/// <summary>
/// Computes the ratio of self-masked area to visible area. Used by <see cref="MaskingShadowing(Vector3)"/>.
/// </summary>
/// <param name="normal">Normal of the microfacets, in shading space.</param>
/// <returns>Ratio of self-masked area to visible area.</returns>
public float MaskingRatio(Vector3 normal)
{
float absTanTheta = MathF.Abs(ShadingSpace.TanTheta(normal));
if (float.IsInfinity(absTanTheta))
{
return(0);
}
float alpha = MathF.Sqrt(ShadingSpace.CosPhiSqr(normal) * AlphaX * AlphaX + ShadingSpace.SinPhiSqr(normal) * AlphaY * AlphaY);
float alpha2Tan2Theta = alpha * absTanTheta * (alpha * absTanTheta);
return((-1 + MathF.Sqrt(1 + alpha2Tan2Theta)) / 2);
}
