draw2dkit/draw2dkit.go
func Ellipse(path draw2d.PathBuilder, cx, cy, rx, ry float64) {
	path.ArcTo(cx, cy, rx, ry, 0, -math.Pi*2)
	path.Close()
}
func Ellipse(path draw2d.PathBuilder, cx, cy, rx, ry float64) {
	path.ArcTo(cx, cy, rx, ry, 0, -math.Pi*2)
	path.Close()
}
// Ellipse draws an ellipse using a path with center (cx,cy) and radius (rx,ry)