def follow(ray: Ray, scene: Scene, max_iters=1000, renderer=None) -> [Tuple[Ray, Decision]]:
""" Follow the ray through a scene.
This the highest level ray-tracing function. It moves the ray through the
scene and returns a list of rays a Monte Carlo decision events. Each decision
is an interaction which alters one of the rays properties such as position,
direction or wavelength.
Raises
------
TraceError
If an error occurred while tracing.
Returns
-------
List of (Ray, Decision) tuples.
"""
path = [(ray, Decision.EMIT)]
idx = 0
last_ray = ray
while ray.is_alive:
intersections = scene.intersections(ray.position, ray.direction)
points, nodes = zip(*[(x.point, x.hit) for x in intersections])
for ray, decision in step(ray, points, nodes, renderer=renderer):
path.append((ray, decision))
if points_equal(ray.position, last_ray.position) and np.allclose(ray.direction, last_ray.direction):
raise TraceError("Ray did not move.")
last_ray = ray
if idx > max_iters:
raise TraceError("Ray got stuck.")
return path
def test_intersection(self):
root = Node(name='Root')
a = Node(name="A", parent=root)
b = Node(name="B", parent=a)
b.geometry = Sphere(radius=1.0)
a.translate((1.0, 0.0, 0.0))
loc = (-2.0, 0.0, 0.0)
vec = (1.0, 0.0, 0.0)
scene = Scene(root=root)
intersections = scene.intersections(loc, vec)
points = tuple([x.point for x in intersections])
# In frame of a everything is shifed 1 along x
assert points == ((0.0, 0.0, 0.0), (2.0, 0.0, 0.0))
def test_intersection(self):
root = Node(name='Root')
a = Node(name="A", parent=root)
b = Node(name="B", parent=a)
b.geometry = Sphere(radius=1.0)
a.translate((1.0, 0.0, 0.0))
loc = (-2.0, 0.0, 0.0)
vec = (1.0, 0.0, 0.0)
scene = Scene(root=root)
intersections = scene.intersections(loc, vec)
points = tuple([x.point for x in intersections])
# In frame of a everything is shifed 1 along x
assert points == ((0.0, 0.0, 0.0), (2.0, 0.0, 0.0))
def test_intersection_with_rotation_around_z(self):
root = Node(name='Root')
a = Node(name="A", parent=root)
b = Node(name="B", parent=a)
b.geometry = Sphere(radius=1.0)
a.translate((1.0, 0.0, 0.0))
# This rotation make an z translation in b becomes a -y translation in a
a.rotate(np.pi / 2, axis=(0.0, 0.0, 1.0))
loc = (-2.0, 0.0, 0.0)
vec = (1.0, 0.0, 0.0)
scene = Scene(root=root)
intersections = scene.intersections(loc, vec)
points = tuple([x.point for x in intersections])
assert np.allclose(points, ((0.0, 0.0, 0.0), (2.0, 0.0, 0.0)))
def test_intersection_with_rotation_around_x(self):
root = Node(name='Root')
a = Node(name="A", parent=root)
b = Node(name="B", parent=a)
b.geometry = Sphere(radius=1.0)
b.translate((1.0, 0.0, 0.0))
# Rotation around x therefore no displace in x
b.rotate(np.pi / 2, (1.0, 0.0, 0.0))
loc = (-2.0, 0.0, 0.0)
vec = (1.0, 0.0, 0.0)
scene = Scene(root=root)
intersections = scene.intersections(loc, vec)
points = tuple([x.point for x in intersections])
assert points == ((0.0, 0.0, 0.0), (2.0, 0.0, 0.0))
def test_intersection_with_rotation_around_z(self):
root = Node(name='Root')
a = Node(name="A", parent=root)
b = Node(name="B", parent=a)
b.geometry = Sphere(radius=1.0)
a.translate((1.0, 0.0, 0.0))
# This rotation make an z translation in b becomes a -y translation in a
a.rotate(np.pi/2, axis=(0.0, 0.0, 1.0))
loc = (-2.0, 0.0, 0.0)
vec = (1.0, 0.0, 0.0)
scene = Scene(root=root)
intersections = scene.intersections(loc, vec)
points = tuple([x.point for x in intersections])
assert np.allclose(points, ((0.0, 0.0, 0.0), (2.0, 0.0, 0.0)))
def test_intersection_with_rotation_around_x(self):
root = Node(name='Root')
a = Node(name="A", parent=root)
b = Node(name="B", parent=a)
b.geometry = Sphere(radius=1.0)
b.translate((1.0, 0.0, 0.0))
# Rotation around x therefore no displace in x
b.rotate(np.pi/2, (1.0, 0.0, 0.0))
loc = (-2.0, 0.0, 0.0)
vec = (1.0, 0.0, 0.0)
scene = Scene(root=root)
intersections = scene.intersections(loc, vec)
points = tuple([x.point for x in intersections])
assert points == ((0.0, 0.0, 0.0), (2.0, 0.0, 0.0))
def test_intersection_coordinate_system(self):
root = Node(name="Root", geometry=Sphere(radius=10.0))
a = Node(name="A", parent=root, geometry=Sphere(radius=1.0))
a.translate((1.0, 0.0, 0.0))
scene = Scene(root)
initial_ray = Ray(
position=(-2.0, 0.0, 0.0),
direction=(1.0, 0.0, 0.0),
wavelength=None,
is_alive=True,
)
scene_intersections = scene.intersections(initial_ray.position,
initial_ray.direction)
a_intersections = tuple(map(lambda x: x.to(root), scene_intersections))
assert scene_intersections == a_intersections
def test_intersection_coordinate_system(self):
root = Node(name="Root", geometry=Sphere(radius=10.0))
a = Node(name="A", parent=root, geometry=Sphere(radius=1.0))
a.translate((1.0, 0.0, 0.0))
scene = Scene(root)
initial_ray = Ray(
position=(-2.0, 0.0, 0.0),
direction=(1.0, 0.0, 0.0),
wavelength=None,
is_alive=True,
)
scene_intersections = scene.intersections(
initial_ray.position,
initial_ray.direction
)
a_intersections = tuple(map(lambda x: x.to(root), scene_intersections))
assert scene_intersections == a_intersections