C++ VisibilityTester::P1方法代码示例

Spectrum ConnectBDPT(const Scene &scene, Vertex *lightVertices,
                     Vertex *cameraVertices, int s, int t,
                     const Distribution1D &lightDistr, const Camera &camera,
                     Sampler &sampler, Point2f *pRaster, Float *misWeightPtr) {
    Spectrum L(0.f);
    // Ignore invalid connections related to infinite area lights
    if (t > 1 && s != 0 && cameraVertices[t - 1].type == VertexType::Light)
        return Spectrum(0.f);

    // Perform connection and write contribution to _L_
    Vertex sampled;
    if (s == 0) {
        // Interpret the camera subpath as a complete path
        const Vertex &pt = cameraVertices[t - 1];
        if (pt.IsLight()) L = pt.Le(scene, cameraVertices[t - 2]) * pt.beta;
    } else if (t == 1) {
        // Sample a point on the camera and connect it to the light subpath
        const Vertex &qs = lightVertices[s - 1];
        if (qs.IsConnectible()) {
            VisibilityTester vis;
            Vector3f wi;
            Float pdf;
            Spectrum Wi = camera.Sample_Wi(qs.GetInteraction(), sampler.Get2D(),
                                           &wi, &pdf, pRaster, &vis);
            if (pdf > 0 && !Wi.IsBlack()) {
                // Initialize dynamically sampled vertex and _L_ for $t=1$ case
                sampled = Vertex::CreateCamera(&camera, vis.P1(), Wi / pdf);
                L = qs.beta * qs.f(sampled) * vis.Tr(scene, sampler) *
                    sampled.beta;
                if (qs.IsOnSurface()) L *= AbsDot(wi, qs.ns());
            }
        }
    } else if (s == 1) {
        // Sample a point on a light and connect it to the camera subpath
        const Vertex &pt = cameraVertices[t - 1];
        if (pt.IsConnectible()) {
            Float lightPdf;
            VisibilityTester vis;
            Vector3f wi;
            Float pdf;
            int lightNum =
                lightDistr.SampleDiscrete(sampler.Get1D(), &lightPdf);
            const std::shared_ptr<Light> &light = scene.lights[lightNum];
            Spectrum lightWeight = light->Sample_Li(
                pt.GetInteraction(), sampler.Get2D(), &wi, &pdf, &vis);
            if (pdf > 0 && !lightWeight.IsBlack()) {
                EndpointInteraction ei(vis.P1(), light.get());
                sampled =
                    Vertex::CreateLight(ei, lightWeight / (pdf * lightPdf), 0);
                sampled.pdfFwd = sampled.PdfLightOrigin(scene, pt, lightDistr);
                L = pt.beta * pt.f(sampled) * vis.Tr(scene, sampler) *
                    sampled.beta;
                if (pt.IsOnSurface()) L *= AbsDot(wi, pt.ns());
            }
        }
    } else {
        // Handle all other bidirectional connection cases
        const Vertex &qs = lightVertices[s - 1], &pt = cameraVertices[t - 1];
        if (qs.IsConnectible() && pt.IsConnectible()) {
            L = qs.beta * qs.f(pt) * pt.f(qs) * pt.beta;
            if (!L.IsBlack()) L *= G(scene, sampler, qs, pt);
        }
    }

    // Compute MIS weight for connection strategy
    Float misWeight =
        L.IsBlack() ? 0.f : MISWeight(scene, lightVertices, cameraVertices,
                                      sampled, s, t, lightDistr);
    L *= misWeight;
    if (misWeightPtr) *misWeightPtr = misWeight;
    return L;
}

Spectrum ConnectBDPT(
    const Scene &scene, Vertex *lightVertices, Vertex *cameraVertices, int s,
    int t, const Distribution1D &lightDistr,
    const std::unordered_map<const Light *, size_t> &lightToIndex,
    const Camera &camera, Sampler &sampler, Point2f *pRaster,
    Float *misWeightPtr) {
    Spectrum L(0.f);
    // Ignore invalid connections related to infinite area lights
    if (t > 1 && s != 0 && cameraVertices[t - 1].type == VertexType::Light)
        return Spectrum(0.f);

