Add a Selection Gizmo

[schlegelp]

This is a draft PR for adding a selection gizmo (see #745).

python3 examples/feature_demo/selection_helper.py

Screen.Recording.2024-05-08.at.15.47.16.mov

Potential TODOs:

• make sure this also works well in 3D
• explore the possibility of a 3D selection gizmo (first click + drag creates 2d box, second click extends to 3d box)
• allow multiple modifiers for starting the drag (e.g. shift-control click to start dragging)
• handle WorldObjects in SelectionGizmo.is_inside
• variations of the basic gizmo:
  • lasso selection (this should be fairly easy)
  • draggable selection rectangles

I'm aware that this might be out of the scope for pygfx itself as you may not want to weigh yourself down with having to maintain too many non-essential bits and pieces. If that's the case, no hard feeling! Also no worries if this implementation is going in the wrong direction.

Have a look & let me know what you think.

[kushalkolar]

I think a clear_handlers method would help with garbage collection

[kushalkolar]

true I'm a bit confused by this as well

[kushalkolar]

What do you think about drawing a rectangle (or arbitrary shape with lasso) and allowing it to stay in the scene so it can be moved around? (That could be another selection tool class, I'm just thinking if it'd be easy to do here 🤔 )

[schlegelp]

What do you think about drawing a rectangle (or arbitrary shape with lasso) and allowing it to stay in the scene so it can be moved around? (That could be another selection tool, I'm just to think if it'd be easy to do here 🤔 )

Certainly possible. I've added it to the potential TODOs.

[kushalkolar]

A few other things I can think of are resize handlers and a circular/elliptical selection tool. Anyways we can chat more on Friday. This actually helps us a lot with the fastplotlib roadmap!