 0, y: 0 };
+		this.scale = { x: 1, y: 1 };
+		this.rotation = 0;
+	}
 }
 module.exports = Sprite;

lib/SpriteSheetXML.js

@@ -1,39 +1,39 @@
 class SpriteSheetXML {
-    constructor(url) {
-        this.array = [];
-        this.fetchXMLtoArray(url);
-    }
+	constructor(url) {
+		this.array = [];
+		this.fetchXMLtoArray(url);
+	}
 
-    fetchXMLtoArray(url) {
-        var xhr = new XMLHttpRequest();
-        xhr.open('GET', url, false);
-        xhr.send(null);
+	fetchXMLtoArray(url) {
+		var xhr = new XMLHttpRequest();
+		xhr.open("GET", url, false);
+		xhr.send(null);
 
-        if (xhr.status === 200) {
-            var children = xhr.responseXML.children[0].children;
-            for (let index = 0; index < children.length; index++) {
-                const element = children[index];
-                this.array.push({
-                    name: element.attributes.name.nodeValue,
-                    x: element.attributes.x.nodeValue,
-                    y: element.attributes.y.nodeValue,
-                    width: element.attributes.width.nodeValue,
-                    height: element.attributes.height.nodeValue
-                });
-            }
-        } else {
-            console.error('XML file cannot be loaded!')
-        }
-    }
+		if (xhr.status === 200) {
+			var children = xhr.responseXML.children[0].children;
+			for (let index = 0; index < children.length; index++) {
+				const element = children[index];
+				this.array.push({
+					name: element.attributes.name.nodeValue,
+					x: element.attributes.x.nodeValue,
+					y: element.attributes.y.nodeValue,
+					width: element.attributes.width.nodeValue,
+					height: element.attributes.height.nodeValue
+				});
+			}
+		} else {
+			console.error("XML file cannot be loaded!");
+		}
+	}
 
-    findIndex(attribute, value) {
-        for (let index = 0; index < this.array.length; index++) {
-            const element = this.array[index];
-            if (element[attribute] == value) {
-                return index;
-            }
-        }
-    }
+	findIndex(attribute, value) {
+		for (let index = 0; index < this.array.length; index++) {
+			const element = this.array[index];
+			if (element[attribute] == value) {
+				return index;
+			}
+		}
+	}
 }
 
 module.exports = SpriteSheetXML;

lib/Text.js

@@ -1,8 +1,8 @@
 class Text {
-  constructor(text = "", style = {}) {
-    this.pos = { x: 0, y: 0 };
-    this.text = text;
-    this.style = style;
-  }
+	constructor(text = "", style = {}) {
+		this.pos = { x: 0, y: 0 };
+		this.text = text;
+		this.style = style;
+	}
 }
 module.exports = Text;

lib/Texture.js

@@ -1,7 +1,7 @@
 class Texture {
-  constructor(url) {
-    this.img = new Image();
-    this.img.src = url;
-  }
+	constructor(url) {
+		this.img = new Image();
+		this.img.src = url;
+	}
 }
 module.exports = Texture;

lib/TileMap.js

@@ -1,25 +1,59 @@
 var Container = require("./Container"),
-    TileSprite = require("./TileSprite")
+	TileSprite = require("./TileSprite")
 ;
 
 class TileMap extends Container {
-  constructor(tiles, mapW, mapH, tileW, tileH, texture) {
-    super();
-    this.mapW = mapW;
-    this.mapH = mapH;
-    this.tileW = tileW;
-    this.tileH = tileH;
-    this.w = mapW * tileW;
-    this.h = mapH * tileH;
+	constructor(tiles, mapW, mapH, tileW, tileH, texture) {
+		super();
+		this.mapW = mapW;
+		this.mapH = mapH;
+		this.tileW = tileW;
+		this.tileH = tileH;
+		this.w = mapW * tileW;
+		this.h = mapH * tileH;
 
