f64/d2/vec.go
func (v Vec) In(r Rectangle) bool {
	return r.Min.X <= v.X && v.X < r.Max.X &&
		r.Min.Y <= v.Y && v.Y < r.Max.Y
}
func (v Vec) In(r Rectangle) bool {
	return r.Min.X <= v.X && v.X < r.Max.X &&
		r.Min.Y <= v.Y && v.Y < r.Max.Y
}
func ( v Vec ) In ( r Rectangle ) bool { return r . Min . X <= v . X && v . X < r . Max . X && r . Min . Y <= v . Y && v . Y < r . Max . Y }
// In reports whether p is in r.
In reports whether p is in r .