Wavefront obj (.mtl) with PBR ?

AFsoft

Hi everyone.

I have a personal project that i must export obj format with .mtl file.

The models must be in PBR standard Metal/Roughness. is it possible ?

i found out some articles on the internet that i could address diffuse/base color and Bump maps. but i dont know if it supports

Metalic and roughness or not. any help is much appreciated !

example .mtl code :

map_Kd shoe09_attachment_part_BaseColor.png

map_Bump shoe09_attachment_part_Normal.png

Eric Chadwick

Exporting from which software, and importing into what? There's probably a better format for this, like glTF (nice support in Blender).

I think I have a resource on the mtl format, I'll see if I can find it. It depends on the exporter, but I suppose you could tweak the file post-export.

Eric Chadwick

http://www.paulbourke.net/dataformats/mtl/

I guess you could shoehorn metal-rough textures into the existing slots, and make your own importer to read those.

Klunk

the "standard" obj format is quite limiting, eg no support for vertex colour though if you have "control" on both export and import side of the equation then it's relatively easy to extend it to cover any possibility otherwise you're limited to your default apps importer.

I think what i'm trying to say badly (beer brain as it's nye) you'll need to write both an exporter and an importer .

myclay

It is possible;

here is how Blenders new much faster obj exporter seems to handle PBR Textures in its mtl file.

struct MTLMaterial {
  MTLMaterial()
  {
    texture_maps.add(eMTLSyntaxElement::map_Kd, tex_map_XX("Base Color"));
    texture_maps.add(eMTLSyntaxElement::map_Ks, tex_map_XX("Specular"));
    texture_maps.add(eMTLSyntaxElement::map_Ns, tex_map_XX("Roughness"));
    texture_maps.add(eMTLSyntaxElement::map_d, tex_map_XX("Alpha"));
    texture_maps.add(eMTLSyntaxElement::map_refl, tex_map_XX("Metallic"));
    texture_maps.add(eMTLSyntaxElement::map_Ke, tex_map_XX("Emission"));
    texture_maps.add(eMTLSyntaxElement::map_Bump, tex_map_XX("Normal"));
  }

https://developer.blender.org/D11019