How would we get input, e.g. mouse or touch?

• Qt3D provides object picking. However this does not really work as-is together with our layer concept. With 3DS we effectively have multiple scenes, each with its own size and camera. These are rendered offscreen and then composed together in a pre-defined order, applying an arbitrary transform to each texture (a translation in practice but could be a rotation as well in theory). Picking should be aware of this somehow: it should be able to filter the scene (a'la LayerFilter) and take the compositor ordering and transforms into account somehow.

• The input system of Qt3D is not necessarily acceptable - ideally we should be able to feed the picking system with events of our own.

• Special cases, like mouse input for the profile UI itself is handled separately (by getting events directly from the QWindow), and is already in place.