Workflow for cutting holes in geometry and preserving normals

I will try edge split, cheers.

I can solve it by creating a bevel with more than 1 segment, e.g. 3 and set the profile weight to 1.00 but of course this creates more geometry.

I will try edge split too but often avoid splitting as it breaks a water tight mesh.

Thanks for the help.

I will try that too, thanks.

Is 3DS Max better at this than Blender 2.8?

I know max has assignable smoothing groups that Blender does not and a Unify Normals tool but my max subs ran out so can’t compare the two.

With Blender 2.8 (edit mode, not the modifier) Edge split separates the edge by detaching it so if you split an edge around a quad then that quad face can be lifted off the mesh thus breaking the watertightness of a mesh. Also, when merging vertices in cleanup operations this will re-weld those loose edge vertices.

I think you may be referring to Mark Sharp and Clear Sharp features for editing edges which works with Normal Auto Smooth.
https://docs.blender.org/manual/en/2.80/modeling/meshes/editing/edges.html?

I just discovered there is also a mesh->Normals->Split command that enables custom normals shading (with Auto Smooth) but disables the Angle limit, this does not break vertices and has a companion modifier called “Normal Edit” and seems to be for game designers. I will give this a play with tomorrow
https://docs.blender.org/manual/en/2.80/modeling/meshes/structure.html#custom-split-normals

Control N is a 2.7 hotkey. I think it is now Recalculate Outside / Inside in 2.8 (via Alt+N) but that rarely helps when trying to fix normals that do not shade well in Verge, it does help if you are trying to create transparent materials I found.

As for the differences between Max and Blender, yes I see what you mean. Cheers.

Urgh, I give up. I have spent 5 days on this.

I think that the Verge3D / Blender 2.8 gltf 2.0 exporter is ignoring custom normals.

Workflow
1. Create a cylinder 01
2. Duplicate it and hide cylinder 02
3. Punch a hole in cylinder 01
4. This has normal issues like visible edge creases due to triangulation, quads etc and is expected at this point.
5. To fix that, transfer normals from Cyl 2 to Cyl 1 to it looks perfect. Various ways to do this, I use MESHmachine stashes but you can do it manually using Data Transfer modifier.

The object now has custom normals and looks clean in Eevee.

Results:
If I export this using Verge3D gltf exporter the custom normals are ignored and the resulting mesh is poor.

If I import the Blend file into Unity, build a simple webgl project and compile it, the custom normals are preserved and the model looks as it should.

possible conclusions:
Blender or Verge’s version of the exporter is ignoring custom (vertex) normals.
Unity preserves custom normals either via FBX conversion or through its own import algorithms and shows the webgl as it looks in Blender.

Unity model import options:
Mesh compression off
Optimize mesh off
Keep quads on
Weld vertices on
Normals: Import
Normals mode: Area and angle weighted
Smoothness Source: Prefer smoothing groups
Tangents: Calculate Mikktspace

This is a shame as fixing normals in Blender just for Verge takes ages and requires lots of additional edge loops and sneak peaks as you work.

I have noticed that there are quite a few Blender bug reports about custom normals in early 2.8 branches of the Blender gLTF 2.0 exporter and these are still present when using the Blender exporter instead of Verge3D. I thought I could get around this by baking the normal maps but Blender Cycles would not bake the custom normals either.

Could you please try exporting the attached Blend file to FBX/Max and then export via 3DS Max to see if it has the same shading issues?

Thanks

I posted an updated solution to this issue but it is not showing in the forum?

Anyway, rather than triangulate the mesh which is destructive, just apply a Triangulate modifier and tick “Keep Normals” to solve custom normals and provide a WebGL WYSIWYG of the mesh between Blender and Verge3D. No need to apply it. Works great.