def sample_p(self, p, u1, u2):
"""Sample at point p."""
# Compute coordinate system for sphere sampling
p_center = self.object_to_world(Point(0, 0, 0))
wc = normalize(p_center - p)
wc_x, wc_y = coordinate_system(wc)
# Sample uniformly on sphere if $\pt{}$ is inside it
if (distance_squared(p, p_center) - self.radius * self.radius) < 1e-4:
return self.sample(u1, u2)
# Sample sphere uniformly inside subtended cone
sin_theta_max2 = self.radius * self.radius / distance_squared(
p, p_center)
cos_theta_max = math.sqrt(max(0.0, 1.0 - sin_theta_max2))
raise Exception("next_line")
# r = Ray(p, uniform_sample_cone(u1, u2, cos_theta_max, wcX, wcY, wc), 1e-3)
r = Ray(p)
intersect, t_hit, ray_epsilon, dg_sphere = self.intersect(r)
if not intersect:
t_hit = dot(p_center - p, normalize(r.d))
ps = r(t_hit)
ns = Normal(normalize(ps - p_center))
if (self.reverse_orientation):
ns *= -1.0
return ps, ns
def sample_p(self, p, u1, u2):
"""Sample at point p."""
# Compute coordinate system for sphere sampling
p_center = self.object_to_world(Point(0, 0, 0))
wc = normalize(p_center - p)
wc_x, wc_y = coordinate_system(wc)
# Sample uniformly on sphere if $\pt{}$ is inside it
if (distance_squared(p, p_center) - self.radius * self.radius) < 1e-4:
return self.sample(u1, u2)
# Sample sphere uniformly inside subtended cone
sin_theta_max2 = self.radius * self.radius / distance_squared(p, p_center)
cos_theta_max = math.sqrt(max(0.0, 1.0 - sin_theta_max2))
raise Exception("next_line")
# r = Ray(p, uniform_sample_cone(u1, u2, cos_theta_max, wcX, wcY, wc), 1e-3)
r = Ray(p)
intersect, t_hit, ray_epsilon, dg_sphere = self.intersect(r)
if not intersect:
t_hit = dot(p_center - p, normalize(r.d))
ps = r(t_hit)
ns = Normal(normalize(ps - p_center))
if self.reverse_orientation:
ns *= -1.0
return ps, ns
def pdf_wi(self, p, wi):
"""Intersect sample ray with area light geometry."""
p_center = self.object_to_world(Point(0, 0, 0))
# Return uniform weight if point inside sphere
if (distance_squared(p, p_center) - self.radius * self.radius) < 1e-4:
return Shape.pdf_wi(self, p, wi)
# Compute general sphere weight
sin_theta_max2 = self.radius * self.radius / distance_squared(p, p_center)
cos_theta_max = math.sqrt(max(0.0, 1.0 - sin_theta_max2))
raise Exception("next_line")
# return uniform_cone_pdf(cos_theta_max)
return 0.0
def pdf_wi(self, p, wi):
"""Intersect sample ray with area light geometry."""
p_center = self.object_to_world(Point(0, 0, 0))
# Return uniform weight if point inside sphere
if (distance_squared(p, p_center) - self.radius * self.radius) < 1e-4:
return Shape.pdf_wi(self, p, wi)
# Compute general sphere weight
sin_theta_max2 = self.radius * self.radius / distance_squared(
p, p_center)
cos_theta_max = math.sqrt(max(0.0, 1.0 - sin_theta_max2))
raise Exception("next_line")
# return uniform_cone_pdf(cos_theta_max)
return 0.0
def pdf_wi(self, p, wi):
"""Intersect sample ray with area light geometry."""
dg_light = DifferentialGeometry()
ray = Ray(p, wi, 1e-3)
ray.depth = -1 # temp hack to ignore alpha mask
intersect, t_hit, ray_epsilon, dg_light = self.intersect(ray)
if not intersect:
return 0.0
# convert light sample weight to solid angle measure
pdf = distance_squared(p, ray(t_hit)) / \
(abs_dot(dg_light.nnm -wi) * self.area())
if pdf == float('inf'):
return 0.0
return pdf