returns 1 if a line segment intersects a circle. returns 0 otherwise. (note: uses polar coordinates.)

line_circle_collision.c

int line_seg_circ_polar(float er, float etheta, float cr, float ctheta, float cradius)
{
	if (cradius >= cr) return 1;
	if (fabsf(etheta - ctheta) > asinf(cradius / cr)) return 0;
	if (er * er < cr * cr - cradius * cradius && er * er + cr * cr - 2 * er * cr * cosf(etheta - ctheta) > cradius * cradius) return 0;
	return 1;
}