Exporting Alembic files to Sketchfab

Have you spent countless hours trying to figure out why your Alembic file isn’t importing properly in Sketchfab? Then this is for you. :wink:

Why Alembic in the first place?

Unlike other formats who can only export whole objects moving and rotating each frame, the Alembic format can export deforming meshes where each vertex can be transformed, or even removed (though removing or adding vertices will destroy your UVs). That makes Alembic perfect for exporting moving water, clouds, or any deforming geometry.

Optimising your scene

If you tried exporting .abc files before you would know that Alembic files are HUGE, So if you want to reduce file size to be able to upload to Sketchfab, make your scene viewable on mobile, you would have to optimize that scene.

One absolutely essential step for exporting to Sketchfab is to make sure each object has only one material assigned to it, that means joining all static objects with the same material into one object (to avoid reassigning textures for each object and to also make it easier for realtime rendering) and separating the parts of objects with separate materials, that’s because Sketchfab currently applies one material per object despite of what you have set up in your scene.

Keep in mind Sketchfab can only support up to a 100 materials in one scene, which means you have to have less than a hundred separate objects in your scene for Alembic.

Another crucial step is to only export the objects you need in that scene, that means no Empties, cameras, lights, or hidden objects. I would recommend using the “selected objects only” setting which you can find by toggling the gear icon here:

Screenshot (87) arrow
P.S. Check “Face Sets” to keep material data for use in other programs.

To optimize even further you can lower the poly-count of deforming objects.
less moving vertices = less data and lower file size

Uploading to Sketchfab

Packing the file and textures is fairly simple, just pack them in an archive! I personally find that packing Alembic files in a .rar archive can dramatically reduce file size. Doesn’t really need that bold of a title but it’s very helpful when trying to be under the file upload limit.

So here is a summary of all you need to know:

  • One material per object
  • Less objects, less trouble (100 Max)
  • Only export rendered objects
  • Lower vertex count for deforming objects
  • Gear icon for export settings
  • RAR files are great!

Here is an example scene I made in-which I figured out all this stuff, also counts as shameless self-promotion:

1,140 Objects/materials :arrow_right: 41
185 MB :arrow_right: 88MB

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