def test_transformed_group():
g = Group()
g.set_transform(Scaling(2, 2, 2))
s = Sphere()
s.set_transform(Translation(5, 0, 0))
g.add_child(s)
r = Ray(Point(10, 0, -10), Vector(0, 0, 1))
xs = g.intersect(r)
assert len(xs) == 2
def test_world_to_object():
g1 = Group()
g1.set_transform(RotationY(math.pi / 2))
g2 = Group()
g2.set_transform(Scaling(2, 2, 2))
g1.add_child(g2)
s = Sphere()
s.set_transform(Translation(5, 0, 0))
g2.add_child(s)
p = s.world_to_object(Point(-2, 0, -10))
assert p == Point(0, 0, -1)
def test_child_normal():
g1 = Group()
g1.set_transform(RotationY(math.pi / 2))
g2 = Group()
g2.set_transform(Scaling(1, 2, 3))
g1.add_child(g2)
s = Sphere()
s.set_transform(Translation(5, 0, 0))
g2.add_child(s)
n = s.normal_at(Point(1.7321, 1.1547, -5.5774))
assert n == Vector(0.2857, 0.4286, -0.8571)
def test_normal_object_to_world():
g1 = Group()
g1.set_transform(RotationY(math.pi / 2))
g2 = Group()
g2.set_transform(Scaling(1, 2, 3))
g1.add_child(g2)
s = Sphere()
s.set_transform(Translation(5, 0, 0))
g2.add_child(s)
n = s.normal_to_world(
Vector(math.sqrt(3) / 3,
math.sqrt(3) / 3,
math.sqrt(3) / 3))
assert n == Vector(0.2857, 0.4286, -0.8571)