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volpath_simple: fixed a minor logic error that could cause errors in light paths that simultaneously involve multiple index-matched and index-mismatched medium transitions

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Wenzel Jakob 2012-10-20 01:42:50 -04:00
parent f041cd58eb
commit 8e2bfb7340
1 changed files with 23 additions and 20 deletions
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43
src/integrators/path/volpath_simple.cpp
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@ -29,11 +29,11 @@ static StatsCounter avgPathLength("Volumetric path tracer", "Average path length
* \parameter{maxDepth}{\Integer}{Specifies the longest path depth
* in the generated output image (where \code{-1} corresponds to $\infty$).
* A value of \code{1} will only render directly visible light sources.
* \code{2} will lead to single-bounce (direct-only) illumination,
* \code{2} will lead to single-bounce (direct-only) illumination,
* and so on. \default{\code{-1}}
* }
* \parameter{rrDepth}{\Integer}{Specifies the minimum path depth, after
* which the implementation will start to use the ``russian roulette''
* \parameter{rrDepth}{\Integer}{Specifies the minimum path depth, after
* which the implementation will start to use the ``russian roulette''
* path termination criterion. \default{\code{5}}
* }
* \parameter{strictNormals}{\Boolean}{Be strict about potential
@ -51,12 +51,12 @@ static StatsCounter avgPathLength("Volumetric path tracer", "Average path length
* or one of the bidirectional techniques.
*
* \remarks{
* \item This integrator performs poorly when rendering
* \item This integrator performs poorly when rendering
* participating media that have a different index of refraction compared
* to the surrounding medium.
* \item This integrator has difficulties rendering
* scenes that contain relatively glossy materials (\pluginref{volpath} is preferable in this case).
* \item This integrator has poor convergence properties when rendering
* \item This integrator has poor convergence properties when rendering
* caustics and similar effects. In this case, \pluginref{bdpt} or
* one of the photon mappers may be preferable.
* }
@ -79,7 +79,7 @@ public:
bool scattered = false;
Float eta = 1.0f;
/* Perform the first ray intersection (or ignore if the
/* Perform the first ray intersection (or ignore if the
intersection has already been provided). */
rRec.rayIntersect(ray);
Spectrum throughput(1.0f);
@ -144,7 +144,7 @@ public:
scene->rayIntersect(ray, its);
scattered = true;
} else {
/* Sample
/* Sample
tau(x, y) * (Surface integral). This happens with probability mRec.pdfFailure
Account for this and multiply by the proper per-color-channel transmittance.
*/
@ -153,9 +153,9 @@ public:
throughput *= mRec.transmittance / mRec.pdfFailure;
if (!its.isValid()) {
/* If no intersection could be found, possibly return
/* If no intersection could be found, possibly return
attenuated radiance from a background luminaire */
if (rRec.type & RadianceQueryRecord::EEmittedRadiance)
if (rRec.type & RadianceQueryRecord::EEmittedRadiance)
Li += throughput * scene->evalEnvironment(ray);
break;
}
@ -171,17 +171,17 @@ public:
/* Prevent light leaks due to the use of shading normals */
Float wiDotGeoN = -dot(its.geoFrame.n, ray.d),
wiDotShN = Frame::cosTheta(its.wi);
if (m_strictNormals && wiDotGeoN * wiDotShN < 0)
if (m_strictNormals && wiDotGeoN * wiDotShN < 0)
break;
/* ==================================================================== */
/* Direct illumination sampling */
/* ==================================================================== */
const BSDF *bsdf = its.getBSDF(ray);
/* Estimate the direct illumination if this is requested */
if (rRec.type & RadianceQueryRecord::EDirectSurfaceRadiance &&
if (rRec.type & RadianceQueryRecord::EDirectSurfaceRadiance &&
(bsdf->getType() & BSDF::ESmooth)) {
DirectSamplingRecord dRec(its);
int maxInteractions = m_maxDepth - rRec.depth - 1;
@ -210,7 +210,7 @@ public:
/* Sample BSDF * cos(theta) */
BSDFSamplingRecord bRec(its, rRec.sampler, ERadiance);
Spectrum bsdfVal = bsdf->sample(bRec, rRec.nextSample2D());
if (bsdfVal.isZero())
if (bsdfVal.isZero())
break;
/* Recursively gather indirect illumination? */
@ -223,8 +223,12 @@ public:
if ((rRec.depth < m_maxDepth || m_maxDepth < 0) &&
(rRec.type & RadianceQueryRecord::EDirectSurfaceRadiance) &&
(bRec.sampledType & BSDF::EDelta) &&
!((bRec.sampledType & BSDF::ENull) && scattered))
!((bRec.sampledType & BSDF::ENull) && scattered)) {
recursiveType |= RadianceQueryRecord::EEmittedRadiance;
scattered = false;
} else {
scattered |= bRec.sampledType != BSDF::ENull;
}
/* Potentially stop the recursion if there is nothing more to do */
if (recursiveType == 0)
@ -236,28 +240,27 @@ public:
Float woDotGeoN = dot(its.geoFrame.n, wo);
if (woDotGeoN * Frame::cosTheta(bRec.wo) <= 0 && m_strictNormals)
break;
/* Keep track of the throughput, medium, and relative
refractive index along the path */
throughput *= bsdfVal;
eta *= bRec.eta;
if (its.isMediumTransition())
rRec.medium = its.getTargetMedium(wo);
/* In the next iteration, trace a ray in this direction */
ray = Ray(its.p, wo, ray.time);
scene->rayIntersect(ray, its);
scattered |= bRec.sampledType != BSDF::ENull;
}
if (rRec.depth++ >= m_rrDepth) {
/* Russian roulette: try to keep path weights equal to one,
while accounting for the solid angle compression at refractive
index boundaries. Stop with at least some probability to avoid
while accounting for the solid angle compression at refractive
index boundaries. Stop with at least some probability to avoid
getting stuck (e.g. due to total internal reflection) */
Float q = std::min(throughput.max() * eta * eta, (Float) 0.95f);
if (rRec.nextSample1D() >= q)
if (rRec.nextSample1D() >= q)
break;
throughput /= q;
}