circle vs line segment intersection check

circle_vs_segment.cpp

bool Circle::intersect(const Segment2D &segment, vec2 &n, float &t) const {
	vec2 ap = center - segment.a;
	vec2 ab = segment.b - segment.a;

	float dab = ab.dot(ab);
	if (dab == 0.0f) return false;

	t = clamp(ap.dot(ab) / dab, 0.0f, 1.0f);
	n = center - (segment.a + ab * t);
	t = n.length2();
	if (t > radius * radius)
		return false;
	n = n.normal();
	t = radius - sqrtf(t);
	return true;
}