-    this.children = tiles.map((frame, i) => {
-      const s = new TileSprite(texture, tileW, tileH);
-      s.frame = frame;
-      s.pos.x = i % mapW * tileW;
-      s.pos.y = Math.floor(i / mapW) * tileH;
-      return s;
-    });
-  }
+		this.children = tiles.map((frame, i) => {
+			const s = new TileSprite(texture, tileW, tileH);
+			s.frame = frame;
+			s.pos.x = i % mapW * tileW;
+			s.pos.y = Math.floor(i / mapW) * tileH;
+			return s;
+		});
+	}
+
+	pixelToMapPos(pos) {
+		const { tileW, tileH } = this;
+		return {
+			x: Math.floor(pos.x / tileW),
+			y: Math.floor(pos.y / tileH)
+		};
+	}
+
+	mapToPixelPos(mapPos) {
+		const { tileW, tileH } = this;
+		return {
+			x: mapPos.x * tileW,
+			y: mapPos.y * tileH
+		};
+	}
+
+	tileAtMapPos(mapPos) {
+		return this.children[mapPos.y * this.mapW + mapPos.x];
+	}
+
+	tileAtPixelPos(pos) {
+		return this.tileAtMapPos(this.pixelToMapPos(pos));
+	}
+
+	setFrameAtMapPos(mapPos, frame) {
+		const tile = this.tileAtMapPos(mapPos);
+		tile.frame = frame;
+		return tile;
+	}
+
+	setFrameAtPixelPos(pos, frame) {
+		return this.setFrameAtMapPos(this.pixelToMapPos(pos), frame);
+	}
 }
 
 module.exports = TileMap;

lib/TileMapXML.js

@@ -1,25 +1,25 @@
 var Container = require("./Container"),
-    TileSpriteXML = require("./TileSpriteXML")
+	TileSpriteXML = require("./TileSpriteXML")
 ;
 
 class TileMapXML extends Container {
-    constructor(tiles, mapW, mapH, texture, xml) {
-        super(texture);
-        this.mapW = mapW;
-        this.mapH = mapH;
-        this.tileW = xml.array[tiles[0]].width;
-        this.tileH = xml.array[tiles[0]].height;
-        this.w = mapW * this.tileW;
-        this.h = mapH * this.tileH;
+	constructor(tiles, mapW, mapH, texture, xml) {
+		super(texture);
+		this.mapW = mapW;
+		this.mapH = mapH;
+		this.tileW = xml.array[tiles[0]].width;
+		this.tileH = xml.array[tiles[0]].height;
+		this.w = mapW * this.tileW;
+		this.h = mapH * this.tileH;
         
-        this.children = tiles.map((frame, i) => {
-            const s = new TileSpriteXML(texture, xml, frame);
-            s.frame = frame;
-            s.pos.x = i % mapW * this.tileW;
-            s.pos.y = Math.floor(i / mapW) * this.tileH;
-            return s;
-        });
-    }
+		this.children = tiles.map((frame, i) => {
+			const s = new TileSpriteXML(texture, xml, frame);
+			s.frame = frame;
+			s.pos.x = i % mapW * this.tileW;
+			s.pos.y = Math.floor(i / mapW) * this.tileH;
+			return s;
+		});
+	}
 }
 
 module.exports = TileMapXML;

lib/TileSprite.js

@@ -1,12 +1,12 @@
 var Sprite = require("./Sprite");
 
 class TileSprite extends Sprite {
-    constructor(texture, w, h) {
-        super(texture);
-        this.tileW = w;
-        this.tileH = h;
-        this.frame = { x: 0, y: 0 };
-    }
+	constructor(texture, w, h) {
+		super(texture);
+		this.tileW = w;
+		this.tileH = h;
+		this.frame = { x: 0, y: 0 };
+	}
 }
 
 module.exports = TileSprite;

lib/TileSpriteXML.js

@@ -1,13 +1,13 @@
 var Sprite = require("./Sprite");
 
