Method SetupForPlanarViewStable

src/render/CascadedShadowMap.cpp:152–226

}

bool CascadedShadowMap::SetupForPlanarViewStable(const DirectionalLight& light, frustum projectionFrustum, affine3 inverseViewMatrix, float maxShadowDistance, float lightSpaceZUp, float lightSpaceZDown, float exponent, float3 preViewTranslation, int numberOfCascades)
{
    assert(exponent > 1);
    
    assert(length(projectionFrustum.planes[frustum::NEAR_PLANE].normal) > 0);

    if (numberOfCascades < 0)
        m_NumberOfCascades = static_cast<int>(m_Cascades.size());
    else
        m_NumberOfCascades = std::min(numberOfCascades, static_cast<int>(m_Cascades.size()));

    if (maxShadowDistance > 0.f)
    {
        plane& nearPlane = projectionFrustum.nearPlane();
        plane& farPlane = projectionFrustum.farPlane();
        farPlane.normal = -nearPlane.normal;
        farPlane.distance = -nearPlane.distance + maxShadowDistance;
    }
    else
    {
        assert(length(projectionFrustum.planes[frustum::FAR_PLANE].normal) > 0);
    }

    std::array<float3, frustum::numCorners> corners;
    for (uint32_t i = 0; i < frustum::numCorners; i++)
    {
        corners[i] = projectionFrustum.getCorner(i);
    }

    float far = 1.f;
    float near = far / exponent;
    
    bool viewModified = false;

    for (int cascade = m_NumberOfCascades - 1; cascade >= 0; cascade--)
    {
        if (cascade == 0)
            near = 0.f;

        std::array<float3, frustum::numCorners> cascadeCorners;
        for (uint32_t i = 0; i < frustum::numCorners; i++)
        {
            cascadeCorners[i] = lerp(corners[i & 3], corners[(i & 3) + 4], (i & 4) ? far : near);
        }

        float3 nearDiagonalCenter = (cascadeCorners[frustum::C_BOTTOM | frustum::C_LEFT | frustum::C_NEAR] + cascadeCorners[frustum::C_TOP | frustum::C_RIGHT | frustum::C_NEAR]) * 0.5f;
        float3 farDiagonalCenter = (cascadeCorners[frustum::C_BOTTOM | frustum::C_LEFT | frustum::C_FAR] + cascadeCorners[frustum::C_TOP | frustum::C_RIGHT | frustum::C_FAR]) * 0.5f;
        float nearCenterToFarCenter = length(farDiagonalCenter - nearDiagonalCenter);
        float nearDiagonalHalfLength = length(cascadeCorners[frustum::C_BOTTOM | frustum::C_LEFT | frustum::C_NEAR] - cascadeCorners[frustum::C_TOP | frustum::C_RIGHT | frustum::C_NEAR]) * 0.5f;
        float farDiagonalHalfLength = length(cascadeCorners[frustum::C_BOTTOM | frustum::C_LEFT | frustum::C_FAR] - cascadeCorners[frustum::C_TOP | frustum::C_RIGHT | frustum::C_FAR]) * 0.5f;

        float nearCenterToSphereCenter = (square(nearCenterToFarCenter) + square(farDiagonalHalfLength) - square(nearDiagonalHalfLength)) / (2.f * nearCenterToFarCenter);
        nearCenterToSphereCenter = clamp(nearCenterToSphereCenter, 0.f, nearCenterToFarCenter);
        float3 sphereCenter = nearDiagonalCenter + normalize(farDiagonalCenter - nearDiagonalCenter) * nearCenterToSphereCenter;
        float sphereRadius = sqrtf(square(farDiagonalHalfLength) + square(nearCenterToFarCenter - nearCenterToSphereCenter));

        float3 cascadeCenter = inverseViewMatrix.transformPoint(sphereCenter);