var counter = 0;

var PIXEL_SIZE = 4;

var temp_1 = 0;

function init()

{

    setInterval('render()',50);

}

function dist(a, b, c, d)

{

    return Math.sqrt((a - c) * (a - c) + (b - d) * (b - d));

}

function render()

{

    var canvas = document.getElementById('tutorial');

    canvas.resize(128, 128);

    var ctx = canvas.getContext('2d');

    ctx.save();

    var time = counter * 5;

    for( y = 0; y < 128; y+=PIXEL_SIZE) {

	for( x = 0 ; x < 128; x+=PIXEL_SIZE) {

	    var temp_val = Math.floor(Math.sin(dist(x + time, y, 128.0, 128.0) / 8.0)

				      + Math.sin(dist(x, y, 64.0, 64.0) / 8.0)

				      + Math.sin(dist(x, y + time / 7, 192.0, 64) / 7.0)

				      + Math.sin(dist(x, y, 192.0, 100.0) / 8.0));

	    var temp_col = Math.floor((2 + temp_val) * 50);

	    var rand_red = temp_col * 3;

	    var rand_green = temp_col  ;

	    var rand_blue = 128 - temp_col;

	    ctx.fillStyle = "rgb("+rand_red+","+rand_green+","+rand_blue+")";

	    ctx.fillRect(x,y,PIXEL_SIZE,PIXEL_SIZE);

	}

    }

    ctx.restore();

    counter++;

}

init();