func RectFromCircle(c Vec, r float64) Rectangle {
	return RectWH(c.X-r, c.Y-r, 2*r, 2*r)
}
func RectFromCircle(c Vec, r float64) Rectangle {
	return RectWH(c.X-r, c.Y-r, 2*r, 2*r)
}
func RectFromCircle ( c Vec , r float64 ) Rectangle { return RectWH ( c . X - r , c . Y - r , 2 * r , 2 * r ) }
// RectFromCircle returns the minimum rectangle that contains the circle of
// center c and radius r
RectFromCircle returns the minimum rectangle that contains the circle of center c and radius r