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balls4.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<!-- <meta name="viewport" content="initial-scale=1.0; maximum-scale=1.0; user-scalable=0;"/> -->
<title>Elastic Balls</title>
<link rel="image_src" href="/img/balls3.png" />
<style type="text/css">
body { background-color: #444; color: #CCC; margin: 0px; overflow: hidden; font-family: monospace;}
#info { top: 0px; width: 100%; color: #777; padding: 5px; text-align:center; }
#container { text-align:center; }
#container canvas { border:0px solid #777; }
div { text-align:center; }
</style>
</head>
<body>
<br/>
<div id="container"></div>
<div>
<span id="label"></span><br/>
<script type="text/javascript">
function Ball() {
this.x = 0;
this.y = 0;
this.sx = 0;
this.sy = 0;
this.size = 10;
this.mass = function() {
return(this.size*this.size*Math.PI);
}
this.r = 128;
this.g = 128;
this.b = 128;
this.a = 0.75;
this.color = function(r,g,b,a) {
if (r == 'x') {
return(this.r.toString(16)+this.g.toString(16)+this.b.toString(16));
} else if ( undefined != r) {
this.r = r;
this.g = g;
this.b = b;
if ( undefined != a) {
this.a = a;
}
} else {
return("rgba("+this.r+","+this.g+","+this.b+","+this.a+")");
}
}
}
var canvas, canvas2, context, image, data, context2;
var balls = [];
var WIDTH = 800;
var HEIGHT = 800;
var BALLCOUNT = 256;
init();
setInterval(loop, 1000 / 60);
function init() {
var container;
container = document.getElementById('container');
canvas = document.createElement("canvas");
canvas.width = WIDTH;
canvas.height = HEIGHT;
canvas.style.width = WIDTH + "px";
canvas.style.height = HEIGHT + "px";
container.appendChild(canvas);
context = canvas.getContext("2d");
context.fillStyle = "rgb(0, 0, 0)";
context.fillRect (0, 0, WIDTH, HEIGHT);
image = context.getImageData(0, 0, WIDTH, HEIGHT);
data = image.data;
canvas2 = document.createElement("canvas");
canvas2.width = WIDTH;
canvas2.height = HEIGHT;
context2 = canvas2.getContext("2d");
for (var i = 0; i < BALLCOUNT; i++) {
balls[i] = new Ball();
// balls[i].x = Math.random() * WIDTH;
// balls[i].y = Math.random() * HEIGHT;
balls[i].x = (i % 16) * (WIDTH / 16) + 25 + i / 16;
balls[i].y = Math.floor(i / 16) * (HEIGHT / 16) + 25;
// balls[i].sx = Math.random() * 4 - 2;
// balls[i].sy = Math.random() * 4 - 2;
balls[i].sx = 2 * Math.pow(-1,Math.floor(Math.random()*2)+1);
balls[i].sy = 3;
// balls[i].size = Math.random() * 20 + 10;
balls[i].size = 18;
balls[i].size = 8;
// if (Math.floor(Math.random()*2) == 0) { balls[i].color(127,127,127); } else { balls[i].color(255,255,255); }
if ((i % 2) == 0) { balls[i].color(127,127,127); } else { balls[i].color(255,255,255); }
}
canvas.addEventListener('click', function(event) {
for (var i = 0; i < balls.length; i++) {
var x = event.pageX - canvas.offsetLeft;
var y = event.pageY - canvas.offsetTop;
if (Math.sqrt(Math.pow(x - balls[i].x,2) + Math.pow(y - balls[i].y,2)) <= balls[i].size) {
/*
var r = Math.floor(Math.random()*3);
if (r == 2) {
balls[i].color(255,128,128);
} else if (r == 1) {
balls[i].color(128,255,128);
} else {
balls[i].color(128,128,255);
}
*/
alert(balls[i].color('x'));
}
}
}, false);
}
function loop() {
// Clear the buffer;
context2.fillStyle="rgba(0,0,0,1)";
context2.fillRect(0,0,WIDTH,HEIGHT);
// Boundary collision
for (var i = 0; i < balls.length; i++) {
if (((balls[i].x - balls[i].size < 0) && (balls[i].sx < 0)) ||
((balls[i].x + balls[i].size > WIDTH) && balls[i].sx > 0)) {
balls[i].sx *= -1;
}
if (((balls[i].y - balls[i].size < 0) && (balls[i].sy < 0)) ||
((balls[i].y + balls[i].size > HEIGHT) && balls[i].sy > 0)) {
balls[i].sy *= -1;
}
}
// Ball collision --- Slowly steps through each pair of balls.
for (var i = 0; i < balls.length - 1; i++) {
for (var j = i + 1; j < balls.length; j++) {
if ((Math.pow(balls[i].x - balls[j].x,2) + Math.pow(balls[i].y - balls[j].y,2)) <= Math.pow(balls[i].size + balls[j].size,2)) {
// Collision Detected
var ri,rj;
if (balls[i].sx*balls[i].sx+balls[i].sy*balls[i].sy > balls[j].sx*balls[j].sx+balls[j].sy*balls[j].sy) {
ri = 10; rj = 20;
} else {
ri = 20; rj = 10;
}
// Determine Unit Normal Velocity.
