/// <summary>
///
/// </summary>
/// <param name="mat"></param>
/// <returns>roughnessFactor</returns>
private static double ConvertTraditional2MetallicRoughness(WaveFront.Material mat)
{
// Transform from 0-1000 range to 0-1 range. Then invert.
//var roughnessFactor = mat.SpecularExponent; // options.metallicRoughness ? 1.0 : 0.0;
//roughnessFactor = roughnessFactor / 1000.0;
var roughnessFactor = 1.0 - mat.SpecularExponent / 1000.0;
roughnessFactor = Clamp(roughnessFactor, 0.0, 1.0);
if (mat.Specular == null || mat.Specular.Color == null)
{
mat.Specular = new Reflectivity(new Color());
return(roughnessFactor);
}
// Translate the blinn-phong model to the pbr metallic-roughness model
// Roughness factor is a combination of specular intensity and shininess
// Metallic factor is 0.0
// Textures are not converted for now
var specularIntensity = Luminance(mat.Specular.Color);
// Low specular intensity values should produce a rough material even if shininess is high.
if (specularIntensity < 0.1)
{
roughnessFactor *= (1.0 - specularIntensity);
}
var metallicFactor = 0.0;
mat.Specular = new Reflectivity(new Color(metallicFactor));
return(roughnessFactor);
}
private int AddMaterial(WaveFront.Material mat)
{
Gltf.Material gMat = null;
if (mat == null)
{
gMat = GetDefault();
}
else
{
var roughnessFactor = ConvertTraditional2MetallicRoughness(mat);
gMat = new Gltf.Material
{
Name = mat.Name,
AlphaMode = AlphaMode.OPAQUE
};
var hasTexture = !String.IsNullOrEmpty(mat.DiffuseTextureFile);
var alpha = mat.GetAlpha();
var metallicFactor = 0.0;
if (mat.Specular != null && mat.Specular.Color != null)
{
metallicFactor = mat.Specular.Color.Red;
}
gMat.PbrMetallicRoughness = new PbrMetallicRoughness
{
RoughnessFactor = roughnessFactor,
MetallicFactor = metallicFactor
};
if (mat.Diffuse != null)
{
gMat.PbrMetallicRoughness.BaseColorFactor = mat.Diffuse.Color.ToArray(alpha);
}
else if (mat.Ambient != null)
{
gMat.PbrMetallicRoughness.BaseColorFactor = mat.Ambient.Color.ToArray(alpha);
}
else
{
gMat.PbrMetallicRoughness.BaseColorFactor = new double[] { 0.7, 0.7, 0.7, alpha };
}
if (hasTexture)
{
int index = -1;
for (var i = 0; i < _model.Textures.Count; i++)
{
if (mat.DiffuseTextureFile == _model.Textures[i].Name)
{
index = i;
break;
}
}
if (index == -1)
{
index = AddTexture(mat.DiffuseTextureFile);
}
gMat.PbrMetallicRoughness.BaseColorTexture = new Info
{
Index = index
};
}
if (mat.Emissive != null && mat.Emissive.Color != null)
{
gMat.EmissiveFactor = mat.Emissive.Color.ToArray();
}
if (alpha < 1.0)
{
gMat.AlphaMode = AlphaMode.BLEND;
gMat.DoubleSided = true;
}
}
var matIndex = _model.Materials.Count;
_model.Materials.Add(gMat);
return(matIndex);
}