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/Game.js

@@ -1,5 +1,5 @@
 var Container = require("./Container"),
-    CanvasRenderer = require('./renderer/CanvasRenderer')
+	CanvasRenderer = require("./renderer/CanvasRenderer")
 ;
 
 const STEP = 1 / 60;

lib/SpriteSheetXML.js

@@ -6,7 +6,7 @@ class SpriteSheetXML {
 
 	fetchXMLtoArray(url) {
 		var xhr = new XMLHttpRequest();
-        xhr.open('GET', url, false);
+		xhr.open("GET", url, false);
 		xhr.send(null);
 
 		if (xhr.status === 200) {
@@ -22,7 +22,7 @@ class SpriteSheetXML {
 				});
 			}
 		} else {
-            console.error('XML file cannot be loaded!')
+			console.error("XML file cannot be loaded!");
 		}
 	}
 

lib/TileMap.js

@@ -20,6 +20,40 @@ class TileMap extends Container {
 			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/TileSpriteXML.js

@@ -4,9 +4,9 @@ class TileSpriteXML extends Sprite {
 	constructor(texture, xml, index) {
 		super(texture);
 		var src = xml.array[index];
-        this.imgPos = { x: src['x'], y: src['y'] };
+		this.imgPos = { x: src["x"], y: src["y"] };
-        this.width = src['width'];
+		this.width = src["width"];
-        this.height = src['height'];
+		this.height = src["height"];
 	}
 }
 

lib/controls/KeyControls.js

@@ -9,7 +9,7 @@ class KeyControls {
 			}
 			this.keys[e.which] = true;
 		}, false);
-    document.addEventListener('keyup', e => {
+		document.addEventListener("keyup", e => {
 			this.keys[e.which] = false;
 		}, false);
 	}

lib/controls/MouseControls.js

@@ -7,9 +7,9 @@ class MouseControls {
 		this.pressed = false;
 		this.released = false;
 		// Handlers
-    document.addEventListener('mousemove', this.move.bind(this), false);
+		document.addEventListener("mousemove", this.move.bind(this), false);
-    document.addEventListener('mousedown', this.down.bind(this), false);
+		document.addEventListener("mousedown", this.down.bind(this), false);
-    document.addEventListener('mouseup', this.up.bind(this), false);
+		document.addEventListener("mouseup", this.up.bind(this), false);
 	}
 
 	mousePosFromEvent({ clientX, clientY }) {

lib/index.js

@@ -1,4 +1,6 @@
-var Container = require("./Container.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"),
@@ -17,7 +19,9 @@ var Container = require("./Container.js"),
 ;
 
 module.exports = {
+	AnimManager,
 	CanvasRenderer,
+	Camera,
 	Container,
 	Game,
 	math,

lib/renderer/CanvasRenderer.js

@@ -10,11 +10,11 @@ class CanvasRenderer {
 	}
 
 	setPixelated() {
-    this.ctx['imageSmoothingEnabled'] = false;       /* standard */
+		this.ctx["imageSmoothingEnabled"] = false;       /* standard */
-    this.ctx['mozImageSmoothingEnabled'] = false;    /* Firefox */
+		this.ctx["mozImageSmoothingEnabled"] = false;    /* Firefox */
-    this.ctx['oImageSmoothingEnabled'] = false;      /* Opera */
+		this.ctx["oImageSmoothingEnabled"] = false;      /* Opera */
-    this.ctx['webkitImageSmoothingEnabled'] = false; /* Safari */
+		this.ctx["webkitImageSmoothingEnabled"] = false; /* Safari */
-    this.ctx['msImageSmoothingEnabled'] = false;     /* IE */
+		this.ctx["msImageSmoothingEnabled"] = false;     /* IE */
 	}
 
 	render(container, clear = true) {
@@ -78,7 +78,7 @@ class CanvasRenderer {
 						);
 					} else if (child.style && child.w && child.h) { 
 						ctx.fillStyle = child.style.fill; 
-            ctx.fillRect(0, 0, child.w, child.h)
+						ctx.fillRect(0, 0, child.w, child.h);
 					} else {
 						ctx.drawImage(img, 0, 0);
 					}
@@ -89,7 +89,7 @@ class CanvasRenderer {
 					renderRec(child);
 				}
 				ctx.restore();
-      })
+			});
 		}
 		if (clear) {
 			ctx.clearRect(0, 0, this.w, this.h);

lib/utilities/entity.js

@@ -1,5 +1,5 @@
-const math = require('./math');
+const math = require("./math");
-const Rect = require('../Rect');
+const Rect = require("../Rect");
 
 function addDebug(e) {
 	e.children = e.children || [];

lib/utilities/math.js

@@ -1,3 +1,22 @@
+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));
 }
@@ -19,6 +38,9 @@ function randOneIn(max = 2) {
 }
 
 module.exports = {
+	angle,
+	clamp,
+	distance,
 	rand,
 	randf,
 	randOneFrom,

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"
+  }
 }