Questions about the GLTF vertice count

#1

Hi all! I was wondering about the vertices count of the meshes. The pipeline I’m involved in outputs the same topological mesh morphed to different body shapes then bound to skeleton and set to a different animations. Finally, blend shapes are individually added.

In Maya, all vert, triangle, edge, etc count is the same. but when I export using Maya2GLTF and check in the babylonjs viewer for instance the vertices count is off by ~2000 and most perplexing is that none of the exports have the same vertices count. Anyone know why this is? (edited)

#2

It’s difficult to point out the definite reason for that, only based on the description.

A wild guess would be that the exporter (or more generally, one step in a pipeline) detects that certain vertices end up at the same position (maybe within some epsilon), and collapses them into one vertex for optimization. But this seems a bit unlikely, because conversely, depending on whether multi-indexing is used at some point, one exporter step might have to actually duplicate vertices to disambiguate texture coordinates or normals.

(You said that the vertex count is “off by ~2000” - but does “off” mean that there are more or fewer vertices, and what is the total number of vertices?)

Maybe someone can analyze this when you provide some example file, maybe even just with some “dummy mesh”, where the effect can be observed.
(I’ll likely not be able to test this, except, maybe with one of these 30-day-trial versions of Maya…)