static SmoothnessMapChannel GetSmoothnessMapChannel(Material material)
{
int ch = (int) material.GetFloat("_SmoothnessTextureChannel");
if (ch == (int) SmoothnessMapChannel.AlbedoAlpha)
return SmoothnessMapChannel.AlbedoAlpha;
else
return SmoothnessMapChannel.SpecularMetallicAlpha;
}