Function FitOrtho

engine/Poseidon/Graphics/Shadow/ShadowMath.cpp:250–296

}

OrthoFit FitOrtho(const Mat4& lightView, const Vec3* pts, int count)
{
    OrthoFit fit;
    fit.proj = Identity();
    if (count <= 0 || pts == nullptr)
    {
        fit.minB = {};
        fit.maxB = {};
        return fit;
    }

    Vec3 mn = TransformPoint(lightView, pts[0]);
    Vec3 mx = mn;
    for (int i = 1; i < count; i++)
    {
        Vec3 p = TransformPoint(lightView, pts[i]);
        mn = Min(mn, p);
        mx = Max(mx, p);
    }

    // Guard degenerate (zero-extent) axes so the ortho never divides by zero.
    const float eps = 1e-4f;
    if (mx.x - mn.x < eps)
    {
        mx.x += eps;
        mn.x -= eps;
    }
    if (mx.y - mn.y < eps)
    {
        mx.y += eps;
        mn.y -= eps;
    }
    if (mx.z - mn.z < eps)
    {
        mx.z += eps;
        mn.z -= eps;
    }

    fit.minB = mn;
    fit.maxB = mx;
    // Light space looks down -Z, so points in front have negative z; the near
    // plane (closest to the light) is at the largest z = -maxB.z.
    float n = -mx.z;
    float f = -mn.z;
    fit.proj = Ortho(mn.x, mx.x, mn.y, mx.y, n, f);
    return fit;
}

OrthoFit SnapToTexelGrid(const OrthoFit& fit, int resolution)
{