Feature request: shape keys/morphing support

[ArnCarveris]

Hi,
I haven't found suitable job class for make facial expressions and etc (https://www.youtube.com/watch?v=ypRhJAfJXAc),
maybe I miss some building blocks for that?

How hard is to make such feature?

[guillaumeblanc]

Hi,

there's no vertex morphig implementation in ozz, which is how I understand your request. Of course it's interesting, but I think working on vertices is a different domain (compared to working on joints), in terms of data structures, compression, optimizations... I would also suspect that a lot of that work should be done on the GPU.

Have you considered animating facial expressions with joints ?

Cheers,
Guillaume

[infosia]

Sorry for interrupting but I'm interested in this too. I'm guessing ozz may be able to support weights animation channel in order to support morph target animation in glTF, I expect it just consists of float array weights and can be treated similar way that gltf2ozz.cc does for rotation/translation/scale.

maybe related:

• https://github.com/guillaumeblanc/ozz-animation/blob/master/src/animation/offline/gltf/gltf2ozz.cc#L814
• https://github.com/syoyo/tinygltf/blob/master/tiny_gltf.h#L530

[JSandusky]

Just importing the weight tracks should be sufficient. I feel this is off into the realm of things like phase-matching (which requires no changes, just ratio management and external data for where the phases are) where the onus is on the end-user and the only real requisite Ozz-side is to grab those weight tracks if they exist in the converter tools.

[guillaumeblanc]

Hi,

If it's not vertex but animation morphing, then yes supporting weighted animations should help and be doable. To be sure we talk about the same thing, could you give a link to gltf specs that describes the weight animation channel? Is that it ?

Ozz importer/converter already support animated float tracks. It is exposed via the "tracks" parameter in *2ozz tools. It outputs ozz::animation::Tracks that can be sampled at run time. The implementation is only available in fbx2ozz (and inspired by fbx node properties), as I couldn't find any similar feature on gltf specs. But the importer supports them, and "only" requires to overload track related functions.

• Would gltf spec match with the way ozz importer identify tracks (ozz identifies properties on nodes, with a ppt name) ?
• Is there an open gltf model that demonstrate the feature ?
• The feature is up for grab. I'm glab to help if anyone is interested.

Cheers,
Guillaume

[ArnCarveris]

Hi @guillaumeblanc there is example: https://github.com/KhronosGroup/glTF-Sample-Models/tree/master/2.0/AnimatedMorphCube

[infosia]

• Yes, what I was talking about is weights that's stored in glTF animation channel
• There is tutorial from Khronos- A Simple Morph Target
• Sample models - SimpleMorph, AnimatedMorphCube

So I expect morph weights can be expressed as a float track in ozz, but it may be a bit tricky for ozz because glTF stores arbitrary number of morph targets, which equals number of targets in the mesh's primitive.

Animation output accessor has following layout:

n - number of weights (equals number of targets)
c - number of keyframes

[W1, W2, ..., Wn] * c

Maybe this discussion thread would help understand the spec.