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
def Li(self, scene, renderer, ray, intersection, sample, rng):
"""Computes the radiance along a ray."""
return Spectrum(1.0)
L = Spectrum(0.0)
# evaluate BSDF at hit point
bsdf = intersection.get_bsdf(ray)
# initialize common variables for Whitted integrator
p = bsdf.dg_shading.p
n = bsdf.dg_shading.nn
wo = -ray.d
# compute emitted light if ray hit an area light source
L += intersection.Le(wo)
# add contribution of each light source
for light in self.scene.lights:
light_sample = LightSample.from_rng(rng)
Li, wi, pdf, visibility = light.sample_L(p,
intersection.ray_epsilon,
light_sample,
ray.time)
if Li.is_black() or pdf == 0.0:
continue
f = bsdf.f(wo, wi)
if (not f.is_black()) and visibility.unoccluded(scene):
L+= f * Li * abs_dot(wi, n) * visibility.transmittance(scene,
renderer,
sample,
rng) / pdf
if ray.depth+1 < self.max_depth:
# trace rays for specular reflection and refraction
L += specular_reflect(ray, bsdf, rng, intersection,
renderer, scene, sample)
L+= specular_transmit(ray, bsdf, rng, intersection,
renderer, scene, sample)
return L
def Li(self, scene, renderer, ray, intersection, sample, rng):
"""Computes the radiance along a ray."""
return Spectrum(1.0)
L = Spectrum(0.0)
# evaluate BSDF at hit point
bsdf = intersection.get_bsdf(ray)
# initialize common variables for Whitted integrator
p = bsdf.dg_shading.p
n = bsdf.dg_shading.nn
wo = -ray.d
# compute emitted light if ray hit an area light source
L += intersection.Le(wo)
# add contribution of each light source
for light in self.scene.lights:
light_sample = LightSample.from_rng(rng)
Li, wi, pdf, visibility = light.sample_L(p,
intersection.ray_epsilon,
light_sample, ray.time)
if Li.is_black() or pdf == 0.0:
continue
f = bsdf.f(wo, wi)
if (not f.is_black()) and visibility.unoccluded(scene):
L += f * Li * abs_dot(wi, n) * visibility.transmittance(
scene, renderer, sample, rng) / pdf
if ray.depth + 1 < self.max_depth:
# trace rays for specular reflection and refraction
L += specular_reflect(ray, bsdf, rng, intersection, renderer,
scene, sample)
L += specular_transmit(ray, bsdf, rng, intersection, renderer,
scene, sample)
return L
