function mouseUp() {
    document.body.onmousemove = null;
}

function mouseDown() {
    var oldx = event.pageX
    var oldy = event.pageY

    function mouseMove() {
	var x = event.pageX
	var y = event.pageY
	
	var tx = x - oldx;
	var ty = y - oldy;

	var r = Math.sqrt(tx*tx + ty*ty);
	if(r) { var rotmat = new J3DIMatrix4();rotmat.rotate(r/10, ty/r, tx/r, 0)
		rotmat.multiply(matrix);
		matrix=rotmat;
	      }
	oldx = x;
	oldy = y;
	
    }
    document.body.onmousemove = mouseMove;

}

function mouseMove() {
    var x = event.pageX
    var y = event.pageY

    
    


}