static XElement MapTextureOrColor(TextureRgb texture, string name)
{
if (texture.IsConstant)
{
var clr = texture.Lookup(Vector2.Zero);
return(new XElement("rgb", MakeNameValue(name, $"{clr.R}, {clr.G}, {clr.B}")));
}
else
{
texCounter++;
string filename = $"Textures/texture-{texCounter:0000}.exr";
texture.Image.WriteToFile(filename);
return(new("texture", new XAttribute("type", "bitmap"), new XAttribute("name", name),
new XElement("string", MakeNameValue("filename", filename))
));
}
}
/// <summary>
/// Converts a parsed .obj file into one or more triangle meshes and adds it to the scene.
/// We are using our own code and not Assimp.NET, as the latter does not correctly handle meshes
/// with multiple materials assigned to different faces.
/// </summary>
/// <param name="mesh">The parsed .obj mesh</param>
/// <param name="scene">The scene to which the mesh should be added</param>
/// <param name="materialOverride">
/// Materials from the .obj with a name matching one of the keys in this dictionary will be
/// replaced by the corresponding dictionary entry
/// </param>
/// <param name="emissionOverride">
/// If a material name is a key in this dictionary, all meshes with that material will be
/// converted to diffuse emitters. The value from the dictionary determines their emitted radiance.
/// </param>
public static void AddToScene(ObjMesh mesh, Scene scene, Dictionary <string, Material> materialOverride,
Dictionary <string, RgbColor> emissionOverride = null)
{
// Create a dummy constant texture color for incorrect texture references
var dummyColor = new TextureRgb(RgbColor.White);
var dummyMaterial = new GenericMaterial(new GenericMaterial.Parameters {
BaseColor = dummyColor
});
// Create the materials for this OBJ file
var errors = new List <string>();
var materials = new Dictionary <string, Material>();
var emitters = new Dictionary <string, RgbColor>();
for (int i = 1, n = mesh.Contents.Materials.Count; i < n; i++)
{
// Try to find the correct material
string materialName = mesh.Contents.Materials[i];
ObjMesh.Material objMaterial;
if (!mesh.Contents.MaterialLib.TryGetValue(materialName, out objMaterial))
{
errors.Add($"Cannot find material '{materialName}'. Replacing by dummy.");
materials[materialName] = dummyMaterial;
continue;
}
// Roughly match the different illumination modes to the right parameters of our material.
GenericMaterial.Parameters materialParameters;
switch (objMaterial.illuminationModel)
{
case 5: // perfect mirror
materialParameters = new GenericMaterial.Parameters {
BaseColor = new TextureRgb(objMaterial.specular),
SpecularTintStrength = 1.0f,
Metallic = 1,
Roughness = new TextureMono(0),
};
break;
case 7: // perfect glass
materialParameters = new GenericMaterial.Parameters {
BaseColor = new TextureRgb(objMaterial.specular),
Metallic = 0,
Roughness = new TextureMono(0),
IndexOfRefraction = objMaterial.indexOfRefraction,
SpecularTransmittance = 1.0f,
SpecularTintStrength = 1.0f
};
break;
case 2:
default: // We pretend that anything else would be "2", aka, a phong shader
TextureRgb baseColor;
baseColor = string.IsNullOrEmpty(objMaterial.diffuseTexture)
? new TextureRgb(objMaterial.diffuse)
: new TextureRgb(System.IO.Path.Join(mesh.BasePath, objMaterial.diffuseTexture));
// We coarsely map the "ns" term to roughness, use the diffuse color as base color,
// and ignore everything else.
materialParameters = new GenericMaterial.Parameters {
BaseColor = baseColor,
Roughness = new TextureMono(
objMaterial.specularIndex == 0
? 1
: 1 / objMaterial.specularIndex),
Metallic = 0.5f
};
break;
}
materials[materialName] = new GenericMaterial(materialParameters);
// Check if the material is emissive
if (objMaterial.emission != RgbColor.Black)
{
emitters[materialName] = objMaterial.emission;
}
}
// Convert the faces to triangles & build the new list of indices
foreach (var obj in mesh.Contents.Objects)
{
// Mapping from material index to triangle definition, per group
var triangleGroups = new List <Dictionary <int, List <TriIdx> > >();
// Triangulate faces and group triangles by material
bool has_normals = false;
bool has_texcoords = false;
bool empty = true;
foreach (var group in obj.Groups)
{
// Create the mapping from material index to triangle definition for this group.
triangleGroups.Add(new Dictionary <int, List <TriIdx> >());
foreach (var face in group.Faces)
{
int mtl_idx = face.Material;
triangleGroups[^ 1].TryAdd(mtl_idx, new List <TriIdx>());
