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// Copyright 2009 Intel Corporation
// SPDX-License-Identifier: Apache-2.0
#include "render/pathtracer/NextEventEstimation.ih"
#include "render/pathtracer/PathStructs.ih"
#include "render/pathtracer/PathTracerDefines.ih"
#include "render/pathtracer/PathTracerUtil.ih"
#include "render/pathtracer/TransparentShadow.ih"
#ifdef OSPRAY_ENABLE_VOLUMES
#include "render/pathtracer/volumes/VolumeSampler.ih"
#endif
#include "common/RayCone.ih"
#include "common/World.ih"
#include "math/Distribution1D.ih"
#include "math/random.ih"
#include "math/sampling.ih"
// c++ shared
#include "lights/LightDispatch.ih"
#include "lights/LightShared.h"
OSPRAY_BEGIN_ISPC_NAMESPACE
SYCL_EXTERNAL vec3f nextEventEstimation(const PathContext &pathContext,
PathState &pathState,
PathVertex &pathVertex,
float rayConeWidth,
const uniform FeatureFlagsHandler &ffh)
{
const uniform FeatureFlags ff = getFeatureFlags(ffh);
// direct lighting including shadows and MIS
vec3f L = make_vec3f(0.f);
const uint32 numLightSamples = pathState.firstBounceLight
? pathContext.numFirstBounceLightSamples
: pathContext.numIndirectBounceLightSamples;
// remember for MIS
pathVertex.numLightSamples = numLightSamples;
for (uniform uint32 i = 0; i < numLightSamples; i++) {
// select a random light source from the list
float ss;
const vec2f s = LDSampler_get3LightSamples(
pathState.ldSampler, i, numLightSamples > 1, ss);
const Sample1D lSelectSample = Distribution1D_sample(
pathContext.numLights, pathContext.lightsCDF, 0, ss);
const float lightSelectionProb = lSelectSample.prob * numLightSamples;
const Light *light = pathContext.lights[lSelectSample.idx];
// sample the contribution from the random light source
Light_SampleRes ls;
foreach_unique (l in light)
ls = Light_dispatch_sample(l, pathVertex.dg, s, pathState.time, ffh);
// adjust the contribution with the probabiltiy of selecting the light
// source
ls.weight = ls.weight / lightSelectionProb;
ls.pdf *= lightSelectionProb;
// skip when zero contribution from light
if (reduce_max(ls.weight) <= 0.0f | ls.pdf <= PDF_CULLING)
continue;
// evaluate BSDF
Scattering_EvalRes fe;
if (ff.geometry && pathVertex.type == SURFACE) {
foreach_unique (f in pathVertex.bsdf)
if (f != NULL)
fe = BSDF_dispatch_eval(f, pathVertex.wo, ls.dir, ffh);
} else {
#ifdef OSPRAY_ENABLE_VOLUMES
if (ff.other & FFO_VOLUME_IN_SCENE) {
foreach_unique (v in pathVertex.volume)
if (v != NULL)
fe = HenyeyGreenstein_eval(v->anisotropy, pathVertex.wo, ls.dir);
}
#endif
}
// skip when zero contribution from material
if (reduce_max(fe.value) <= 0.0f)
continue;
// test for shadows with rayCones
Ray shadowRay;
vec3f org = pathVertex.dg.P;
if (pathVertex.type != VOLUME) {
if (dot(pathVertex.dg.Ng, ls.dir) < 0.f)
org = org - (2.0f * pathVertex.dg.epsilon) * pathVertex.dg.Ng;
}
setRay(shadowRay, org, ls.dir, 0.f, ls.dist, pathState.time);
// connect ray cone to point on light
RayCone shadowCone;
shadowCone.width = rayConeWidth;
shadowCone.dwdt = -rayConeWidth * rcp(ls.dist);
// Trace ray in clipping geometries scene, fill array with ray intervals
RayIntervals rayIntervals;
traceClippingRay(pathContext.world, shadowRay, rayIntervals, ffh);
const vec3f throughput = pathState.throughput * fe.value;
const vec3f unshadedLightContrib = throughput * ls.weight;
const vec3f lightContrib = transparentShadow(pathContext.context,
pathContext.world,
unshadedLightContrib,
shadowRay,
shadowCone,
rayIntervals,
pathState.currentMedium,
ffh);
if (reduce_max(lightContrib) > 0) {
#ifdef OSPRAY_ENABLE_VOLUMES
if (ff.other & FFO_VOLUME_IN_SCENE) {
const float T = volumeTransmittance(pathContext.world,
shadowRay,
rayIntervals,
&pathState.randomSampler,
ffh);
if (reduce_max(T) > 0) {
// we have to use an independent transmittance estimate for MIS to get
// a correct result
const float T_mis =
#ifdef OSPRAY_PATHTRACER_DEBUG
pathContext.disableFWD || pathContext.disableNEE
? 1.f
:
#endif
volumeTransmittance(pathContext.world,
shadowRay,
rayIntervals,
&pathState.randomSampler,
ffh);
L = L
+ T * lightContrib
* misHeuristic(pathContext, ls.pdf, fe.pdf * T_mis);
}
} else
#endif
{
L = L + lightContrib * misHeuristic(pathContext, ls.pdf, fe.pdf);
}
}
}
return L;
}
OSPRAY_END_ISPC_NAMESPACE
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