var unx = balls[j].x - balls[i].x;
var uny = balls[j].y - balls[i].y;
var nc = Math.sqrt(unx*unx + uny*uny);
unx /= nc;
uny /= nc;
// Skip if they're already moving away from each other.
if ((balls[j].sx - balls[i].sx) * unx + (balls[j].sy - balls[i].sy) * uny > 0) { continue; }
// Unit Tangenital Velocity.
var utx = uny * -1;
var uty = unx;
var v1n = unx * balls[i].sx + uny * balls[i].sy;
var v1t = utx * balls[i].sx + uty * balls[i].sy;
var v2n = unx * balls[j].sx + uny * balls[j].sy;
var v2t = utx * balls[j].sx + uty * balls[j].sy;
// We're using the circle's area as the ball's mass.
var m1 = balls[i].mass();
var m2 = balls[j].mass();
var vv1n = (v1n * (m1 - m2) + 2 * m2 * v2n) / (m1 + m2);
var vv2n = (v2n * (m2 - m1) + 2 * m1 * v1n) / (m1 + m2);
balls[i].sx = unx * vv1n + utx * v1t;
balls[i].sy = uny * vv1n + uty * v1t;
balls[j].sx = unx * vv2n + utx * v2t;
balls[j].sy = uny * vv2n + uty * v2t;
/*
if (balls[i].r < balls[j].r) { ++balls[i].r; --balls[j].r; ++balls[i].g; --balls[j].b;} else if (balls[i].r > balls[j].r) { --balls[i].r; ++balls[j].r; --balls[i].g; ++balls[j].b;}
if (balls[i].g < balls[j].g) { ++balls[i].g; --balls[j].g; ++balls[i].b; --balls[j].r;} else if (balls[i].g > balls[j].g) { --balls[i].g; ++balls[j].g; --balls[i].b; ++balls[j].r;}
if (balls[i].b < balls[j].b) { ++balls[i].b; --balls[j].b; ++balls[i].r; --balls[j].g;} else if (balls[i].b > balls[j].b) { --balls[i].b; ++balls[j].b; --balls[i].r; ++balls[j].g;}
*/
var r1 = balls[i].r;
var g1 = balls[i].g;
var b1 = balls[i].b;
var r2 = balls[j].r;
var g2 = balls[j].g;
var b2 = balls[j].b;
if (Math.floor(Math.random()*rj) == 0) { balls[i].r = r2; };
if (Math.floor(Math.random()*rj) == 0) { balls[i].g = g2; };
if (Math.floor(Math.random()*rj) == 0) { balls[i].b = b2; };
if (Math.floor(Math.random()*ri) == 0) { balls[j].r = r1; };
if (Math.floor(Math.random()*ri) == 0) { balls[j].g = g1; };
if (Math.floor(Math.random()*ri) == 0) { balls[j].b = b1; };
}
}
}
// Draw the balls.
for (var i = 0; i < balls.length; i++) {
balls[i].x += balls[i].sx;
balls[i].y += balls[i].sy;
context2.fillStyle=balls[i].color();
context2.beginPath();
context2.arc(Math.floor(balls[i].x),Math.floor(balls[i].y),balls[i].size,0,Math.PI*2,true);
context2.fill();
if (i == 0) {
context2.strokeStyle="rgba(255,255,255,1)";
context2.lineWidth=2;
context2.beginPath();
context2.arc(Math.floor(balls[i].x),Math.floor(balls[i].y),balls[i].size*2,0,Math.PI*2,true);
context2.stroke();
}
}
// Page flip to the on-screen canvas. Is page-flipping even necessary?
// Old frame buffer habits die hard.
out();
context.drawImage(canvas2,0,0,WIDTH,HEIGHT);
}
function energy() {
var ke = 0;
for (var i = 0; i < balls.length; i++) {
var m = balls[i].mass();
ke += m / 2 * (balls[i].sx*balls[i].sx+balls[i].sy*balls[i].sy);
}
return ke;
}
function out() {
var r = g = b = c = m = y = k = w = 0;
for (var i = 0; i < balls.length; i++) {
switch(balls[i].color('x')) {
case '7f7f7f':
++k; break;
case '7f7fff':
++b; break;
case '7fff7f':
++g; break;
case '7fffff':
++c; break;
case 'ff7f7f':
++r; break;
case 'ff7fff':
++m; break;
case 'ffff7f':
++y; break;
case 'ffffff':
++w;
}
}
document.getElementById('label').innerHTML = 'Black: '+k+' Blue: '+b+' Green: '+g+' Cyan: '+c+' Red: '+r+' Magenta: '+m+' Yellow: '+y+' White: '+w;
}
</script>
</body>
</html>