Smooth edge for glb models

Questions
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1

Hello,

I have an imported glb file, the edges are hard. I’ve looked it up and found that glb separate the vertices when exporting (using Blender), so is there a way to smooth edges for a glb file?

Currently I’m trying to merge vertices then smooth normals, but I can’t figure that’s out! I’m using BufferGeometryUtils to .mergeVertices(geometry) then computeVertexNormals() but I’m not getting anywhere!

Thanks.

2

I’m in the same boat, this does not work any more (I think it used to, so why not now?) so I had to do this instead.

1 Like
3

So it never did. What used to work was the other geometry class method.

4

For smoothing by normal vectors at vertices → there is a topic in this forum about something similar and the solution was to smooth the object in Blender and reexport the model:

Striped shadows on OBJ/MTL model

Off-topic: I like @makc3d’s 4-points controls. I remember in the past I wanted to do something similar for one AR project, but I messed the math up and failed. I wish I knew this lib two years ago.

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5

opencv :sweat_smile: (well, there are like 10 different ways to do it, you basically only need to slice a pyramid by a plane. if you messed up one of them, you could always try another)

2 Likes
6

@makc3d yea I think this does not work anymore!

7

Thanks, I’ll check it out! for now I just switched to fbx. my concern at the moment is the file size, but fortunately when I switched the size didn’t get impacted that much!

8

@PavelBoytchev as it say in the title, they are using OBJ not glTF, and I think the problem was just not smoothing the mesh correctly from the 3D tool. I’ll look more into it.

9

turns out I was wrong here, it kinda did. e.g. this

        function fixDuckingNormals( o ) {
            if( o.geometry ) {
                delete o.geometry.attributes.normal; // <== important! lol
                o.geometry = mergeVertices( o.geometry );
                o.geometry.computeVertexNormals();
            }
        }

worked for me. but that;s because the duck has very special uv map - a single island connecting to itself on the other (mirrored) side - so it had no seams. any “normal” uv map will generate a ton of seams like that.

1 Like
10

Thanks! I’ll try it.

11

@makc3d So I’ve tried your solution and it gives an error saying mergeVertices is not defined …

But here’s the odd thing, I’ve exported a simple low poly sphere as glb from blender with smooth edges, after adding it, it runs smooth! without doing anything … the mesh I’m using is a photogrammetry scan but I edit it in blender, I’ll look it up some other time.
but thanks for your help

12

oh that the one from BufferGeometryUtils:

        import { mergeVertices } from 'https://threejs.org/examples/jsm/utils/BufferGeometryUtils.js'

(adjust the path to your threejs)

13

well of course, if you export good normals layer it just works.