This PR exposes skeletal joint entities to the frontend hierarchy,
allowing the user to pose rigged models by selecting the joints and
transforming them.
Additionally, entity-type information (e.g., Mesh, Skeleton, Bone,
Light, etc.) has been added to the data structure passed to the
frontend, which is rendered with icons in the tree view.
This PR adds a WIP timeline UI for animating elements in the scene.
### Implemented Features
* The timeline can be panned with MMB and zoomed with Ctrl + Mouse Wheel
* The timeline can be "scrubbed" by dragging the red "play-head" with
LMB
* The timeline sidebar (displaying the list of tracks) can be resized by
dragging on the edge of the sidebar
* Keyframes can be added by pressing the "Add Keyframe" CTA in the UI
* Keyframes can be selected for editing by clicking the diamond-shaped
markers in the timeline
* Selected entities (including but not limited to keyframes) can be
deleted by pressing the "Delete" key
* Keyframes can be moved temporally by dragging the diamond-shaped
markers in the timeline
### Known issues
* Zooming the timeline in too far results in a soft-lock
* When zooming the timeline, the "transform origin" is currently
centered on the `00:00` timestamp. For ease of use, it should center on
the mouse cursor position instead.
* The timeline track-list is currently hard-coded to list the Camera and
Camera Target. Clicking on these entries currently serves no useful
purpose and may result in a crash.
* Keyframe markers in the timeline are not currently associated with
entries in the track-list and simply appear vertically centered in the
timeline view.
* Added keyframes currently record the position and orientation of the
scene camera when added, and are rendered in the world with debug
visualizations, but serve no useful purpose. Some design work is needed
(both user-experience and architectural) to decide on a workflow for
actually animating scene elements.
* Entity deletion cannot currently be undone/redone
This PR adds `cargo fmt -- --check`, `nx lint ...` and `nx test ...` as
GitHub Actions. This will cause future PRs to automatically fail when
formatting issues, Clippy warnings, or test failures are present in the
changed code.
This PR adds support for Mixamo FBX imports (via backend conversion to
glTF/glB) and some miscellaneous improvements to the animation systems.
### User-facing improvements
* Retargeting math has been fixed to eliminate jittering issues
* Retargeter can now handle animated bone translations when present
(generally this is only used for root motion)
### Housekeeping / Code improvements
* Animation-related components and system logic have been moved to a
dedicated `anim` module and `AnimPlugin`
* Retargeting stuff has been moved from the `bvh` module to
`anim::retargeting`
* Component-based solution for marking an entity as an animation
retargeting source makes it easy to extend the retargeting functionality
to new types of source animations
### Limitations
Currently the code assumes that there will be at most one animation
source at a time. That single animation (if present) will be retargeted
to all other skeletons in the scene. A component-based solution for
directing a specific target skeleton to use a specific source animation
is possible, but will require some additional consideration around the
implementation design for the read-only "viewer" modes.
### Test animations:
* Hip-Hop Dancing (Mixamo): ?mode=viewer&mixamo=mocap/hip-hop-dancing.gltf
* Shuffle (MocapNET): ?mode=viewer&bvh=mocap/shuffle.bvh
* Scott (MocapNET): ?mode=viewer&bvh=mocap/scott.bvh
* Scott 1 (MocapNET): ?mode=viewer&bvh=mocap/scott1.bvh
Lee-Orr