Using MultiMaterials with ObjectLoader

[arturitu]

When I tried to import from Blender meshes from a Blender scene with multiple materials don't work correctly with ObjectLoader. ( I think is because json has't assign correctly the material to the object, it uses a single uuid. (this happens in previous versions of three.js & blender exporter ( It is nothing new of this r73 version ) ).

I can only use MultipleMaterial with JSONLoader ( although with the R73 I have to remove 'DbgColor' & 'colorAmbient' info from .json file ) but in this case I need a json flie for every object.

Here an example > http://unboring.net/lab/7415/
And the source files > http://unboring.net/lab/7415/7415.zip

[mrdoob]

I'll take a look. Thanks for the files!

[mrdoob]

So seems like this is a Blender exporter issue (ping @repsac).

However, I've added materialIndex support to Geometry.toJSON() 😶 and robustified MultiMaterial.toJSON(), so... as a temporal workaround, you should be able to drag the file in the editor and export from there.

[arturitu]

Thanks for all!

I have tried to drag into the r74dev editor the .obj file ( converted directly from ringScene.blend file ) but only appears one material. I suppose that I'm missing something, but don't worry, I'll wait for the fix for the next work... or I'll be back to try with the editor again.

[mrdoob]

No no. Drag the .json file 😊

[PaulSos]

We are running into the same problem. We want to use multiple materials on an object in a scene with more than 1 object. When exporting the scene only 1 material per object is applied. We are using the ObjectLoader because JSONLoader is deprecated.

[mrdoob]

Can you try the editor in the dev branch?

[arturitu]

With the editor in the dev branch, when I drag the .json file exported directly from Blender, only appears one of the materials. I am exporting in a wrong way?

• Files used ( .blend & .json ) > http://unboring.net/lab/7415_fixed/ringScene.zip
• Screenshot >

[mrdoob]

Ok. Took a while to figure out but the issue is that the Blender exporter doesn't export MeshFaceMaterial/MultiMaterial. The ObjectLoader neither knows how to handle the materials that JSONLoader produce. We definitely need to clean this up.

In the meantime, your best bet is to use vertex colors instead (you'll have to duplicate the vertices).

[PaulSos]

After some testing we discovered when using face materials option (from Shading group) in the exporter materials are saved in the geometries. But object loader ignores them and uses only materials from root node.

What do you mean with duplicate the vertices? Do we only have to enable the vertex colors option while exporting?

[mrdoob]

What do you mean with duplicate the vertices? Do we only have to enable the vertex colors option while exporting?

In @arturitu case, he is coloring faces, so he will have to duplicate vertices if we wants to use vertex colors.

[PaulSos]

Ahh ok, so thanks a lot.

Maybe you also got an Idea for our Problem too?
We want to Build a City. When we texture the objects, we only can use one material per object at the moment, cause when we export the scene to a .json file, only one Material is linked.
Is there maybe another Way to texture Objects, using more then one texture or material and export it sucessful to a json file?!

[mrdoob]

You should research "texture atlas".

[satori99]

I started playing with the new ability to use BufferGeometry groups with MultiMaterials and noticed that the ObjectLoader was ignoring the group.materialIndex property in Object Format 4 JSON files.

I submitted a PR to parse the property #7552