Spectrum sampleRay(Ray &ray, const Point2 &pixelSample,
const Point2 &otherSample, Float timeSample) const {
Point2 tmp = warp::squareToUniformDiskConcentric(otherSample)
* m_apertureRadius;
ray.time = sampleTime(timeSample);
/* Compute the corresponding position on the
near plane (in local camera space) */
Point nearP = m_sampleToCamera(Point(
pixelSample.x * m_invResolution.x,
pixelSample.y * m_invResolution.y, 0.0f));
/* Aperture position */
Point apertureP(tmp.x, tmp.y, 0.0f);
/* Sampled position on the focal plane */
Point focusP = nearP * (m_focusDistance / nearP.z);
/* Turn these into a normalized ray direction, and
adjust the ray interval accordingly */
Vector d = normalize(focusP - apertureP);
Float invZ = 1.0f / d.z;
ray.mint = m_nearClip * invZ;
ray.maxt = m_farClip * invZ;
const Transform &trafo = m_worldTransform->eval(ray.time);
ray.setOrigin(trafo.transformAffine(apertureP));
ray.setDirection(trafo(d));
return Spectrum(1.0f);
}
Spectrum sampleRayDifferential(RayDifferential &ray, const Point2 &pixelSample,
const Point2 &otherSample, Float timeSample) const {
/* Record pixel index, added by Lifan */
ray.index.x = (int)std::floor(pixelSample.x);
ray.index.y = (int)std::floor(pixelSample.y);
Point2 tmp = warp::squareToUniformDiskConcentric(otherSample)
* m_apertureRadius;
ray.time = sampleTime(timeSample);
/* Compute the corresponding position on the
near plane (in local camera space) */
Point nearP = m_sampleToCamera(Point(
pixelSample.x * m_invResolution.x,
pixelSample.y * m_invResolution.y, 0.0f));
/* Aperture position */
Point apertureP(tmp.x, tmp.y, 0.0f);
/* Sampled position on the focal plane */
Float fDist = m_focusDistance / nearP.z;
Point focusP = nearP * fDist;
Point focusPx = (nearP+m_dx) * fDist;
Point focusPy = (nearP+m_dy) * fDist;
/* Turn that into a normalized ray direction, and
adjust the ray interval accordingly */
Vector d = normalize(focusP - apertureP);
Float invZ = 1.0f / d.z;
ray.mint = m_nearClip * invZ;
ray.maxt = m_farClip * invZ;
const Transform &trafo = m_worldTransform->eval(ray.time);
ray.setOrigin(trafo.transformAffine(apertureP));
ray.setDirection(trafo(d));
ray.rxOrigin = ray.ryOrigin = ray.o;
ray.rxDirection = trafo(normalize(Vector(focusPx - apertureP)));
ray.ryDirection = trafo(normalize(Vector(focusPy - apertureP)));
ray.hasDifferentials = true;
return Spectrum(1.0f);
}
Spectrum sampleDirect(DirectSamplingRecord &dRec, const Point2 &sample) const {
const Transform &trafo = m_worldTransform->eval(dRec.time);
/* Transform the reference point into the local coordinate system */
Point refP = trafo.inverse().transformAffine(dRec.ref);
/* Check if it is outside of the clip range */
if (refP.z < m_nearClip || refP.z > m_farClip) {
dRec.pdf = 0.0f;
return Spectrum(0.0f);
}
/* Sample a position on the aperture (in local coordinates) */
Point2 tmp = warp::squareToUniformDiskConcentric(sample)
* m_apertureRadius;
Point apertureP(tmp.x, tmp.y, 0);
/* Compute the normalized direction vector from the
aperture position to the reference point */
Vector localD(refP - apertureP);
Float dist = localD.length(),
invDist = 1.0f / dist;
localD *= invDist;
Float value = importance(apertureP, localD, &dRec.uv);
if (value == 0.0f) {
dRec.pdf = 0.0f;
return Spectrum(0.0f);
}
dRec.p = trafo.transformAffine(apertureP);
dRec.d = (dRec.p - dRec.ref) * invDist;
dRec.dist = dist;
dRec.n = trafo(Vector(0.0f, 0.0f, 1.0f));
dRec.pdf = m_aperturePdf * dist*dist/(Frame::cosTheta(localD));
dRec.measure = ESolidAngle;
/* intentionally missing a cosine factor wrt. the aperture
disk (it is already accounted for in importance()) */
return Spectrum(value * invDist * invDist);
}
