void finite_diff_grad(const M& model,
stan::callbacks::interrupt& interrupt,
std::vector<double>& params_r,
std::vector<int>& params_i,
std::vector<double>& grad,
double epsilon = 1e-6,
std::ostream* msgs = 0) {
std::vector<double> perturbed(params_r);
grad.resize(params_r.size());
for (size_t k = 0; k < params_r.size(); k++) {
interrupt();
perturbed[k] += epsilon;
double logp_plus
= model
.template log_prob<propto,
jacobian_adjust_transform>(perturbed, params_i,
msgs);
perturbed[k] = params_r[k] - epsilon;
double logp_minus
= model
.template log_prob<propto,
jacobian_adjust_transform>(perturbed, params_i,
msgs);
double gradest = (logp_plus - logp_minus) / (2*epsilon);
grad[k] = gradest;
perturbed[k] = params_r[k];
}
}
Spectrum sample(BSDFSamplingRecord &bRec, Float &pdf, const Point2 &sample) const {
const Intersection& its = bRec.its;
Intersection perturbed(its);
perturbed.shFrame = getFrame(its);
BSDFSamplingRecord perturbedQuery(perturbed, bRec.sampler, bRec.mode);
perturbedQuery.wi = perturbed.toLocal(its.toWorld(bRec.wi));
perturbedQuery.typeMask = bRec.typeMask;
perturbedQuery.component = bRec.component;
Float temporaryPdf = (Float)0;
Spectrum result = m_nested->sample(perturbedQuery, temporaryPdf, sample);
if (temporaryPdf > 0) {
bRec.sampledComponent = perturbedQuery.sampledComponent;
bRec.sampledType = perturbedQuery.sampledType;
bRec.wo = its.toLocal(perturbed.toWorld(perturbedQuery.wo));
bRec.eta = perturbedQuery.eta;
if (Frame::cosTheta(bRec.wo) * Frame::cosTheta(perturbedQuery.wo) <= 0)
return Spectrum(0.0f);
pdf = temporaryPdf;
}
return result;
}
Spectrum eval(const BSDFSamplingRecord &bRec, EMeasure measure) const {
const Intersection& its = bRec.its;
Intersection perturbed(its);
perturbed.shFrame = getFrame(its);
BSDFSamplingRecord perturbedQuery(perturbed,
perturbed.toLocal(its.toWorld(bRec.wi)),
perturbed.toLocal(its.toWorld(bRec.wo)), bRec.mode);
if (Frame::cosTheta(bRec.wo) * Frame::cosTheta(perturbedQuery.wo) <= 0)
return Spectrum(0.0f);
perturbedQuery.sampler = bRec.sampler;
perturbedQuery.typeMask = bRec.typeMask;
perturbedQuery.component = bRec.component;
return m_nested->eval(perturbedQuery, measure);
}
template<Pb PS> bool circles_overlap(const ExactCircle<PS>& c0, const ExactCircle<PS>& c1) {
return perturbed_predicate<Intersect<true >>(perturbed(c0),perturbed(c1));
}
template<Pb PS> bool has_intersections(const ExactCircle<PS>& c0, const ExactCircle<PS>& c1) {
return perturbed_predicate<Intersect<true >>(perturbed(c0),perturbed(c1))
&& !perturbed_predicate<Intersect<false>>(perturbed(c0),perturbed(c1));
}
template<Pb PS> uint8_t circle_circle_intersection_quadrant(const ReferenceSide side, const ExactCircle<PS>& cl, const ExactCircle<PS>& cr, const ApproxIntersection v) {
assert(circle_circle_approx_intersection(cl,cr).box().intersects(v.box()));
// We must evaluate the predicate
//
// cross(e,alpha*dc+beta*dc^perp) > 0
// alpha cross(e,dc) + beta dot(e,dc) > 0
//
// where e0 = (1,0) and e1 = (0,1). This has the form
//
// A + B sqrt(C) > 0
// A = alpha_hat cross(e,dc)
// B = dot(e,dc)
// C = beta_hat^2
//
// Compute predicates for both axes
//
const ExactCircle<PS>& c0 = cl_is_reference(side) ? cl : cr;
const ExactCircle<PS>& c1 = cl_is_reference(side) ? cr : cl;
const int s = cl_is_reference(side) ? -1 : 1;
const bool p0 = FILTER(v.p().y-c0.center.y, perturbed_predicate_sqrt<QuadrantA<0>,QuadrantB<0>,Beta<0,1>>(s,perturbed(c0),perturbed(c1))),
p1 = FILTER(c0.center.x-v.p().x, perturbed_predicate_sqrt<QuadrantA<1>,QuadrantB<1>,Beta<0,1>>(s,perturbed(c0),perturbed(c1)));
// Assemble our two predicates into a quadrant
return 2*!p0+(p0==p1);
}
