ライフゲーム

life.js

var SCREEN_WIDTH = 848;
var SCREEN_HEIGHT = 576;
var SIDE_CELLS = 300;
var CELL_SIZE = SCREEN_WIDTH / SIDE_CELLS;
var FPS = 10;
var canvas;
var context;

window.onload = function() {

    var n = SIDE_CELLS * Math.floor(SIDE_CELLS * (SCREEN_HEIGHT/SCREEN_WIDTH) );
    var field = new Array(n);
    var tempField = new Array(n);

    for (var i = 0; i < field.length; i++) field[i] = Math.floor(Math.random()*2);
    
    canvas = document.getElementById('ocean');
    canvas.width = SCREEN_WIDTH;
    canvas.height = SCREEN_HEIGHT;
    context = canvas.getContext('2d');
    context.fillStyle = 'rgb(73,102,45)';

    update(field, tempField);
}

function update(field, tempField) {

    var n = 0;
    
    tempField = field.slice();

    for (var i = 0; i < tempField.length; i++) {
        n = 0;

        for (var x = -1; x < 2; x++) {
            for (var y = -1; y < 2; y++) {

                if (x==0 && y==0) continue;

                var c = i + x*SIDE_CELLS + y;
                if (c>=0 && c<tempField.length) {
                    if (i<c && c%SIDE_CELLS != 0 || i>c && c%SIDE_CELLS != SIDE_CELLS-1) {
                    
                        if (tempField[c]) n++;
                    }
                }
            }
        }

        if (tempField[i] && (n==2 || n==3)) {
            field[i] = 1;
        } else if (!tempField[i] && n==3) {
            field[i] = 1;
        } else field[i] = 0;
    }
    
    draw(field);
    setTimeout(update, 1000/FPS, field, tempField);
    }

function draw(field) {

    context.clearRect(0, 0, SCREEN_WIDTH, SCREEN_HEIGHT);
    for (var i = 0; i < field.length; i++) {
        if (field[i]) context.fillRect( (i%SIDE_CELLS)*CELL_SIZE, Math.floor((i/SIDE_CELLS))*CELL_SIZE, CELL_SIZE, CELL_SIZE);
    }
}