82 lines
2.4 KiB
TypeScript
82 lines
2.4 KiB
TypeScript
import { Point, resizeCanvas } from "./common.js"
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const WIDTH = 800;
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const HEIGHT = 600;
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const SCALING = 4;
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const DIRECTIONS: Point[] = [
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{ x: 0, y: -1}, // N
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{ x: -1, y: -1}, // NW
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{ x: 1, y: -1}, // NE
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{ x: -1, y: 0}, // W
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{ x: 1, y: 0}, // E
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{ x: 0, y: 1}, // S
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{ x: -1, y: 1}, // SW
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{ x: 1, y: 1}, // SE
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]
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function add2(p1: Point, p2: Point) {
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return { x: p1.x + p2.x, y: p1.y + p2.y };
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}
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function init() {
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const canvas = document.getElementById("canvas") as HTMLCanvasElement | null;
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if (!canvas) throw new Error("unable to get canvas HTML element");
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const ctx = canvas.getContext("2d", { alpha: false }) as CanvasRenderingContext2D | null;
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if (!ctx) throw new Error("unable to get canvas 2D context");
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ctx.canvas.width = WIDTH
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ctx.canvas.height = HEIGHT
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const cells = new Array(WIDTH * HEIGHT / SCALING)
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cells.fill(0)
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const state = new Array(WIDTH * HEIGHT / SCALING)
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state.fill(0)
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for (let i=0; i < WIDTH * HEIGHT / SCALING; i++) state[i] = +(Math.random() * 4 < 1)
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console.log(state.length)
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//window.addEventListener('resize', () => resizeCanvas(ctx));
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window.requestAnimationFrame(t => update(ctx, cells, state));
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}
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// update loop, called every frame
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function update(ctx: CanvasRenderingContext2D, cells: number[], state: number[]) {
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ctx.clearRect(0, 0, WIDTH, HEIGHT);
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for (let i=0; i < WIDTH * HEIGHT / SCALING; i++) cells[i] = state[i];
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const cell = (p: Point) => cells[p.y*WIDTH/SCALING + p.x]
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ctx.beginPath(); // batch draw calls, only once per frame
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ctx.fillStyle = "white";
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for (let y=1; y < HEIGHT - 1; y++) {
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for (let x=1; x < WIDTH - 1; x++) {
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const p = { x, y };
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// count neighbors
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let neighbors = 0;
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for (const d of DIRECTIONS) {
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const pos = add2(p, d);
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neighbors += cell(pos);
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}
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if (cell(p) == 1) {
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state[p.y*WIDTH/SCALING+p.x] = +(neighbors == 2 || neighbors == 3)
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} else {
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state[p.y*WIDTH/SCALING+p.x] = +(neighbors == 3)
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}
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if (cell(p) == 1) {
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ctx.moveTo(p.x, p.y);
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ctx.rect(p.x, p.y, SCALING, SCALING);
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}
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}
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}
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ctx.fill(); // draw only once per frame
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window.requestAnimationFrame(t => update(ctx, cells, state));
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}
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init();
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