std::vector<double> randomshift_on_sphere(const std::vector<double> &insamples, int num_pts){
std::vector<double> output(3*num_pts, 0.0);
//Find two random vectors on the sphere
double rx=0,ry=0,rz=0;
uniformSampleSphere(drand48(), drand48(), &rx, &ry, &rz);
double temp1[] = {rx, ry, rz};
uniformSampleSphere(drand48(), drand48(), &rx, &ry, &rz);
double temp2[] = {rx, ry, rz};
//Compute a quaternion from these vectors
double quat[] = {0,0,0,1};
QuaternionFromTwoVectors(temp1, temp2, quat);
//Use the above quaternion to rotate all samples.
for(int b = 0; b < num_pts; b++){
double qmat[16], qvout[4];
double qvec[] = {insamples[3*b+0], insamples[3*b+1], insamples[3*b+2],1};
ConvertQuaternionToMatrix(quat, qmat);
MultiplyVecMat(qmat, qvec, qvout);
//rotated samples are here
output[3*b+0] = (qvout[0]);
output[3*b+1] = (qvout[1]);
output[3*b+2] = (qvout[2]);
}
return output;
}
void BackendScene::generateVPL( size_t vplNum, const char* vplFile,size_t vpldepth )
{
this->vpls.clear();
SET_CLAMPING_DISTANCE( 0.05 * sceneradius );
//------------------------- READ FILE IF IT DOES EXIST--------------------------------------
if( strcmp(vplFile,"")){
FILE *ptr;
ptr = fopen(vplFile,"rb");
if (ptr)
{
size_t siz;
fread(&siz,sizeof(size_t),1,ptr);
vpls.resize(siz);
for (size_t i = 0 ; i<siz; ++i)
vpls[i].read(ptr);
fclose(ptr);
std::cout << "Vpl file read. Total # of vpls:"<< vpls.size()<<std::endl;
return;
}
else std::cout << "Unable to read vpl file."<< std::endl;
}
//------------------------- OTHERWISE GENERATE VPLS--------------------------------------
Random rnd(RND_SEED);
// Place VPLs that substitute the original lights (direct VPLs)
std::vector<Ref<Light> >::iterator it = allLights.begin();
for ( ; it !=allLights.end(); ++it)
{
// Replace TriangleLight
if( (*it).dynamicCast<TriangleLight>() )
{
Ref<TriangleLight> tr = (*it).dynamicCast<TriangleLight>();
Color I = tr->L * length(cross(tr->e1,tr->e2)) * 0.5;
int triangleSamples = 1024;
// HACK to avoid too many VPLs for many quads...
if (allLights.size() > 2000)
triangleSamples = 100;
for (int i=0 ; i < triangleSamples ; ++i)
{
Vector3f pos = uniformSampleTriangle(rnd.getFloat(),rnd.getFloat(),tr->v0,tr->v1,tr->v2);
this->vpls.push_back(vplVPL(pos, -tr->Ng, I * rcp((float)triangleSamples) ) );
}
}
// Replace SpotLight
else if ((*it).dynamicCast<SpotLight>())
{
Ref<SpotLight> sl = (*it).dynamicCast<SpotLight>();
if ( sl->cosAngleMax >= 0.05 || sl->cosAngleMin <= 0.95 )
throw std::runtime_error("Not supporting spotlights with other than 90 degree falloff for VPL generation.");
this->vpls.push_back(vplVPL(sl->P,sl->_D,sl->I));
}
// Replace environment map
else if ((*it).dynamicCast<HDRILight>())
{
Ref<HDRILight> hd = (*it).dynamicCast<HDRILight>();
int envmapSamples = 32768;
float dirlightdistance = DIR_LIGHT_DISTANCE;
for (int i=0 ; i < envmapSamples ; ++i)
{
Vector3f pos(uniformSampleSphere(rnd.getFloat(),rnd.getFloat()));
Vector3f dir = -pos;
pos *= dirlightdistance; pos += scenecenter;
// CHECK below line later it is not completely precise
Color I = hd->Le(-dir) * four_pi * rcp((float)envmapSamples) * dirlightdistance * dirlightdistance;
