The hand-controls gives tracked hands (using a prescribed model) with animated
gestures. It wraps the vive-controls component, which wraps the
tracked-controls component. It adds additional events, semantically
named, and handles hand animations.
The entity will track the left hand controller.
The entity will track the right hand controller.
Grip buttons pressed. Hand is closed.
Grip buttons released. Hand is open.
Trigger button pressed. Index finger pointing up.
Trigger button released. Index finger pointing down.