cv::Vec3f BlinnMaterial::brdf(const HitRecord &hit, QVector3D direction) const
{
QVector3D normal = hit.getSurfaceNormal();
normal.normalize();
QVector3D wo = -hit.getRay().getDirection().normalized();
QVector3D wi = -direction.normalized();
if(signum(QVector3D::dotProduct(normal, wo)) != signum(QVector3D::dotProduct(normal, wi)))
{
return cv::Vec3f();
}
if(QVector3D::dotProduct(normal, wo) < 0) normal *= -1;
QVector3D wh = wi + wo;
wh.normalize();
return kd * (1 / M_PI) + ks * D(wh, normal) * G(wi, wo, normal) / (4 * QVector3D::dotProduct(wo, normal) * QVector3D::dotProduct(wi, normal));
}
QVector3D BlinnMaterial::outDirection(const HitRecord &hit, Sample s, float &pdf, cv::Vec3f &brdf) const
{
QVector3D normal = hit.getSurfaceNormal();
normal.normalize();
QVector3D wo = -hit.getRay().getDirection().normalized();
if(QVector3D::dotProduct(normal, wo) < 0) normal *= -1;
QVector3D wh = s.getCosinePowerWeightedDirection(normal, pdf, exponent);
if(QVector3D::dotProduct(wo, wh) < 0)
{
pdf = 0;
brdf = cv::Vec3f();
return QVector3D();
}
//if(QVector3D::dotProduct(wh, normal) < 0) wh *= -1;
QVector3D out = -reflect(wo, wh);
assert(pdf >= 0);
pdf /= 4 * std::max(QVector3D::dotProduct(wo, wh), .0001f);
assert(pdf >= 0);
brdf = this->brdf(hit, out);
assert(brdf[0] >= 0 && brdf[1] >= 0 && brdf[2] >= 0);
return out;
}
Path Renderer::createPath(const Ray& primaryRay, const Intersectable &scene, const Sample pathSamples[], cv::Vec3f alpha, int pathLength, float russianRoulettePdf, int russianRouletteStartIndex)
{
Path result;
HitRecord hit = scene.intersect(primaryRay);
for(int i = 0; i < pathLength; i++)
{
if(!hit.intersects()) return result;
float pdf;
cv::Vec3f brdf;
QVector3D outDirection = hit.getMaterial().outDirection(hit, pathSamples[i], pdf, brdf);
if(hit.getMaterial().emitsLight())
{
result.alphaValues.push_back(alpha);
result.hitRecords.push_back(hit);
return result;
}
else if(hit.getMaterial().isSpecular())
{
//Try not to terminate on refractive vertices
if(i == pathLength - 1 && pathLength < MAX_DEPTH) pathLength++;
}
else
{
result.alphaValues.push_back(alpha);
result.hitRecords.push_back(hit);
if(pdf == 0 || alpha == cv::Vec3f()) return result;
float cos = fabs(QVector3D::dotProduct(outDirection.normalized(), hit.getSurfaceNormal().normalized()));
assert(cos >= 0 && !isnan(pdf));
assert(pdf > 0 && !isnan(pdf));
alpha = alpha.mul(brdf) * (cos / pdf);
if(i > russianRouletteStartIndex) alpha *= (1 / russianRoulettePdf);
}
hit = scene.intersect(Ray(hit.getIntersectingPoint(), outDirection));
}
return result;
}
