package mx

// The type describes a simple
// math circle.
type Circle struct {
	Center Vector
	Radius Float
}

func (c Circle) ContainsPoint(
	pt Vector,
) bool {
	d := c.Center.Sub(pt)
	dx, dy := d.XY()
	d2 := dx*dx + dy*dy
	r2 := c.Radius*c.Radius
	return r2 > d2
}

func (c Circle) GetContainedPoints(
	pts Vectors,
) Vectors {
	ret := make(Vectors, 0, len(pts))
	for _, pt := range pts {
		if c.ContainsPoint(pt) {
			ret = append(ret, pt)
		}
	}

	return ret
}