Assimp format (fbx, dae, ...) provide empty metadata

[mwestphal]

Describe the bug
F3D support many formats through the assimp plugin, however the meta data provided for these formats is empty

To Reproduce
Steps to reproduce the behavior:

1. Open the file using f3d --no-config -m 16bit.fbx

Expected behavior
Meta data should contain information

System Information:

• OS: Any
• GPU and GPU driver: Ant

F3D Information
Paste the content of f3d --version: 3.0.0

Additional context
F3D uses vtkF3DMetaImporter::GetMetaDataDescription() to recover that information, something must be going wrong there.

[mwestphal]

Point sprites also do not work with assimp, I think this is related.

[exbluesbreaker]

I will work on this issue :)

[exbluesbreaker]

I haven't found a fix yet, but I believe I've identified the root cause.

To gather all necessary information, F3D first requires actors, which it retrieves using:

vtkActorCollection* actorCollection = importer->GetImportedActors();

in bool vtkF3DMetaImporter::Update().

The issue is that vtkF3DAssimpImporter does not update the field accessed by GetImportedActors. Instead, it performs the following operation:

void vtkF3DAssimpImporter::ImportActors(vtkRenderer* renderer)
{
  this->Internals->ImportRoot(renderer);
}

This means that it updates Internals, which maintains its own structures for tracking actors. As a result, this->Internals is aware of the actors, but this itself is not, leading to "invisible" actors.

Probably vtkF3DAssimpImporter::ImportActors should also somehow update its own ActorCollection together with Internals but I do not have an implementation yet.

[mwestphal]

Yes, you are absolutely right. The importer needs to be reworked to populate the actor collection.

[exbluesbreaker]

I tried adding copying of data from internals into importer itself. Pull request is #2058

Now you can see this with 16bit.fbx, hope it is correct:

[mwestphal]

Fixed by #2058