I used this example Playground from the docs to merge two meshes together. I then added the following line to export the combined mesh as an STL file: var stlFile = BABYLON.STLExport.CreateSTL([mesh], true, mesh.id); However, when loading the exported STL into a CAD tool like Fusion 360, I get a “…

You might need to Implement your own mesh triangulation algorithm to ensure you keep a closed area. This would be a great addition to Babylon and a PR is welcome :slight_smile:

I see, I’m probably not capable of pulling this off on my own, but since this is for a commercial open-source project, I’d be more than happy to fund someone/somehow make a donation to BabylonJS in case anyone might be interested in digging into this and giving it a shot. :pray:

This would be a really nice addition, let s see if @PatrickRyan or @Evgeni_Popov know the same of some techniques in this space ?

@sebavan , I’m not familiar with the particular algorithms for boolean, tesselation, and remeshing that we could implement. What I can say is that traditionally the act of boolean operations on meshes for export to STL for 3D printing has fallen to MeshMixer. This is a free Autodesk app that does han…

You mentioned that the sphere alone also throws an error, while a box does not. Can you try with two box meshes merged? Both with and without union and let us know how it goes. I don’t think that it’s the STL file or exporter that is bugged, it could be some loose geometry in the sphere or some o…

:x: Complains with union: [Screenshot 2023-11-07 at 4.33.01 AM] :heavy_check_mark: Doesn’t complain with merging: [Screenshot 2023-11-07 at 4.35.01 AM] Reproduce: Babylon.js Playground Babylon.js playground is a live editor for Babylon.js WebGL and WebGPU 3D scenes …

The CSG version seems OK, it looks fine in some stl viewers I’ve tried, whereas it looks really strange in your screenshot… I’m not sure what the problem is with Fusion 360. Can you click on the warning and choose to repair the mesh, to see what Fusion does to make it work? Maybe that will give us …

it looks fine in some stl viewers I’ve tried, whereas it looks really strange in your screenshot… It also “looks” fine for me: [Screenshot 2023-11-08 at 5.43.50 AM] I was just hovering over the “Mesh is not closed” warning icon (:warning:) which highlights the problematic mesh regions in blue …

Thanks for this detailed report! The problem is not the export but the CSG operation. The problem is that we have no way of influencing what CSG produces, it’s a kind of black box. I suppose we’d need a “repair” step like in Fusion 360… This page lists a number of resources, it might be a good star…

The problem is that we have no way of influencing what CSG produces, it’s a kind of black box. Why is that? The subtract CSG code for example seems to be here , which seems to originate from csg.js . Note that this file hasn’t been maintained for 12 years. Perhaps there’s some room for improvement? …

STL export is buggy on merged/subtracted meshes

Bugs

WarinSpace_Game November 7, 2023, 2:37am 16

Complains with union:

Doesn’t complain with merging:

Reproduce:

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STL export is buggy on merged/subtracted meshes

Complains with union:

Doesn’t complain with merging:

Reproduce:

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