My algorithm for sphere-cone intersection

gistfile1.cpp

V = sphere.center - cone.apex_location
a = dotProduct(V, cone.direction_normal)
p = a * cone_sin
q = cone_cos * cone_cos * dotProduct(V, V) - a*a
r = q - sphere_radius * sphere_radius

if ((p < sphere_radius) || (q > 0)) {
	if (r < 2 * sphere_radius * p)
		return -1; // Sphere and cone enveloppes intersect
	else if (q < 0)
		return 1; // Sphere is totally included in cone
	else
		return 0; // Shere and cone don't intersect at all
}
else {
	if ( -r < 2 * sphere_radius * p)
		return -1; // Shpere and cone enveloppes intersect
	else if (q < 0)
		return 1; // Sphere is totally included in cone
	else
		return 0; // Sphere and cone don't intersect at all
}