…to avoid re-processing timeline info
- move generating animation to first thing in a frame, and notifying
about timeline changes to last, to ensure that it happens before the
time updates
- re-generate the animation tweens whenever you start playing or
manually seek a new time in the timeline to prevent inconsistencies
This PR adds an initial animation timeline.
---------
Co-authored-by: Brandon Thomas <echelon@gmail.com>
Co-authored-by: Danny McGee <dannymcgee@gmail.com>
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
Lee-Orr