Associating commenting annotations with 3D models #2421
Description
In all of the current TSG commenting annotation draft manifests the commenting annotation targets the scene with a selector to place it. The "position" attribute is then optionally used to adjust the displayed comment to avoid geometry, etc.
This makes sense and works well until you bring multiple models into a scene. It lacks a way to associate specific commenting annotations with the models they are describing. While some comments may be association-free, it's common that creators will want an annotation to move with a specific model when it moves, hide when that model hides, etc. We would need to be able to define this hierarchical relationship for viewer implementations to make use of it.
My original issue was how we could define this (apart from nested scenes, which seems complicated and could quickly devolve) but I see in the current draft spec that the commenting example now targets the model, which solves the association issue but complicates placement. If we are targeting the model, a selector would now require local coordinates instead of global, no? Or is the expectation that a target with selector is no longer how we position things and only the "position" attribute is used?