 class TileSpriteXML extends Sprite {
-    constructor(texture, xml, index) {
-        super(texture);
-        var src = xml.array[index];
-        this.imgPos = { x: src['x'], y: src['y'] };
-        this.width = src['width'];
-        this.height = src['height'];
-    }
+	constructor(texture, xml, index) {
+		super(texture);
+		var src = xml.array[index];
+		this.imgPos = { x: src["x"], y: src["y"] };
+		this.width = src["width"];
+		this.height = src["height"];
+	}
 }
 
 module.exports = TileSpriteXML;

lib/controls/KeyControls.js

@@ -1,61 +1,61 @@
 class KeyControls {
   
-  constructor() {
-    this.keys = {};
-    // Bind event handlers
-    document.addEventListener("keydown", e => {
-      if ([37, 38, 39, 40].indexOf(e.which) >= 0) {
-        e.preventDefault();
-      }
-      this.keys[e.which] = true;
-    }, false);
-    document.addEventListener('keyup', e => {
-      this.keys[e.which] = false;
-    }, false);
-  }
+	constructor() {
+		this.keys = {};
+		// Bind event handlers
+		document.addEventListener("keydown", e => {
+			if ([37, 38, 39, 40].indexOf(e.which) >= 0) {
+				e.preventDefault();
+			}
+			this.keys[e.which] = true;
+		}, false);
+		document.addEventListener("keyup", e => {
+			this.keys[e.which] = false;
+		}, false);
+	}
 
-  get action() {
-    // Spacebar
-    return this.keys[32];
-  }
+	get action() {
+		// Spacebar
+		return this.keys[32];
+	}
 
-  get x() {
-    // Arrow Left or A (WASD)
-    if (this.keys[37] || this.keys[65]) {
-      return -1;
-    }
-    // Arrow Right or D (WASD)
-    if (this.keys[39] || this.keys[68]) {
-      return 1;
-    }
-    return 0;
-  }
+	get x() {
+		// Arrow Left or A (WASD)
+		if (this.keys[37] || this.keys[65]) {
+			return -1;
+		}
+		// Arrow Right or D (WASD)
+		if (this.keys[39] || this.keys[68]) {
+			return 1;
+		}
+		return 0;
+	}
 
-  get y() {
-    // Arrow Up or W (WASD)
-    if (this.keys[38] || this.keys[87]) {
-      return -1;
-    }
-    // Arrow Down or S (WASD)
-    if (this.keys[40] || this.keys[83]) {
-      return 1;
-    }
-    return 0;
-  }
+	get y() {
+		// Arrow Up or W (WASD)
+		if (this.keys[38] || this.keys[87]) {
+			return -1;
+		}
+		// Arrow Down or S (WASD)
+		if (this.keys[40] || this.keys[83]) {
+			return 1;
+		}
+		return 0;
+	}
 
   
-  key(key, value) {
-    if (value !== undefined) {
-      this.keys[key] = value;
-    }
-    return this.keys[key];
-  }
+	key(key, value) {
+		if (value !== undefined) {
+			this.keys[key] = value;
+		}
+		return this.keys[key];
+	}
 
-  reset() {
-    for (let key in this.keys) {
-      this.keys[key] = false;
-    }
-  }
+	reset() {
+		for (let key in this.keys) {
+			this.keys[key] = false;
+		}
+	}
 
 }
 

lib/controls/MouseControls.js

@@ -1,45 +1,45 @@
 class MouseControls {
-  constructor(container) {
-    this.el = container || document.body;
-    // State
-    this.pos = { x: 0, y: 0 };
-    this.isDown = false;
-    this.pressed = false;
-    this.released = false;
-    // Handlers
-    document.addEventListener('mousemove', this.move.bind(this), false);
-    document.addEventListener('mousedown', this.down.bind(this), false);
-    document.addEventListener('mouseup', this.up.bind(this), false);
-  }
+	constructor(container) {
+		this.el = container || document.body;
+		// State
+		this.pos = { x: 0, y: 0 };
+		this.isDown = false;
+		this.pressed = false;
+		this.released = false;
+		// Handlers
+		document.addEventListener("mousemove", this.move.bind(this), false);
+		document.addEventListener("mousedown", this.down.bind(this), false);
+		document.addEventListener("mouseup", this.up.bind(this), false);
+	}
 
