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Content pipeline tools for optimizing glTF assets. :globe_with_meridians:

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Draco compression breaks EXT_mesh_features and EXT_structural metadata

balazsdukai opened this issue · comments

commented

I'm trying to compress gltf files with metadata for 3D Tiles v1.1 (EXT_mesh_features and EXT_structural metadata extensions).
The compression does happen and the output is a valid file (using gltf-validator), but Cesium does not load the compressed glb-s anymore.
I've seen #616 , so I thought that the compression is compatible with these two extensions.

The command gltf-pipeline -i input.glb -o output.glb -d. Also tried with --keepUnusedElements, but the result is the same.

commented

I tried to test this, with different models (and even created a new model that is similar to the FeatureIdAttributeAndPropertyTable model, but with more complex geometry), but could not reproduce the issue. I still don't know what exactly the conditions are for Draco to modify the indices.

If you could provide one of the input models (i.e. if it can be shared and has a "reasonable" size in its uncompressed form), then I could give it a try.

Otherwise, you might want to try to add the --draco.compressionLevel=0 parameter to the command line.

(Edited to remove some invalid guesses and cross-references)

commented

Hi, thanks for responding. In the meantime we implemented our own procedure for compression, using gltfpack as a library and we cannot output uncompressed files anymore. I should have uploaded a sample file right at the beginning, sorry.
As far as I'm concerned, this issue could be closed, especially if you are not able to reproduce it. It might be that our gltf writer was writing the extended gltf in a way that was not fully valid or not fully handled by the gltf-pipeline. It's hard to say, since there is no validator for these two extensions.

commented

When it's not possible to reproduce the issue (and the compression in general worked for the test models that I tried), then there's probably no need to keep this open. If someone encounters an example that uses these extensions and that cannot be compressed with Draco, then this may be reopened (or tracked in a new issue).