function rect (x0,y0,x1,y1){
	if (x0 instanceof vec2) {
		this.x = x0
		this.y = y0
	}
	else if (x1 === undefined) {
		this.x = new vec2(x0,x0)
		this.y = new vec2(y0,y0)
	}
	else {
		this.x = new vec2(x0,x1)
		this.y = new vec2(y0,y1)
	}
	this.translation = new vec2(0,0)
}
rect.prototype.clone = function(){
	return new rect( this.x.clone(), this.y.clone() )
}
rect.prototype.center = function(){
	return new vec2(this.x.midpoint(), this.y.midpoint())
}
rect.prototype.area = function(){
	return this.x.length() * this.y.length()
}
rect.prototype.normalize = function(){
	this.x.abs().add(this.translation.a)
	this.y.abs().add(this.translation.b)
	this.translation.a = this.translation.b = 0
	return this
}
rect.prototype.contains = function(x,y){
	return this.x.contains(x) && this.y.contains(y)
}
rect.prototype.intersects = function(r){
	return this.x.intersects(r.x) && this.y.intersects(r.y)
}
rect.prototype.width = function(){ return this.x.length() }
rect.prototype.height = function(){ return this.y.length() }
rect.prototype.fill = function(){
	ctx.fillRect(this.x.a + this.translation.a, this.y.a + this.translation.b, this.x.length(), this.y.length())
}
rect.prototype.stroke = function(){
	ctx.beginPath()
	ctx.moveTo(this.x.a, this.y.a)
	ctx.lineTo(this.x.b, this.y.b)
	ctx.stroke()
}
rect.prototype.perimeter = function(){
	line( this.x.a, this.y.a, this.x.b, this.y.a, this.translation )
	line( this.x.a, this.y.b, this.x.b, this.y.b, this.translation )
	line( this.x.a, this.y.a, this.x.a, this.y.b, this.translation )
	line( this.x.b, this.y.a, this.x.b, this.y.b, this.translation )
}
rect.prototype.toString = function(){
	return "[" + this.x.toString() + " " + this.y.toString() + "]"
}
rect.prototype.quantize = function(n){
	this.x.quantize(n)
	this.y.quantize(n)
}
rect.prototype.reset = function(){
	var copy = this.clone()
	copy.sides = 0xf
	this.regions = [ copy ]
}
rect.prototype.clipTo = function(r){
	// for each of this rect's regions split the region if necessary
	var regions = this.regions
	var splits
	for (var i = 0, len = regions.length; i < len; i++) {
		if (regions[i] && regions[i].intersects(r)) {
			splits = regions[i].split(r)
			regions = regions.concat(splits)
			regions[i] = null
		}
	}
	this.regions = regions
}
rect.prototype.split = function(r){
	var splits = []
	var x_intervals = [], y_intervals = []

	// Split vertically
	if (this.x.contains(r.x.a) && r.x.contains(this.x.b)) {
		x_intervals.push( new vec2( this.x.a,    r.x.a ))
		x_intervals.push( new vec2(    r.x.a, this.x.b ))
	}

	else if (r.x.contains(this.x.a) && this.x.contains(r.x.b)) {
		x_intervals.push( new vec2( this.x.a,    r.x.b ))
		x_intervals.push( new vec2(    r.x.b, this.x.b ))
	}
	
	else if (this.x.contains(r.x.a) && this.x.contains(r.x.b)) {
		x_intervals.push( new vec2( this.x.a,    r.x.a ))
		x_intervals.push( new vec2(    r.x.a, 	 r.x.b ))
		x_intervals.push( new vec2(    r.x.b, this.x.b ))
	}

	else { // if (r.x.contains(this.x.a) && r.x.contains(r.x.b)) {
		x_intervals.push( new vec2( this.x.a, this.x.b ))
	}


	// Split horizontally
	if (this.y.contains(r.y.a) && r.y.contains(this.y.b)) {
		y_intervals.push( new vec2( this.y.a,    r.y.a ))
		y_intervals.push( new vec2(    r.y.a, this.y.b ))
	}

	else if (r.y.contains(this.y.a) && this.y.contains(r.y.b)) {
		y_intervals.push( new vec2( this.y.a,    r.y.b ))
		y_intervals.push( new vec2(    r.y.b, this.y.b ))
	}
	
	else if (this.y.contains(r.y.a) && this.y.contains(r.y.b)) {
		y_intervals.push( new vec2( this.y.a,    r.y.a ))
		y_intervals.push( new vec2(    r.y.a, 	 r.y.b ))
		y_intervals.push( new vec2(    r.y.b, this.y.b ))
	}

	else { // if (r.y.contains(this.y.a) && this.y.contains(r.y.b)) {
		y_intervals.push( new vec2( this.y.a, this.y.b ))
	}

	x_intervals.forEach(function(x){
		y_intervals.forEach(function(y){
			splits.push(new rect(x,y))
		})
	})

	return splits
}
zz = false
document.body.addEventListener("click", function(){ zz = true })