-  mousePosFromEvent({ clientX, clientY }) {
-    const { el, pos } = this;
-    const rect = el.getBoundingClientRect();
-    const xr = el.width / el.clientWidth;
-    const yr = el.height / el.clientHeight;
-    pos.x = (clientX - rect.left) * xr;
-    pos.y = (clientY - rect.top) * yr;
-  }
+	mousePosFromEvent({ clientX, clientY }) {
+		const { el, pos } = this;
+		const rect = el.getBoundingClientRect();
+		const xr = el.width / el.clientWidth;
+		const yr = el.height / el.clientHeight;
+		pos.x = (clientX - rect.left) * xr;
+		pos.y = (clientY - rect.top) * yr;
+	}
 
-  move(e) {
-    this.mousePosFromEvent(e);
-  }
+	move(e) {
+		this.mousePosFromEvent(e);
+	}
 
-  down(e) {
-    this.isDown = true;
-    this.pressed = true;
-    this.mousePosFromEvent(e);
-  }
+	down(e) {
+		this.isDown = true;
+		this.pressed = true;
+		this.mousePosFromEvent(e);
+	}
 
-  up() {
-    this.isDown = false;
-    this.released = true;
-  }
+	up() {
+		this.isDown = false;
+		this.released = true;
+	}
 
-  update() {
-    this.released = false;
-    this.pressed = false;
-  }
+	update() {
+		this.released = false;
+		this.pressed = false;
+	}
 }
 
 module.exports = MouseControls;

lib/index.js

@@ -1,36 +1,40 @@
-var Container = require("./Container.js"),
-    CanvasRenderer = require("./renderer/CanvasRenderer.js"),
-    Game = require("./Game.js"),
-    math = require("./utilities/math.js"),
-    entity = require("./utilities/entity.js"),
-    Rect = require("./Rect.js"),
-    KeyControls = require("./controls/KeyControls.js"),
-    MouseControls = require("./controls/MouseControls.js"),
-    Sprite = require("./Sprite.js"),
-    TileMap = require("./TileMap.js"),
-    TileMapXML = require("./TileMapXML.js"),
-    TileSprite = require("./TileSprite.js"),
-    TileSpriteXML = require("./TileSpriteXML.js"),
-    Text = require("./Text.js"),
-    Texture = require("./Texture.js"),
-    SpriteSheetXML = require("./SpriteSheetXML.js")
+var AnimManager = require("./AnimManager.js"),
+	Camera = require("./Camera.js"),
+	Container = require("./Container.js"),
+	CanvasRenderer = require("./renderer/CanvasRenderer.js"),
+	Game = require("./Game.js"),
+	math = require("./utilities/math.js"),
+	entity = require("./utilities/entity.js"),
+	Rect = require("./Rect.js"),
+	KeyControls = require("./controls/KeyControls.js"),
+	MouseControls = require("./controls/MouseControls.js"),
+	Sprite = require("./Sprite.js"),
+	TileMap = require("./TileMap.js"),
+	TileMapXML = require("./TileMapXML.js"),
+	TileSprite = require("./TileSprite.js"),
+	TileSpriteXML = require("./TileSpriteXML.js"),
+	Text = require("./Text.js"),
+	Texture = require("./Texture.js"),
+	SpriteSheetXML = require("./SpriteSheetXML.js")
 ;
 
