Show warnings for common issues after successful export

[donmccurdy]

Is your feature request related to a problem? Please describe.

There are many cases where the export doesn't fail completely, but something isn't exported quite the way the user might have expected. For example, tangents weren't computed because the mesh wasn't triangulated, or a material wasn't configured in a way the exporter understands. For many of these issues, it's not easy for the end-user to diagnose the problem.

Describe the solution you'd like

As pointed out by @scurest (https://github.com/KhronosGroup/glTF-Blender-IO/issues/172#issuecomment-656454435), it's possible to display warnings after the export completes, and the FBX addon already uses this functionality. We should do the same for the cases above, and probably others.

Describe alternatives you've considered

For severe issues export can fail entirely, but we don't want that to happen when it can be reasonably avoided.

[stom66]

+1 for this, having just lost a day to figuring out why normals were not being properly exported! I took would like to see a similar warning/tooltip as the FBX exporter.

[Ziflin]

I just lost 2 hours as well trying to figure out why tangents weren't being exported on one of 5 objects that I exported. Please add the warning for this as otherwise we silently think all our meshes export properly when they did not. I believe there was even a patch to add the tangent warning here.

The above issue was raised almost 4 years ago, so it would be awesome if the hard triangulation option was added to the exporter, but this warning should certainly be easy enough to add to save wasted time and to avoid bad exports.

[effs]

One year later, and I just ran into this problem. (For some reason didn't find this thread trying to solve it, either.)

Added #1912 since GLTF doesn't actually support quads.

Keywords: export missing tangent