def path_push(path: Path, ray: Ray):
# update stuff appropriately
if path.direction == Direction.STORAGE.value:
# don't change anything, this is just a stack. this reduces wasted calculation and preserves first-vertex values
pass
elif path.ray is None:
# this shouldn't come up
pass
else:
G = geometry_term(path.ray, ray)
path.ray.direction = unit(ray.origin - path.ray.origin)
if path.ray.prev is None:
# pushing onto stack of 1, just propagate p and color (?)
ray.color = path.ray.color * G
ray.p = path.ray.p * G
else:
# pushing onto stack of 2 or more, do some work
brdf = BRDF_function(path.ray.material, -1 * path.ray.prev.direction, path.ray.normal, path.ray.direction,
path.direction)
ray.color = path.ray.local_color * path.ray.color * brdf * G
ray.p = path.ray.p * G * BRDF_pdf(path.ray.material, -1 * path.ray.prev.direction, path.ray.normal, path.ray.direction,
path.direction)
ray.bounces = path.ray.bounces + 1
# store new ray
ray.prev = path.ray
path.ray = ray
def extend_path(path, root, path_direction):
for i in range(MAX_BOUNCES):
ray = path[-1]
triangle, t = traverse_bvh(root, ray)
if triangle is not None:
# generate new ray
# new vectors
origin = ray.origin + ray.direction * t
direction = BRDF_sample(triangle.material, -1 * ray.direction,
triangle.normal, path_direction)
new_ray = Ray(origin, direction)
# store info from triangle
new_ray.normal = triangle.normal
new_ray.material = triangle.material
new_ray.local_color = triangle.color
if path_direction == Direction.FROM_CAMERA.value and triangle.emitter:
new_ray.hit_light = True
# probability, weight, and color updates
G = geometry_term(ray, new_ray)
if i == 0:
# only need to multiply by G because p of this direction is already stored at creation
new_ray.p = ray.p * G
# same deal, "brdf" of source is already in ray.color
new_ray.color = ray.color * G
new_ray.G = G
else:
# so the idea here is that each vertex has information about everything up to it but not including it,
# because we can't be sure of anything about the final bounce until we know the joining vertex
bounce_p = BRDF_pdf(ray.material, -1 * path[-2].direction,
ray.normal, ray.direction, path_direction)
new_ray.p = ray.p * G * bounce_p
new_ray.color = ray.color * ray.local_color * G * BRDF_function(
ray.material, -1 * path[-2].direction, ray.normal,
ray.direction, path_direction)
new_ray.G = G
ray.local_p = bounce_p
path.append(new_ray)
else:
break
def generate_light_ray(box: Box):
light_index = np.random.randint(0, len(box.lights))
light = box.lights[light_index]
light_origin = light.sample_surface()
x, y, z = local_orthonormal_system(light.normal)
light_direction = random_hemisphere_uniform_weighted(x, y, z)
ray = Ray(light_origin, light_direction)
ray.color = light.color
ray.local_color = light.color
ray.normal = light.normal
ray.p = 1 / (2 * np.pi * light.surface_area)
return ray
def path_push(path: Path, ray: Ray):
# update stuff appropriately
G = geometry_term(path.ray, ray)
path.ray.direction = unit(ray.origin - path.ray.origin)
if path.ray.prev is None:
# pushing onto stack of 1, just propagate p and color (?)
ray.color = path.ray.color * G
ray.p = path.ray.p * G
else:
# pushing onto stack of 2 or more, do some work
brdf = brdf_function(path.ray.material, -1 * path.ray.prev.direction,
path.ray.normal, path.ray.direction,
path.direction)
ray.color = path.ray.local_color * path.ray.color * brdf * G
ray.p = path.ray.p * G * brdf_pdf(
path.ray.material, -1 * path.ray.prev.direction, path.ray.normal,
path.ray.direction, path.direction)
ray.bounces = path.ray.bounces + 1
# store new ray
ray.prev = path.ray
path.ray = ray
def generate_light_ray(emitters):
light = emitters[np.random.randint(0, len(emitters))]
light_origin = light.sample_surface()
x, y, z = local_orthonormal_system(light.normal)
light_direction = random_hemisphere_uniform_weighted(x, y, z)
ray = Ray(light_origin, light_direction)
ray.color = light.color
ray.local_color = light.color
ray.normal = light.normal
# this seems made up
ray.p = 1 / (2 * np.pi * light.surface_area)
return ray