 module.exports = {
-  CanvasRenderer,
-  Container,
-  Game,
-  math,
-  entity,
-  Rect,
-  KeyControls,
-  MouseControls,
-  Sprite,
-  TileMap,
-  TileMapXML,
-  TileSprite,
-  SpriteSheetXML,
-  TileSpriteXML,
-  Text,
-  Texture
+	AnimManager,
+	CanvasRenderer,
+	Camera,
+	Container,
+	Game,
+	math,
+	entity,
+	Rect,
+	KeyControls,
+	MouseControls,
+	Sprite,
+	TileMap,
+	TileMapXML,
+	TileSprite,
+	SpriteSheetXML,
+	TileSpriteXML,
+	Text,
+	Texture
 };

lib/renderer/CanvasRenderer.js

@@ -1,100 +1,100 @@
 class CanvasRenderer {
   
-  constructor(w, h) {
-    const canvas = document.createElement("canvas");
-    this.w = canvas.width = w;
-    this.h = canvas.height = h;
-    this.view = canvas;
-    this.ctx = canvas.getContext("2d");
-    this.ctx.textBaseLine = "top";
-  }
+	constructor(w, h) {
+		const canvas = document.createElement("canvas");
+		this.w = canvas.width = w;
+		this.h = canvas.height = h;
+		this.view = canvas;
+		this.ctx = canvas.getContext("2d");
+		this.ctx.textBaseLine = "top";
+	}
 
-  setPixelated() {
-    this.ctx['imageSmoothingEnabled'] = false;       /* standard */
-    this.ctx['mozImageSmoothingEnabled'] = false;    /* Firefox */
-    this.ctx['oImageSmoothingEnabled'] = false;      /* Opera */
-    this.ctx['webkitImageSmoothingEnabled'] = false; /* Safari */
-    this.ctx['msImageSmoothingEnabled'] = false;     /* IE */
-  }
+	setPixelated() {
+		this.ctx["imageSmoothingEnabled"] = false;       /* standard */
+		this.ctx["mozImageSmoothingEnabled"] = false;    /* Firefox */
+		this.ctx["oImageSmoothingEnabled"] = false;      /* Opera */
+		this.ctx["webkitImageSmoothingEnabled"] = false; /* Safari */
+		this.ctx["msImageSmoothingEnabled"] = false;     /* IE */
+	}
 
-  render(container, clear = true) {
-    const { ctx } = this;
-    function renderRec(container) {
-      // Render container children
-      container.children.forEach(child => {
-        if (child.visible == false) {
-          return;
-        }
+	render(container, clear = true) {
+		const { ctx } = this;
+		function renderRec(container) {
+			// Render container children
+			container.children.forEach(child => {
+				if (child.visible == false) {
+					return;
+				}
 
-        ctx.save();
+				ctx.save();
 
-        if (child.pos) {
-          ctx.translate(Math.round(child.pos.x), Math.round(child.pos.y));
-        }
+				if (child.pos) {
+					ctx.translate(Math.round(child.pos.x), Math.round(child.pos.y));
+				}
 
-        if (child.anchor) {
-          ctx.translate(child.anchor.x, child.anchor.y);
-        }
+				if (child.anchor) {
+					ctx.translate(child.anchor.x, child.anchor.y);
+				}
 
-        if (child.scale) {
-          ctx.scale(child.scale.x, child.scale.y);
-        }
+				if (child.scale) {
+					ctx.scale(child.scale.x, child.scale.y);
+				}
 
-        if (child.rotation) {
-          const px = child.pivot ? child.pivot.x : 0;
-          const py = child.pivot ? child.pivot.y : 0;
-          ctx.translate(px, py);
-          ctx.rotate(child.rotation);
-          ctx.translate(-px, -py);
-        }
+				if (child.rotation) {
+					const px = child.pivot ? child.pivot.x : 0;
+					const py = child.pivot ? child.pivot.y : 0;
+					ctx.translate(px, py);
+					ctx.rotate(child.rotation);
+					ctx.translate(-px, -py);
+				}
 
