Infer face_normals=True/False according to .use_smooth attribute of polygons

Hi folks! I believe, it would be really helpful to toggle the export of face/vertex normals naturally by using Shade smooth or Shade flat options in Blender. It can be inferred via .use_smooth property of faces on export stage.

If that makes sense, I can draft a PR.

Hello,

The add-on should already support exporting both flat & smooth shaded meshes by setting Mitsuba's face_normals flag as you can see below.

mitsuba-blender/mitsuba-blender/io/exporter/geometry.py

Lines 139 to 141 in 2b9365f

    
           # Add flat shading flag if needed 
        
           if not mts_mesh.has_vertex_normals(): 
        
               params["face_normals"] = True

If this does not do what you expect, can you please explain in more details what issue you are experiencing and how to reproduce it ? Also, can you indicate which version of Blender & the add-on you are testing this with ?

Thank you!

Thank you for the prompt reply!

All shapes created in Blender have vertex normals. For imported meshes, afaik Blender auto-generates them if they were not present. However, whether to use them or not is determined by toggling Shade Smooth / Shade Flat as shown below.

That would be great if Mitsuba add-on reacted to this toggling, or if there was a separate option to give preference to face normals and ignore vertex ones during export.

Which version of Blender are you using? This works with Blender 2.93 but something may have changed in later versions.

I am using Blender 2.93 and current master branch for the add-on

Oh, I actually double-checked with the sphere and it worked for me too... I did not understand yet why, but worked :)

Never mind, sorry for raising the issue and thank you for looking into that!

	# Add flat shading flag if needed
	if not mts_mesh.has_vertex_normals():
	params["face_normals"] = True