Method update_cascades

libraries/lib-engine/src/renderer-pbr.cpp:24–108

}

void stable_cascaded_shadows::update_cascades(const float4x4 & view, const float near, const float far, const float aspectRatio, const float vfov, const float3 & lightDir)
{
    nearPlanes.clear();
    farPlanes.clear();
    splitPlanes.clear();
    viewMatrices.clear();
    projMatrices.clear();
    shadowMatrices.clear();

    for (size_t C = 0; C < uniforms::NUM_CASCADES; ++C)
    {
        const float splitIdx = uniforms::NUM_CASCADES;

        // Find the split planes using GPU Gem 3. Chap 10 "Practical Split Scheme".
        // http://http.developer.nvidia.com/GPUGems3/gpugems3_ch10.html
        const float splitNear = C > 0 ? mix(near + (static_cast<float>(C) / splitIdx) * (far - near),
            near * pow(far / near, static_cast<float>(C) / splitIdx), splitLambda) : near;

        const float splitFar = C < splitIdx - 1 ? mix(near + (static_cast<float>(C + 1) / splitIdx) * (far - near),
            near * pow(far / near, static_cast<float>(C + 1) / splitIdx), splitLambda) : far;

        const float4x4 splitProjectionMatrix = make_projection_matrix(vfov, aspectRatio, splitNear, splitFar);

        // Extract the frustum points
        float4 splitFrustumVerts[8] = {
            { -1.f, -1.f, -1.f, 1.f }, // Near plane
            { -1.f,  1.f, -1.f, 1.f },
            { +1.f,  1.f, -1.f, 1.f },
            { +1.f, -1.f, -1.f, 1.f },
            { -1.f, -1.f,  1.f, 1.f }, // Far plane
            { -1.f,  1.f,  1.f, 1.f },
            { +1.f,  1.f,  1.f, 1.f },
            { +1.f, -1.f,  1.f, 1.f }
        };

        for (unsigned int j = 0; j < 8; ++j)
        {
            splitFrustumVerts[j] = float4(transform_coord(inverse((splitProjectionMatrix * view)), splitFrustumVerts[j].xyz), 1);
        }

        float3 frustumCentroid = float3(0, 0, 0);
        for (size_t i = 0; i < 8; ++i) frustumCentroid += splitFrustumVerts[i].xyz;
        frustumCentroid /= 8.0f;

        // Calculate the radius of a bounding sphere surrounding the frustum corners in worldspace
        // This can be precomputed if the camera frustum does not change
        float sphereRadius = 0.0f;
        for (int i = 0; i < 8; ++i)
        {
            const float dist = length(splitFrustumVerts[i].xyz - frustumCentroid) * 1.0f;
            sphereRadius = std::max(sphereRadius, dist);
        }

        sphereRadius = (std::ceil(sphereRadius * 16.0f) / 16.0f);

        const float3 maxExtents = float3(sphereRadius, sphereRadius, sphereRadius);
        const float3 minExtents = -maxExtents;