-        if (child.text) {
-          const { font, fill, align } = child.style;
-          if (font) ctx.font = font;
-          if (fill) ctx.fillStyle = fill;
-          if (align) ctx.textAlign = align;
-          ctx.fillText(child.text, 0, 0);
-        }
+				if (child.text) {
+					const { font, fill, align } = child.style;
+					if (font) ctx.font = font;
+					if (fill) ctx.fillStyle = fill;
+					if (align) ctx.textAlign = align;
+					ctx.fillText(child.text, 0, 0);
+				}
 
-        else if (child.texture) {
-          const img = child.texture.img;
-          if (child.tileW && child.tileH) {
-            ctx.drawImage(
-              img,
-              child.frame.x * child.tileW,
-              child.frame.y * child.tileH,
-              child.tileW, child.tileH,
-              0, 0,
-              child.tileW, child.tileH
-            );
-          } else if (child.imgPos && child.width && child.height) {
-            ctx.drawImage(
-              img,
-              child.imgPos.x,
-              child.imgPos.y,
-              child.width, child.height,
-              0, 0,
-              child.width, child.height
-            );
-          } else if (child.style && child.w && child.h) { 
-            ctx.fillStyle = child.style.fill; 
-            ctx.fillRect(0, 0, child.w, child.h)
-          } else {
-            ctx.drawImage(img, 0, 0);
-          }
-        }
+				else if (child.texture) {
+					const img = child.texture.img;
+					if (child.tileW && child.tileH) {
+						ctx.drawImage(
+							img,
+							child.frame.x * child.tileW,
+							child.frame.y * child.tileH,
+							child.tileW, child.tileH,
+							0, 0,
+							child.tileW, child.tileH
+						);
+					} else if (child.imgPos && child.width && child.height) {
+						ctx.drawImage(
+							img,
+							child.imgPos.x,
+							child.imgPos.y,
+							child.width, child.height,
+							0, 0,
+							child.width, child.height
+						);
+					} else if (child.style && child.w && child.h) { 
+						ctx.fillStyle = child.style.fill; 
+						ctx.fillRect(0, 0, child.w, child.h);
+					} else {
+						ctx.drawImage(img, 0, 0);
+					}
+				}
 
-        // Handle children with children
-        if (child.children) {
-          renderRec(child);
-        }
-        ctx.restore();
-      })
-    }
-    if (clear) {
-      ctx.clearRect(0, 0, this.w, this.h);
-    }
-    renderRec(container);
-  }
+				// Handle children with children
+				if (child.children) {
+					renderRec(child);
+				}
+				ctx.restore();
+			});
+		}
+		if (clear) {
+			ctx.clearRect(0, 0, this.w, this.h);
+		}
+		renderRec(container);
+	}
 }
 module.exports = CanvasRenderer;

lib/utilities/entity.js

@@ -1,79 +1,79 @@
-const math = require('./math');
-const Rect = require('../Rect');
+const math = require("./math");
+const Rect = require("../Rect");
 
 function addDebug(e) {
-  e.children = e.children || [];
-  const bb = new Rect(e.w, e.h, { fill: "rgba(255, 0, 0, 0.3)" });
-  e.children.push(bb);
-  if (e.hitBox) {
-    const { x, y, w, h } = e.hitBox;
-    const hb = new Rect(w, h, { fill: "rgba(255, 0, 0, 0.5)" });
-    hb.pos.x = x;
-    hb.pos.y = y;
-    e.children.push(hb);
-  }
-  return e;
+	e.children = e.children || [];
+	const bb = new Rect(e.w, e.h, { fill: "rgba(255, 0, 0, 0.3)" });
+	e.children.push(bb);
+	if (e.hitBox) {
+		const { x, y, w, h } = e.hitBox;
+		const hb = new Rect(w, h, { fill: "rgba(255, 0, 0, 0.5)" });
+		hb.pos.x = x;
+		hb.pos.y = y;
+		e.children.push(hb);
+	}
+	return e;
 }
 
 function angle(a, b) {
-  return math.angle(center(a), center(b));
+	return math.angle(center(a), center(b));
 }
 
