Obj+mtl model is loaded but is black

Questions
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1

the way our .mtl file is produced was changed recently, now our models appear as black.
here’s the code in a repo to show what I try.
the example is taken from the threejs examples, only files were change

what I already tried:
play with the lights, camera etc without success

tried following this advice:

but got an error ‘no multimaterials allowed’

this website was able to succesfuly convert to gltf: modelconverter.com
which was then succesfuly loaded in three.js editor with colors etc

2

Changing file format is not the answer.

Does the OBJ file have normals?

3

Changing the format was done to validate that it’s a code issue.
Regarding your question, how do I check for normals?

4

There are no vn definitions in your OBJ asset and thus no vertex normals. But you can compute them manually after loading like so:

object.traverse( function( child ) {

	if ( child.isMesh ) child.geometry.computeVertexNormals();

} );

Doing this in the three.js editor and then OBJ looks like so:

image
image1910×1962 808 KB

1 Like
5

1 - Open the obj file in any 3d editor.
2 - Open the obj file in any text editor and
See if you have lines starting with
a “vn some_number some_number some_number\n”
b “f some_number/some_number/some_number” or “f some_number//some_number”

(notice the slash f/2/2/2 or f 2//2)

f 40183/111824 40368/111857 40092/111823 from scene_mesh_decimated_textured.obj
f some_number/some_number => f vertex/uv/no normal

6

I would not use computeVertexNormals, better use a 3d editor. Doing normals is a matter of both science and art.

7

I would not say that. Normals are even sometimes generated in the shader on-the-fly. Using computeVertexNormals() seems to provide a proper result.

8

adding this to code results in a blank screen:

new OBJLoader(manager).setMaterials(materials).load(
    "/public/scene_mesh_decimated_textured.obj",
    function (object) {
      // object.position.y = -95;
      object.traverse(function (child) {
        if (child.isMesh) child.geometry.computeVertexNormals();
      });
      scene.add(object);
    },
    onProgress,
    onError
  );
9

computeVertexNormals does not account for seems nor face weight.

10

This is irrelevant for this use case.

Do you see any errors in the browser console?

11

@Mugen87
No errors in the console.

can you show me where to add your code in the threejs editor ?