split out engine components

src/components/snake/canvas.ts

@@ -1,4 +1,4 @@
-import { Engine, randint, Vec2, vec2 } from './game-engine';
+import { Engine, Keys, randint, UI, Vec2, vec2 } from './game-engine';
 
 const BOARD_SIZE = 600; // px
 const SQUARE_SIZE = 30; // px
@@ -6,21 +6,43 @@ const SQUARE_SIZE = 30; // px
 const BOARD_SQUARES = BOARD_SIZE / SQUARE_SIZE;
 
 export default function runCanvas(canvas: HTMLCanvasElement) {
-    const engine = new Engine(canvas);
+    const ui = new UI(canvas);
+	const keys = new Keys();
+    const engine = new Engine({ updateDelay: 200 });
 
-    let dead = false;
-    const snake = [vec2(1, 1), vec2(2, 1)];
-    let apple = vec2(8, 8);
+	// game logic --------------------------------------------------------------
 
-    function clearCanvas() {
-        engine.rect(0, 0, canvas.width, canvas.height);
-    }
-    function drawSquare(pos: Vec2) {
-        engine.rect(pos.x * SQUARE_SIZE, pos.y * SQUARE_SIZE, SQUARE_SIZE, SQUARE_SIZE);
-    }
+	function getRandApplePos() {
+		return vec2(randint(0, BOARD_SQUARES), randint(0, BOARD_SQUARES))
+	}
+
+	function calcUpdateDelay(snakeLength: number) {
+		// 5 squares per second base (200ms) + 1 sps on every apple
+		return 1000 / (5 + snakeLength)
+	}
+
+	function resetState() {
+		let dead = false;
+		const snake = [vec2(1, 1), vec2(2, 1)];
+		let apple = getRandApplePos();
+
+		engine.setUpdateDelay(calcUpdateDelay(snake.length))
+
+		return { dead, snake, apple };
+	}
+
+	let state = resetState();
+
+    function update() {
+		const { dead, snake, apple } = state;
+
+        if (dead) {
+			if (keys.isKeyPressed(' ')) {
+				state = resetState();
+			}
+			return;
+		}
 
-    async function update() {
-        if (dead) return;
 
         let dir = snake[snake.length - 1]!.sub(snake[snake.length - 2]!);
         const keyDirMap = {
@@ -30,7 +52,7 @@ export default function runCanvas(canvas: HTMLCanvasElement) {
             d: vec2(+1, 0),
         };
         for (const [key, newDir] of Object.entries(keyDirMap)) {
-            if (engine.isKeyPressed(key) && Vec2.dot(dir, newDir) === 0) {
+            if (keys.isKeyPressed(key) && Vec2.dot(dir, newDir) === 0) {
                 dir = newDir;
                 break;
             }
@@ -40,45 +62,58 @@ export default function runCanvas(canvas: HTMLCanvasElement) {
         // check for snake intersection
         for (const square of snake.slice(1)) {
             if (nextHead.eq(square)) {
-                dead = true;
+                state.dead = true;
             }
         }
 
         // check for snake out of bounds
         if (nextHead.x < 0 || nextHead.x >= BOARD_SQUARES || nextHead.y < 0 || nextHead.y >= BOARD_SQUARES) {
-            dead = true;
+            state.dead = true;
         }
 
         // check for snake hitting apple
         if (nextHead.eq(apple)) {
-            apple = vec2(randint(0, BOARD_SQUARES), randint(0, BOARD_SQUARES));
+            state.apple = getRandApplePos();
+			engine.setUpdateDelay(calcUpdateDelay(snake.length))
         } else {
             snake.shift();
         }
 
         // move the snake
         snake.push(nextHead);
+
+		keys.update();
     }
 
-    async function render() {
-        engine.setFillStyle('#333333');
+	// rendering ---------------------------------------------------------------
+    function clearCanvas() {
+        ui.rect(0, 0, canvas.width, canvas.height);
+    }
+    function drawSquare(pos: Vec2) {
+        ui.rect(pos.x * SQUARE_SIZE, pos.y * SQUARE_SIZE, SQUARE_SIZE, SQUARE_SIZE);
+    }
+    function render() {
+		const { dead, snake, apple } = state;
+
+        ui.setFillStyle('#333333');
         clearCanvas();
 
