def intersect(self, r: Ray):
ray2 = r.transform(self.transform.inverse())
sphere_to_ray = ray2.origin - point(0, 0, 0)
a = ray2.direction.dot(ray2.direction)
b = 2 * ray2.direction.dot(sphere_to_ray)
c = sphere_to_ray.dot(sphere_to_ray) - 1
delta = b * b - 4 * a * c
if delta < 0:
return []
t1 = (-b - sqrt(delta)) / (2 * a)
t2 = (-b + sqrt(delta)) / (2 * a)
i1 = intersections.Intersection(t1, self)
i2 = intersections.Intersection(t2, self)
return [i1, i2]
def test_scaling_ray(self):
r = Ray(point(1, 2, 3), vector(0, 1, 0))
m = scaling(2, 3, 4)
r2 = r.transform(m)
self.assertEqual(point(2, 6, 12), r2.origin)
self.assertEqual(vector(0, 3, 0), r2.direction)
def test_translating_ray(self):
r = Ray(point(1, 2, 3), vector(0, 1, 0))
m = translation(3, 4, 5)
r2 = r.transform(m)
self.assertEqual(point(4, 6, 8), r2.origin)
self.assertEqual(vector(0, 1, 0), r2.direction)