this->vpls.push_back(vplVPL(pos, -dir , I ));
}
}
else if ((*it).dynamicCast<DirectionalLight>())
{
Ref<DirectionalLight> sl = (*it).dynamicCast<DirectionalLight>();
float distance = 100000;
this->vpls.push_back(vplVPL(sl->_wo*distance,sl->_wo,sl->E*distance*distance));
}
else
throw std::runtime_error("Not supported light type for VPL generation.");
}
// Place VPLs (indirect VPLs)
size_t direct = this->vpls.size();
size_t orig = this->allLights.size();
if (vpldepth <=1) return;
while (this->vpls.size() < (vplNum+direct))
{
// Sample orig lights for photons
Ref<Light> vp = this->allLights[rnd.getInt(orig)];
Vector3f pos;
Sample3f dir;
Vec2f vr(rnd.getFloat(),rnd.getFloat());
Vec2f vs(rnd.getFloat(),rnd.getFloat());
Color I = vp->samplePhoton(dir,pos,vr,vs,sceneradius,scenecenter);
if (dir.pdf==0.0f) continue;
I *= (float) orig * rcp(dir.pdf);
// Generate a path for the photon and add VPLs
int maxdepth = int(vpldepth) - 1; // -1 because 1 for pt means only direct light
while ( maxdepth-- && (I != zero ) )
{
Ray ray (pos,dir,32*std::numeric_limits<float>::epsilon(), inf);
DifferentialGeometry dg;
rtcIntersect(this->scene,(RTCRay&)ray);
this->postIntersect(ray,dg);
if (!ray)//nothing is hit
break;
/*! face forward normals */
if (dot(dg.Ng, ray.dir) > 0)
{
dg.Ng = -dg.Ng; dg.Ns = -dg.Ns;
}
CompositedBRDF brdfs;
if (dg.material) dg.material->shade(ray, Medium::Vacuum(), dg, brdfs);
BRDFType diffuseBRDFTypes = (BRDFType)(DIFFUSE);
Vec2f s = Vec2f(rnd.getFloat(),rnd.getFloat());
Color c = brdfs.sample(-ray.dir,dg, dir,diffuseBRDFTypes,s,rnd.getFloat(),diffuseBRDFTypes);
if (c==zero || dir.pdf==0.0f) break;
// the dot prod should not be zero since then c would be zero
float dott = dot(dir,dg.Ns);
if (dott==0.0f) break;
Color contrib = I * c * rcp(dott) * rcp((float)vplNum) ;
//if (std::isnan(contrib.r) || std::isnan(contrib.g) || std::isnan(contrib.b))
// break;
this->vpls.push_back(vplVPL(dg.P,-dg.Ns,contrib));
Color contribScale = c * rcp(dir.pdf);
float rrProb = min(1.0f, reduce_avg(contribScale));
if(rrProb == 0.0f)break;
if (rnd.getFloat() > rrProb)
break;
I *= contribScale * rcp(rrProb);
pos = dg.P;
}
}
//------------------------------PERTURB VPLS WITH THE SAME POSITION-----------------------------------------------------------
auto vplComp = [] (const vplVPL& vp1,const vplVPL& vp2) { return vp1.P < vp2.P; };
std::sort(this->vpls.begin(),this->vpls.end(),vplComp);
std::vector<vplVPL>::iterator itt = this->vpls.begin();
while(itt != ( vpls.end() - 1 ) && itt != vpls.end())
{
vplVPL& v1 = *itt, & v2 = *(itt+1);
if(v1.P == v2.P)
{
v2.I += v1.I;
itt = this->vpls.erase(itt);
}
else
++itt;
}
//------------------------------WRITE OUT VPLS INTO A FILE-----------------------------------------------------------
// writing out the VPLs
FILE *ptr;
ptr = fopen(vplFile,"wb");
if (ptr)
{
size_t siz = this->vpls.size();
fwrite(&siz,sizeof(size_t),1,ptr);
if (vpls.size())
for (size_t i = 0 ; i<siz; ++i)
vpls[i].write(ptr);
fclose(ptr);
std::cout << "Vpl file written. Total # of vpls:"<< vpls.size()<<std::endl;
}
else std::cout << "Unable to write vpl file. Total # of vpls: "<<vpls.size() << std::endl;
return;
}