Feature: Support for encoding Quads about draco HOT 15 CLOSED

Our .obj decoder currently handles only triangular faces. We may add support for triangulation of more complex polygons later if there is sufficient demand. For now you would have to triangulate the model either in your modeling app or tools such as MeshLab.

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I have just met this problem too...

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I've added the request to our internal issue tracker. I'll post an update when there is any progress to report

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@ondys any update on this issue? Thanks!

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@bradrothenberg Actually yes. We have added support for quads internally and it should be pushed to public within this week. I'll update this issue when that happens. Note that the quads are not going to be preserved. The output is going to be a triangular mesh (quads are split into two triangles).

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Support for loading quad meshes has been added to the master branch. Let us know if you find any issues with this new feature. Thanks

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thanks @ondys !

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@ondys is there a way to preserve the original vertices & faces? & then we can handle the triangulation on our side (like for rendering etc)

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@bradrothenberg Preserving original quad faces is currently not supported. All our compression techniques currently work only on triangular meshes so the input has to be triangulated. We could possibly encode information about quads in a separate geometry attribute if that's something that would be acceptable (of course this would result in worse compression). Is there any reason why you cannot triangulate the mesh before it is encoded?

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@ondys I was thinking we could add an attribute to each face that is an index to a "surface" & then compress this? We are looking at using draco to compress mesh data in the CAD software we're building. Currently we support n-sided polygons for meshes:

so we can do things like generate ribs based on their edges:

When using n-sided meshes, we do triangulate each face for rendering & such, but we need to keep the association of each tri to each face in the mesh so that we can still do things like extract the edges of the n-sided faces...

Could we just add new attributes only to the triangular faces that are part of larger n-sided faces by calling:

mesh.SetAttribute(mesh.num_attributes()+1, std::move(newAttribute));

& the attribute would be a GENERIC geometry attribute ?

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@bradrothenberg Yes it should be possible to do it with a new generic attribute of type DT_INT32 where every point on a triangle would reference to its associated polygon id. The only thing I'm worried about is that this would not really compress that well. The compression can be improved if you apply some graph coloring algorithm to generate the polygon ids (i.e., use only a very few unique polygon ids for all faces while making sure that no two neighboring polygons share the same polygon id).

Ideally we would not actually need to store any polygon ids at all as all we need to store are the boundaries between the polygons and the ids can be generated implicitly on the decoder side .. this would require some changes to the framework though as Draco doesn't support implicit attributes yet.

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thanks @ondys !

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Are there any plans on support for this? Thank you.

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@tastnt Nothing new at this point. I would suggest anyone with this request to add it here so we can more accurately gauge the demand

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Closing due to inactivity.

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