 function bounds(entity) {
-  const { w, h, pos, hitBox } = entity;
-  const hit = hitBox || { x: 0, y: 0, w, h };
-  return {
-    x: hit.x + pos.x,
-    y: hit.y + pos.y,
-    w: hit.w - 1,
-    h: hit.h - 1
-  };
+	const { w, h, pos, hitBox } = entity;
+	const hit = hitBox || { x: 0, y: 0, w, h };
+	return {
+		x: hit.x + pos.x,
+		y: hit.y + pos.y,
+		w: hit.w - 1,
+		h: hit.h - 1
+	};
 }
 
 function center(entity) {
-  const { pos, w, h } = entity;
-  return {
-    x: pos.x + w / 2,
-    y: pos.y + h / 2
-  };
+	const { pos, w, h } = entity;
+	return {
+		x: pos.x + w / 2,
+		y: pos.y + h / 2
+	};
 }
 
 function distance(a, b) {
-  return math.distance(center(a), center(b));
+	return math.distance(center(a), center(b));
 }
 
 function hit(e1, e2) {
-  const a = bounds(e1);
-  const b = bounds(e2);
-  return (
-    a.x + a.w >= b.x &&
+	const a = bounds(e1);
+	const b = bounds(e2);
+	return (
+		a.x + a.w >= b.x &&
     a.x <= b.x + b.w &&
     a.y + a.h >= b.y &&
     a.y <= b.y + b.h
-  );
+	);
 }
 
 function hits(entity, container, hitCallback) {
-  const a = bounds(entity);
-  container.map(e2 => {
-    const b = bounds(e2);
-    if (
-      a.x + a.w >= b.x &&
+	const a = bounds(entity);
+	container.map(e2 => {
+		const b = bounds(e2);
+		if (
+			a.x + a.w >= b.x &&
       a.x <= b.x + b.w &&
       a.y + a.h >= b.y &&
       a.y <= b.y + b.h
-    ) {
-      hitCallback(e2);
-    }
-  });
+		) {
+			hitCallback(e2);
+		}
+	});
 }
 
 module.exports = {
-  addDebug,
-  angle,
-  bounds,
-  center,
-  distance,
-  hit,
-  hits
+	addDebug,
+	angle,
+	bounds,
+	center,
+	distance,
+	hit,
+	hits
 };

lib/utilities/math.js

@@ -1,26 +1,48 @@
+function angle(a, b) {
+	const dx = a.x - b.x;
+	const dy = a.y - b.y;
+	const angle = Math.atan2(dy, dx);
+
+	return angle;
+}
+
+function clamp(x, min, max) {
+	return Math.max(min, Math.min(x, max));
+}
+
+function distance (a, b) {
+	const dx = a.x - b.x;
+	const dy = a.y - b.y;
+
+	return Math.sqrt(dx * dx + dy * dy);
+}
+
 function rand(min, max) {
-  return Math.floor(randf(min, max));
+	return Math.floor(randf(min, max));
 }
 
 function randf(min, max) {
-  if (max == null) {
-    max = min || 1;
-    min = 0;
-  }
-  return Math.random() * (max - min) + min;
+	if (max == null) {
+		max = min || 1;
+		min = 0;
+	}
+	return Math.random() * (max - min) + min;
 }
 
 function randOneFrom(items) {
-  return items[rand(items.length)];
+	return items[rand(items.length)];
 }
 
 function randOneIn(max = 2) {
-  return rand(0, max) === 0;
+	return rand(0, max) === 0;
 }
 
 module.exports = {
-  rand,
-  randf,
-  randOneFrom,
-  randOneIn
+	angle,
+	clamp,
+	distance,
+	rand,
+	randf,
+	randOneFrom,
+	randOneIn
 };

package.json

@@ -17,5 +17,8 @@
     "name": "Arne van Iterson",
     "url": "https://gitea.arnweb.nl/arne/"
   },
-  "license": "ISC"
+  "license": "ISC",
+  "devDependencies": {
+    "eslint": "^6.8.0"
+  }
 }