    // Perform connection and write contribution to _L_
    Vertex sampled;
    if (s == 0) {
        // Interpret the camera subpath as a complete path
        const Vertex &pt = cameraVertices[t - 1];
        if (pt.IsLight()) L = pt.Le(scene, cameraVertices[t - 2]) * pt.beta;
        DCHECK(!L.HasNaNs());
    } else if (t == 1) {
        // Sample a point on the camera and connect it to the light subpath
        const Vertex &qs = lightVertices[s - 1];
        if (qs.IsConnectible()) {
            VisibilityTester vis;
            Vector3f wi;
            Float pdf;
            Spectrum Wi = camera.Sample_Wi(qs.GetInteraction(), sampler.Get2D(),
                                           &wi, &pdf, pRaster, &vis);
            if (pdf > 0 && !Wi.IsBlack()) {
                // Initialize dynamically sampled vertex and _L_ for $t=1$ case
                sampled = Vertex::CreateCamera(&camera, vis.P1(), Wi / pdf);
                L = qs.beta * qs.f(sampled, TransportMode::Importance) * sampled.beta;
                if (qs.IsOnSurface()) L *= AbsDot(wi, qs.ns());
                DCHECK(!L.HasNaNs());
                // Only check visibility after we know that the path would
                // make a non-zero contribution.
                if (!L.IsBlack()) L *= vis.Tr(scene, sampler);
            }
        }
    } else if (s == 1) {
        // Sample a point on a light and connect it to the camera subpath
        const Vertex &pt = cameraVertices[t - 1];
        if (pt.IsConnectible()) {
            Float lightPdf;
            VisibilityTester vis;
            Vector3f wi;
            Float pdf;
            int lightNum =
                lightDistr.SampleDiscrete(sampler.Get1D(), &lightPdf);
            const std::shared_ptr<Light> &light = scene.lights[lightNum];
            Spectrum lightWeight = light->Sample_Li(
                pt.GetInteraction(), sampler.Get2D(), &wi, &pdf, &vis);
            if (pdf > 0 && !lightWeight.IsBlack()) {
                EndpointInteraction ei(vis.P1(), light.get());
                sampled =
                    Vertex::CreateLight(ei, lightWeight / (pdf * lightPdf), 0);
                sampled.pdfFwd =
                    sampled.PdfLightOrigin(scene, pt, lightDistr, lightToIndex);
                L = pt.beta * pt.f(sampled, TransportMode::Radiance) * sampled.beta;
                if (pt.IsOnSurface()) L *= AbsDot(wi, pt.ns());
                // Only check visibility if the path would carry radiance.
                if (!L.IsBlack()) L *= vis.Tr(scene, sampler);
            }
        }
    } else {
        // Handle all other bidirectional connection cases
        const Vertex &qs = lightVertices[s - 1], &pt = cameraVertices[t - 1];
        if (qs.IsConnectible() && pt.IsConnectible()) {
            L = qs.beta * qs.f(pt, TransportMode::Importance) * pt.f(qs, TransportMode::Radiance) * pt.beta;
            VLOG(2) << "General connect s: " << s << ", t: " << t <<
                " qs: " << qs << ", pt: " << pt << ", qs.f(pt): " << qs.f(pt, TransportMode::Importance) <<
                ", pt.f(qs): " << pt.f(qs, TransportMode::Radiance) << ", G: " << G(scene, sampler, qs, pt) <<
                ", dist^2: " << DistanceSquared(qs.p(), pt.p());
            if (!L.IsBlack()) L *= G(scene, sampler, qs, pt);
        }
    }

    ++totalPaths;
    if (L.IsBlack()) ++zeroRadiancePaths;
    ReportValue(pathLength, s + t - 2);

