def sample(self, it, sampler, active=True):
bs = BSDFSample.zeros_like(it.p)
spectrum = torch.zeros_like(it.p)
cos_theta_i = it.wi[..., 2]
active = (cos_theta_i > 0) & active
f_i = fresnel(cos_theta_i, self.eta)[0]
spec_sample_weight = self.spec_sample_weight()
p_spec = f_i * spec_sample_weight
p_diff = (1 - f_i) * (1 - spec_sample_weight)
p_spec = (p_spec) / (p_spec + p_diff)
p_diff = 1 - p_spec
sample_spec = active & (sampler.sample(p_spec.shape) < p_spec)
# sample_diff = active & (~sample_spec)
bs.wo = torch.where(
sample_spec.unsqueeze(-1),
reflect(it.frame[..., 2], it.wi),
square_to_cos_hemisphere(
sampler.sample(it.shape()[:-1] + (2, ), device=it.device())),
)
bs.pdf = torch.where(
sample_spec,
p_spec,
p_diff * square_to_cos_hemisphere_pdf(bs.wo),
).clamp(min=1e-10)
f_o = fresnel(bs.wo[..., 2], self.eta)[0]
spectrum = torch.where(
sample_spec.unsqueeze(-1),
self.specular * (f_i/bs.pdf).unsqueeze(-1),
self.diffuse.expand_as(it.p) / (1- self.fdr_int) \
* bs.pdf.unsqueeze(-1) * self.inv_eta_2 *\
(1 - f_i.unsqueeze(-1)) * (1 - f_o.unsqueeze(-1))
)
return bs, spectrum
def sample(self, it, sampler, active=True):
cos_theta_i = it.wi[..., 2]
bs = BSDFSample.zeros_like(it.p)
bs.wo = square_to_cos_hemisphere(
sampler.sample(it.shape()[:-1] + (2, ), device=it.device()))
bs.wo = F.normalize(bs.wo, dim=-1)
bs.pdf = square_to_cos_hemisphere_pdf(bs.wo)
bs.eta = 1.0
spectrum = self.act(self.mlp(param_rusin2(it.wi, bs.wo)))
return bs, spectrum
def eval_and_pdf(self, it, wo, active=True):
cos_theta_i = it.wi[..., 2]
cos_theta_o = wo[..., 2]
#active = (cos_theta_i > 0) & (cos_theta_o > 0) & active
spectrum = self.preproc(cos_theta_o.unsqueeze(-1) * self.reflectance)
#spectrum[~active] = 0
pdf = square_to_cos_hemisphere_pdf(wo)
#pdf[~active] = 0
return spectrum, pdf
def eval_and_pdf(self, it, wo, active=True):
cos_theta_i = it.wi[..., 2]
cos_theta_o = wo[..., 2]
# active = (cos_theta_i > 0) & (cos_theta_o > 0) & active
R = reflect(it.frame[..., 2], it.wi)
spectral = (R * wo).sum(dim=-1).clamp(min=1e-20).pow(self.min_spec +
self.shine.exp())
spectrum = cos_theta_i.unsqueeze(-1) * self.diffuse/math.pi + \
spectral.unsqueeze(-1) * self.specular/math.pi
# just a guess of the PDF since it's not physically based
pdf = square_to_cos_hemisphere_pdf(wo)
#spectrum[~active] = 0
#pdf[~active] = 0
return spectrum, pdf
def sample(self, it, sampler, active=True):
cos_theta_i = it.wi[..., 2]
bs = BSDFSample.zeros_like(it.p)
active = (cos_theta_i > 0) & active
if not active.any(): return bs, torch.zeros_like(it.p)
bs.wo = square_to_cos_hemisphere(
sampler.sample(it.shape()[:-1] + (2, ), device=it.device()))
bs.wo = F.normalize(bs.wo, dim=-1)
bs.pdf = square_to_cos_hemisphere_pdf(bs.wo)
bs.eta = 1.0
bs.sampled_component = 0
# cast spectrum to same shape as interaction
spectrum = self.preproc(self.reflectance).expand(*it.shape()).clone()
#spectrum[(~active) | (bs.pdf <= 0), :] = 0
return bs, spectrum
def eval_and_pdf(self, it, wo, active=True):
cos_theta_i = it.wi[..., 2]
cos_theta_o = wo[..., 2]
active = (cos_theta_i > 0) & (cos_theta_o > 0) & active
f_i = fresnel(cos_theta_i, self.eta)[0]
f_o = fresnel(cos_theta_o, self.eta)[0]
pdf = square_to_cos_hemisphere_pdf(wo)
spectrum = (self.diffuse.expand_as(it.p)/(1 - self.fdr_int)) \
* self.inv_eta_2 * (pdf * (1 - f_i) * (1 - f_o)).unsqueeze(-1)
# DeltaReflection
ssw = self.spec_sample_weight()
prob_specular = ssw * f_i
prob_diffuse = (1 - f_i) * (1 - ssw)
prob_diffuse = prob_diffuse / (prob_specular + prob_diffuse)
pdf = pdf * prob_diffuse
#spectrum[~active] = 0
#pdf[~active] = 0
return spectrum, pdf
def sample(self, it, sampler, active=True):
cos_theta_i = it.wi[..., 2]
bs = BSDFSample.zeros_like(it.p)
active = (cos_theta_i > 0) & active
if not active.any(): return bs, torch.zeros_like(it.p)
bs.wo = square_to_cos_hemisphere(
sampler.sample(it.shape()[:-1] + (2, ), device=it.device()))
bs.pdf = square_to_cos_hemisphere_pdf(bs.wo)
bs.eta = 1.0
bs.sampled_component = 0
# cast spectrum to same shape as interaction
cos_theta_o = bs.wo[..., 2]
active = (cos_theta_o > 0) & active
R = reflect(it.frame[..., 2], it.wi)
spectral = (R * bs.wo).sum(dim=-1).clamp(
min=1e-20).pow(self.min_spec + self.shine.exp())
spectrum = cos_theta_i.unsqueeze(-1) * self.diffuse/math.pi + \
spectral.unsqueeze(-1) * self.specular/math.pi
spectrum[(~active) | (bs.pdf <= 0), :] = 0
return bs, spectrum