Add a node to unproject 3D position to 2D

[timothyqiu]

It's trivial to add something like this in _process():

var cam := get_viewport().get_camera()
var pos := get_parent().global_translation
rect_position = cam.unproject_position(pos)

I think it could be helpful to add a Unprojector2D that extends Node2D. When its parent is a Node3D, it updates its position the match the parent's unprojected position.

[Calinou]

I remember seeing a proposal about adding a new RemoteTransform node to cross the boundary between 2D and 3D. That said, I don't think it's a common use case enough to warrant being a core feature – this can be done with an add-on.

[timothyqiu]

The use case is like 3D Waypoints Demo. It's not for 2D GUI in 3D, but matching 2D annotation elements for 3D objects like health bars, name plates, and action key prompts.

Viewports have a performance cost. So instead of using a billboard & fixed size Sprite3D, it's more acceptable to use plain 2D. Label3D solved this problem for texts, but the problem remains when other Controls are needed.

[Zireael07]

Counter argument: Not everything has to be a node, they have a perf cost

[timothyqiu]

I remember in a multiple-script-per-node issue/proposal and in a virtual folder in tree proposal, it's recommended to add extra nodes to the tree instead since it has no performance cost.