Function FitOrthoSphere

engine/Poseidon/Graphics/Shadow/ShadowMath.cpp:517–546

}

OrthoFit FitOrthoSphere(const Mat4& lightView, const Vec3& center, float radius, int resolution, float zPad)
{
    OrthoFit fit;
    if (radius < 1e-4f)
    {
        radius = 1e-4f;
    }
    int res = resolution > 0 ? resolution : 1;

    Vec3 lc = TransformPoint(lightView, center);
    float diam = 2.0f * radius;
    float texel = diam / static_cast<float>(res);

    // Snap the min corner to the texel grid, then pad one texel each side so the
    // snap can never clip the sphere. Extent stays a fixed multiple of the texel,
    // so the projection scale is identical frame to frame.
    float minX = std::floor((lc.x - radius) / texel) * texel - texel;
    float minY = std::floor((lc.y - radius) / texel) * texel - texel;
    float ext = diam + 2.0f * texel;
    float maxX = minX + ext;
    float maxY = minY + ext;

    float zMin = lc.z - radius;
    float zMax = lc.z + radius + std::max(0.0f, zPad);

    fit.minB = {minX, minY, zMin};
    fit.maxB = {maxX, maxY, zMax};
    fit.proj = Ortho(minX, maxX, minY, maxY, -zMax, -zMin);
    return fit;
}

Mat4 ComputeCascadeLightVP(const Vec3& sunDir, const Vec3& up, const Mat4& invCameraViewProj, float t0, float t1,
                           int resolution, float zPad)