-        engine.setFillStyle('#277edb');
+        ui.setFillStyle('#277edb');
         for (const square of snake.slice(0, snake.length - 1)) {
             drawSquare(square);
         }
-        engine.setFillStyle('#29d17a');
+        ui.setFillStyle('#29d17a');
         drawSquare(snake[snake.length - 1]!);
 
-        engine.setFillStyle('#e01851');
+        ui.setFillStyle('#e01851');
         drawSquare(apple);
 
         if (dead) {
-            engine.setFillStyle('#ff0000');
-            engine.text('You Died', 60, 60);
+            ui.setFillStyle('#ff0000');
+            ui.text('You Died', 60, 60);
         }
     }
 
+	keys.bindKeys()
     engine.run(update, render);
 }

src/components/snake/game-engine.ts

@@ -73,14 +73,50 @@ export function vec2(x: number, y: number) {
     return new Vec2(x, y);
 }
 
-export class Engine {
-    ctx: CanvasRenderingContext2D;
-
-    camera = vec2(0, 0);
+export class Keys {
     keys = new Set<string>();
     keysPressed = new Set<string>();
     keysReleased = new Set<string>();
 
+    isKeyDown(key: string) {
+        return this.keys.has(key);
+    }
+
+    isKeyUp(key: string) {
+        // by default, keys are considered up
+        return !this.keys.has(key);
+    }
+
+    isKeyPressed(key: string) {
+        return this.keysPressed.has(key);
+    }
+
+    isKeyReleased(key: string) {
+        return this.keysReleased.has(key);
+    }
+
+    bindKeys() {
+        document.addEventListener('keydown', (event: KeyboardEvent) => {
+            this.keys.add(event.key);
+            this.keysPressed.add(event.key);
+        });
+        document.addEventListener('keyup', (event: KeyboardEvent) => {
+            this.keys.delete(event.key);
+            this.keysReleased.add(event.key);
+        });
+    }
+
+	update() {
+		this.keysPressed.clear();
+		this.keysReleased.clear();
+	}
+}
+
+export class UI {
+    ctx: CanvasRenderingContext2D;
+
+    camera = vec2(0, 0);
+
     constructor(canvasElement: HTMLCanvasElement) {
         const ctx = canvasElement.getContext('2d');
         if (ctx === null) throw Error('unable to get 2d canvas context');
@@ -100,49 +136,29 @@ export class Engine {
         const c = this.camera;
         this.ctx.fillText(text, x - c.x, y - c.y);
     }
+}
 
-    isKeyDown(key: string) {
-        return this.keys.has(key);
-    }
+export class Engine {
+	updateDelay: number
 
-    isKeyUp(key: string) {
-        // by default, keys are considered up
-        return !this.keys.has(key);
-    }
+	constructor({ updateDelay }: { updateDelay: number }) {
+		this.updateDelay = updateDelay;
+	}
 
-    isKeyPressed(key: string) {
-        return this.keysPressed.has(key);
-    }
-
-    isKeyReleased(key: string) {
-        return this.keysReleased.has(key);
-    }
-
-    private bindKeys() {
-        document.addEventListener('keydown', (event: KeyboardEvent) => {
-            this.keys.add(event.key);
-            this.keysPressed.add(event.key);
-        });
-        document.addEventListener('keyup', (event: KeyboardEvent) => {
-            this.keys.delete(event.key);
-            this.keysReleased.add(event.key);
-        });
-    }
-
-    run(update: () => Promise<void>, render: () => Promise<void>) {
-        this.bindKeys();
+	setUpdateDelay(updateDelay: number) {
+		this.updateDelay = updateDelay;
+	}
 
+    run(update: () => void, render: () => void) {
         const updateLoop = async () => {
             // eslint-disable-next-line no-constant-condition
             while (true) {
-                await update();
-                this.keysPressed.clear();
-                await new Promise(resolve => setTimeout(resolve, 100));
-                await new Promise(resolve => setTimeout(resolve, 0));
+                update();
+                await new Promise(resolve => setTimeout(resolve, this.updateDelay));
             }
         };
         const renderLoop = async () => {
-            await render();
+            render();
             window.requestAnimationFrame(renderLoop);
         };