Float *computeTransmittance(const char *name, Float ior, Float alpha,
size_t resolution, Float &diffTrans, int inverted) {
Properties bsdfProps(alpha == 0 ? "dielectric" : "roughdielectric");
if (inverted) {
bsdfProps.setFloat("intIOR", 1.00);
bsdfProps.setFloat("extIOR", ior);
} else {
bsdfProps.setFloat("extIOR", 1.00);
bsdfProps.setFloat("intIOR", ior);
}
bsdfProps.setFloat("alpha", alpha);
bsdfProps.setString("distribution", name);
ref<BSDF> bsdf = static_cast<BSDF *>(
PluginManager::getInstance()->createObject(bsdfProps));
Float stepSize = 1.0f / (resolution-1);
Float error;
NDIntegrator intTransmittance(1, 2, 50000, 0, 1e-6f);
NDIntegrator intDiffTransmittance(1, 1, 50000, 0, 1e-6f);
Float *transmittances = new Float[resolution];
for (size_t i=0; i<resolution; ++i) {
Float t = i * stepSize;
if (i == 0) /* Don't go all the way to zero */
t = stepSize/10;
Float cosTheta = std::pow(t, (Float) 4.0f);
Vector wi(std::sqrt(std::max((Float) 0,
1-cosTheta*cosTheta)), 0, cosTheta);
Float min[2] = {0, 0}, max[2] = {1, 1};
intTransmittance.integrateVectorized(
boost::bind(&transmittanceIntegrand, bsdf, wi, _1, _2, _3),
min, max, &transmittances[i], &error, NULL);
}
Float min[1] = { 0 }, max[1] = { 1 };
intDiffTransmittance.integrateVectorized(
boost::bind(&diffTransmittanceIntegrand, transmittances, resolution, _1, _2, _3),
min, max, &diffTrans, &error, NULL);
if (alpha == 0.0f)
cout << diffTrans << " vs " << 1-fresnelDiffuseReflectance(inverted ? (1.0f / ior) : ior) << endl;
return transmittances;
}
Float computeDiffuseTransmittance(const char *name, Float eta, Float alpha, size_t resolution = 100) {
Properties bsdfProps("roughdielectric");
if (eta < 1) {
bsdfProps.setFloat("intIOR", 1.0f);
bsdfProps.setFloat("extIOR", 1.0f / eta);
} else {
bsdfProps.setFloat("extIOR", 1.0f);
bsdfProps.setFloat("intIOR", eta);
}
bsdfProps.setFloat("alpha", alpha);
bsdfProps.setString("distribution", name);
ref<BSDF> bsdf = static_cast<BSDF *>(
PluginManager::getInstance()->createObject(bsdfProps));
Float *transmittances = new Float[resolution];
Float stepSize = 1.0f / (resolution-1);
Float error;
NDIntegrator intTransmittance(1, 2, 50000, 0, 1e-6f);
NDIntegrator intDiffTransmittance(1, 1, 50000, 0, 1e-6f);
for (size_t i=0; i<resolution; ++i) {
Float cosTheta = stepSize * i;
Vector wi(math::safe_sqrt(1-cosTheta*cosTheta), 0, cosTheta);
Float min[2] = {0, 0}, max[2] = {1, 1};
intTransmittance.integrateVectorized(
boost::bind(&transmittanceIntegrand, bsdf, wi, _1, _2, _3),
min, max, &transmittances[i], &error, NULL);
}
Float Fdr;
Float min[1] = { 0 }, max[1] = { 1 };
intDiffTransmittance.integrateVectorized(
boost::bind(&diffTransmittanceIntegrand, transmittances, resolution, _1, _2, _3),
min, max, &Fdr, &error, NULL);
delete[] transmittances;
return Fdr;
}
