'Export Scene' (glTF) not writing surface normals

ParaView Support
1

Hi ParaViewers,

I’m trying to export glTF files representing a polygonal mesh for each time step in a simulation. As far as I can tell, Export Scene is the only way to use the glTF writer.

However, it is not writing my Normals array required for smooth shading with other graphics libraries.

Desired Appearance:

image
image1044×1167 88.3 KB

What I’m getting:

image
image1118×1053 40.3 KB

I observe the same behavior using Export Scene with .vtp format as well, but not when I do Save Data as .obj or .ply (but these are “legacy” exchange formats, I’d really prefer to use glTF)

Steps to reproduce with Paraview 5.12.0, Windows 11:

  1. Download sample red blood cell dataset from Argonne tutorial:

https://web.cels.anl.gov/projects/alcf_vis_internal/MISC/BLOODFLOW_TUTORIAL_DATA.tar.gz

  1. Load all .vtp and .vtu time series

  2. hide particles.vtu

  3. Export Scene → choose glTF

  4. select Save Normal when the dialog box opens:
    gltf_export_dialog

  5. open resulting glTF file and observe missing Normals array

2

Hi @inealey ,

Thanks for this detailed report! It looks indeed like a limitation of the current implementation.

We have a global ticket about gltf support in ParaView, feel free to comment also there: https://gitlab.kitware.com/paraview/paraview/-/issues/22446