Obj file loader:create one mesh with multi-material got wrong

[fdeng]

Hi everyone,

In the obj file, when an object has multi-material, the obj file loader will create several meshes.

I want to only create one mesh with multi-material, but got the wrong result:

I attached the obj file and the new obj file loader I modified(objFileLoader_new.js ), can anybody help to have a look why it is wrong. It troubled me a whole day now.

obj.rar

[Guest]

Pinging @kcoley

[kcoley]

Hi @fdeng.  Unfortunately, multi-materials on a single mesh is currently not supported in Babylon.js.  The current way to get the obj to load would be to create multiple meshes with different material assignments. 

[fdeng]

@kcoley

What I want is not a really a single mesh, but a mesh with BABYLON.MultiMaterial, it will have multiple submesh.

my code is like:

                if (handledMesh.materials.length > 1) {
                    babylonMesh.subMeshes = [];
                    var multimat = new BABYLON.MultiMaterial("multi", scene);
                    babylonMesh.material = multimat;
                    for (var i = 0; i < handledMesh.materials.length; i++) {
                        var submat = materialsFromMTLFile.materials[handledMesh.materials];
                        multimat.subMaterials.push(submat);
                        var submesh = new BABYLON.SubMesh(i, 0, handledMesh.positions.length/3, handledMesh.spans[0], handledMesh.spans[1], babylonMesh);
                    }
                }
                else {
                    babylonMesh.material = materialsFromMTLFile.materials[handledMesh.materials[0]];
                }

You can have a look of my entire code in the attachment in the top post

[kcoley]

@fdeng, gotcha, multiple submeshes makes sense.  I'll take a look at your version.

[kcoley]

@fdeng I took a quick read-through and one thing that seems to be missing is adding the submesh to the your handledMesh array:

Something like this:

handledMesh.subMeshes.push(submesh);

 

This playground may be a good reference in getting MultiMaterials to work with multiple submeshes if you haven't seen this one yet.

https://www.babylonjs-playground.com/#28EUMN#21

 

Let me know if that helps.

[fdeng]

Hi @kcoley

It seems not the reason, when create a submesh like below, 

var submesh = new BABYLON.SubMesh(..., mesh);   

Actually the created submesh will be pushed to subMeshes array of the parent mesh automatically.

You can verify it in  this new PG:

https://www.babylonjs-playground.com/#28EUMN#24

I removed these push actions:

sphere.subMeshes.push(submesh1);

sphere.subMeshes.push(submesh2);

sphere.subMeshes.push(submesh3);

sphere.subMeshes.push(submesh4);

sphere.subMeshes.push(submesh5);

sphere.subMeshes.push(submesh6);