    // Compute MIS weight for connection strategy
    Float misWeight =
        L.IsBlack() ? 0.f : MISWeight(scene, lightVertices, cameraVertices,
                                      sampled, s, t, lightDistr, lightToIndex);
    VLOG(2) << "MIS weight for (s,t) = (" << s << ", " << t << ") connection: "
            << misWeight;
    DCHECK(!std::isnan(misWeight));
    L *= misWeight;
    if (misWeightPtr) *misWeightPtr = misWeight;
    return L;
}

Spectrum ConnectBDPT(const Scene &scene, Vertex *lightSubpath,
                     Vertex *cameraSubpath, int s, int t,
                     const Distribution1D &lightDistr, const Camera &camera,
                     Sampler &sampler, Point2f *rasterPos, Float *misWeight) {
    Spectrum weight(0.f);
    // Ignore invalid connections related to infinite area lights
    if (t > 1 && s != 0 && cameraSubpath[t - 1].type == VertexType::Light)
        return Spectrum(0.f);

    // Perform connection and write contribution to _weight_
    Vertex sampled;
    if (s == 0) {
        // Interpret the camera subpath as a complete path
        const Vertex &pt = cameraSubpath[t - 1];
        if (pt.IsLight()) {
            const Vertex &ptMinus = cameraSubpath[t - 2];
            weight = pt.Le(scene, ptMinus) * pt.weight;
        }
    } else if (t == 1) {
        // Sample a point on the camera and connect it to the light subpath
        const Vertex &qs = lightSubpath[s - 1];
        if (qs.IsConnectible()) {
            VisibilityTester vis;
            Vector3f wi;
            Float pdf;
            Spectrum cameraWeight =
                camera.Sample_We(qs.GetInteraction(), sampler.Get2D(), &wi,
                                 &pdf, rasterPos, &vis);
            if (pdf > 0 && !cameraWeight.IsBlack()) {
                // Initialize dynamically sampled vertex and _weight_
                sampled = Vertex(VertexType::Camera,
                                 EndpointInteraction(vis.P1(), &camera),
                                 cameraWeight);
                weight = qs.weight * qs.f(sampled) * vis.T(scene, sampler) *
                         sampled.weight;
                if (qs.IsOnSurface())
                    weight *= AbsDot(wi, qs.GetShadingNormal());
            }
        }
    } else if (s == 1) {
        // Sample a point on a light and connect it to the camera subpath
        const Vertex &pt = cameraSubpath[t - 1];
        if (pt.IsConnectible()) {
            Float lightPdf;
            VisibilityTester vis;
            Vector3f wi;
            Float pdf;
            int lightNum =
                lightDistr.SampleDiscrete(sampler.Get1D(), &lightPdf);
            const std::shared_ptr<Light> &light = scene.lights[lightNum];
            Spectrum lightWeight = light->Sample_L(
                pt.GetInteraction(), sampler.Get2D(), &wi, &pdf, &vis);
            if (pdf > 0 && !lightWeight.IsBlack()) {
                sampled = Vertex(VertexType::Light,
                                 EndpointInteraction(vis.P1(), light.get()),
                                 lightWeight / (pdf * lightPdf));
                sampled.pdfFwd = sampled.PdfLightOrigin(scene, pt, lightDistr);
                weight = pt.weight * pt.f(sampled) * vis.T(scene, sampler) *
                         sampled.weight;
                if (pt.IsOnSurface())
                    weight *= AbsDot(wi, pt.GetShadingNormal());
            }
        }
    } else {
        // Handle all other cases
        const Vertex &qs = lightSubpath[s - 1], &pt = cameraSubpath[t - 1];
        if (qs.IsConnectible() && pt.IsConnectible()) {
            weight = qs.weight * qs.f(pt) *
                     GeometryTerm(scene, sampler, qs, pt) * pt.f(qs) *
                     pt.weight;
        }
    }

    // Compute MIS weight for connection strategy
    *misWeight =
        weight.IsBlack() ? 0.f : MISWeight(scene, lightSubpath, cameraSubpath,
                                           sampled, s, t, lightDistr);
    return weight;
}