document.getElementById('close').onmousedown = function(e) {
e.preventDefault();
document.getElementById('info').style.display = 'none';
return false;
};

// settings

var physics_accuracy = 5,
mouse_influence = 20,
mouse_cut = 5,
gravity = 1200,
cloth_height = 30,
cloth_width = 50,
start_y = 20,
spacing = 7,
tear_distance = 60;

window.requestAnimFrame =
window.requestAnimationFrame ||
window.webkitRequestAnimationFrame ||
window.mozRequestAnimationFrame ||
window.oRequestAnimationFrame ||
window.msRequestAnimationFrame ||
function(callback) {
window.setTimeout(callback, 1000 / 60);
};

var canvas,
ctx,
cloth,
boundsx,
boundsy,
mouse = {
down: false,
button: 1,
x: 0,
y: 0,
px: 0,
py: 0
};

window.onload = function() {

canvas = document.getElementById('c');
ctx    = canvas.getContext('2d');

canvas.width = canvas.clientWidth;
canvas.height = 376;

canvas.onmousedown = function(e) {
    mouse.button = e.which;
    mouse.px = mouse.x;
    mouse.py = mouse.y;

var rect = canvas.getBoundingClientRect();
mouse.x = e.clientX - rect.left,
mouse.y = e.clientY - rect.top,
mouse.down = true;
e.preventDefault();
};

canvas.onmouseup = function(e) {
    mouse.down = false;
    e.preventDefault();
};

canvas.onmousemove = function(e) {
    mouse.px = mouse.x;
    mouse.py = mouse.y;
    var rect = canvas.getBoundingClientRect();

mouse.x = e.clientX - rect.left,
mouse.y = e.clientY - rect.top,
e.preventDefault();
};

canvas.oncontextmenu = function(e) {
    e.preventDefault(); 
};

boundsx = canvas.width - 1;
boundsy = canvas.height - 1;

ctx.strokeStyle = 'rgba(222,222,222,0.6)';
cloth = new Cloth();
update();

};

var Point = function(x, y) {

this.x = x;
this.y = y;
this.px = x;
this.py = y;
this.vx = 0;
this.vy = 0;
this.pin_x = null;
this.pin_y = null;
this.constraints = [];

};

Point.prototype.update = function(delta) {

if (mouse.down) {

    var diff_x = this.x - mouse.x,
        diff_y = this.y - mouse.y,
        dist   = Math.sqrt(diff_x * diff_x + diff_y * diff_y);

    if (mouse.button == 1) {

        if(dist 

};

Point.prototype.draw = function() {

if (this.constraints.length 

};

Point.prototype.resolve_constraints = function() {

if (this.pin_x != null && this.pin_y != null) {

    this.x = this.pin_x;
    this.y = this.pin_y;
    return;
}

var i = this.constraints.length;
while(i--) this.constraints[i].resolve();

this.x > boundsx ? this.x = 2 * boundsx - this.x : 1 > this.x && (this.x = 2 - this.x);
this.y  boundsy && (this.y = 2 * boundsy - this.y);

};

Point.prototype.attach = function(point) {

this.constraints.push(
    new Constraint(this, point)
);

};

Point.prototype.remove_constraint = function(lnk) {

var i = this.constraints.length;
while(i--) if(this.constraints[i] == lnk) this.constraints.splice(i, 1);

};

Point.prototype.add_force = function(x, y ) {

this.vx += x;
this.vy += y;

};

Point.prototype.pin = function(pinx, piny) {
this.pin_x = pinx;
this.pin_y = piny;
};

var Constraint = function(p1, p2) {

this.p1 = p1;
this.p2 = p2;
this.length = spacing;

};

Constraint.prototype.resolve = function() {

var diff_x = this.p1.x - this.p2.x,
    diff_y = this.p1.y - this.p2.y,
    dist = Math.sqrt(diff_x * diff_x + diff_y * diff_y),
    diff = (this.length - dist) / dist;

if (dist > tear_distance) this.p1.remove_constraint(this);

var px = diff_x * diff * 0.5;
var py = diff_y * diff * 0.5;

this.p1.x += px;
this.p1.y += py;
this.p2.x -= px;
this.p2.y -= py;

};

Constraint.prototype.draw = function() {

ctx.moveTo(this.p1.x, this.p1.y);
ctx.lineTo(this.p2.x, this.p2.y);

};

var Cloth = function() {

this.points = [];

var start_x = canvas.width / 2 - cloth_width * spacing / 2;

for(var y = 0; y 

x != 0 && p.attach(this.points[this.points.length - 1]);
y == 0 && p.pin(p.x, p.y);
y != 0 && p.attach(this.points[x + (y - 1) * (cloth_width + 1)])

        this.points.push(p);
    }
}

};

Cloth.prototype.update = function() {

var i = physics_accuracy;

while(i--) {
    var p = this.points.length;
    while(p--) this.points[p].resolve_constraints();
}

i = this.points.length;
while(i--) this.points[i].update(.016);

};

Cloth.prototype.draw = function() {

ctx.beginPath();

var i = cloth.points.length;
while(i--) cloth.points[i].draw();

ctx.stroke();

};

function update() {

ctx.clearRect(0, 0, canvas.width, canvas.height);

cloth.update();
cloth.draw();

requestAnimFrame(update);

}//@ sourceURL=pen.js