RGB SpotLight::Sample_L(const Point &p, Float pEpsilon, const LightSample &ls,
Vector3f *wi, Float *pdf, VisibilityTester *vis) const {
*wi = Normalize(mPos - p); //标准化的点到光源的向量
*pdf = 1.0f;
vis->SetSegment(p, pEpsilon, mPos, 0.0f);
return mIntensity * Falloff(-*wi) / DistanceSqr(mPos, p);
}
Spectrum SpotLight::Sample_L(const Scene *scene, const LightSample &ls,
float u1, float u2, float time, Ray *ray, Normal *Ns, float *pdf) const {
Vector v = UniformSampleCone(ls.uPos[0], ls.uPos[1], cosTotalWidth);
*ray = Ray(lightPos, LightToWorld(v), 0.f, INFINITY, time);
*Ns = (Normal)ray->d;
*pdf = UniformConePdf(cosTotalWidth);
return Intensity * Falloff(ray->d);
}
Spectrum SpotLight::Sample_L(const Point &p, float pEpsilon,
const LightSample &ls, float time, Vector *wi,
float *pdf, VisibilityTester *visibility) const {
*wi = Normalize(lightPos - p);
*pdf = 1.f;
visibility->SetSegment(p, pEpsilon, lightPos, 0., time);
return Intensity * Falloff(-*wi) / DistanceSquared(lightPos, p);
}
Spectrum SpotLight::Sample_Li(const Interaction &ref, const Point2f &u,
Vector3f *wi, Float *pdf,
VisibilityTester *vis) const {
*wi = Normalize(pLight - ref.p);
*pdf = 1.f;
*vis = VisibilityTester(ref, Interaction(pLight, ref.time, medium));
return intensity * Falloff(-*wi) / DistanceSquared(pLight, ref.p);
}
Spectrum SpotLight::Sample_Le(const Point2f &u1, const Point2f &u2, Float time,
Ray *ray, Normal3f *nLight, Float *pdfPos,
Float *pdfDir) const {
Vector3f w = UniformSampleCone(u1, cosTotalWidth);
*ray = Ray(pLight, LightToWorld(w), Infinity, time, mediumInterface.inside);
*nLight = (Normal3f)ray->d;
*pdfPos = 1;
*pdfDir = UniformConePdf(cosTotalWidth);
return I * Falloff(ray->d);
}
void samplePhoton(Sampler *sampler, Photon &photon, int N, int nLights, Vector3f &unQuantDir) const {
const Point2f ls2 = sampler->next2D();
const Point3f pos = m_position;
//get a direction
const Vector3f cosDir = Warp::squareToUniformSphereCap(ls2, m_theta);
// transform it to world coordinates
Frame globalFrame = Frame(m_direction);
const Vector3f dir = globalFrame.toWorld(cosDir);
unQuantDir = dir;
const Color3f power = (Falloff(dir) * Power() * float(nLights)) / (float(N));
// create the photon
photon = Photon(pos, dir, power);
}
Color3f sampleL(Point3f &p,
float pEpsilon,
const Point2f &ls, /*float time,*/
Vector3f *wi,
float *pdf,
VisibilityTester *vis) const {
//set the direction to the light
*wi = (m_position - p).normalized();
//pdf i one, because it is a point light
*pdf = 1.f;
if(wi->dot(m_direction) > m_theta)
*pdf = 0.0f;
//init the visibility tester
vis->SetSegment(p, pEpsilon, m_position, 0.0f);
// calc dist squared between m_position and p
float distSquared = (m_position - p).squaredNorm();
//retrun the power divided squared distance and four pi
return Falloff(- *wi) * m_intensity / (distSquared);
}
