class com.lo9ic.Quaternion {
	private var $x, $y, $z, $w:Number;
	
	function Quaternion(a:Number, b:Number, c:Number, d:Number) {
		$x = a ? a : 0;
		$y = b ? b : 0;
		$z = c ? c : 0;
		$w = d ? d : 1;
	}
	
	public function get x():Number {
		return $x;
	}
	
	public function get y():Number {
		return $y;
	}
	
	public function get z():Number {
		return $z;
	}

	public function get w():Number {
		return $w;
	}

	public function fromPoint(a:Number, b:Number, c:Number):Void {
		$x = a;
		$y = b;
		$z = c;
		$w = 0;
	}
				
	public function fromAxisAngle(a:Number, b:Number, c:Number, d:Number):Void {
		var ca = Math.cos(d/2); var sa = Math.sin(d/2);
		var m = Math.sqrt(a*a + b*b + c*c);
		$x = a/m * sa;
		$y = b/m * sa;
		$z = c/m * sa;
		$w = ca;
	}
				
	public function concat(q:Quaternion):Void {
		var w1 = $w; var x1 = $x; var y1 = $y; var z1 = $z;
		var w2 = q.w; var x2 = q.x; var y2 = q.y; var z2 = q.z;
		$w = w1*w2 - x1*x2 - y1*y2 - z1*z2
		$x = w1*x2 + x1*w2 + y1*z2 - z1*y2
		$y = w1*y2 + y1*w2 + z1*x2 - x1*z2
		$z = w1*z2 + z1*w2 + x1*y2 - y1*x2
	}
	
	public function invert():Void {
		$x = -$x;
		$y = -$y;
		$z = -$z;
	}

	public function copy():Quaternion {
		return new Quaternion($x, $y, $z, $w);
	}
}