Add functionality to draw a line (MET) at a given eta/phi

[EdwardMoyse]

This is a request from ATLAS - the reason is that often the missing energy used in analysis is not the same as the missing energy calculated during reconstruction, so it often does not look correct to analysts.

Since this is expected to be used for Missing energy (MET), one option would be to add it here:

However I think this might be technically difficult. So another option would be to consider it a type of guideline, and add it to the bottom menu? If so, we would need to input the direction, length, colour and draw style

cc @Somya-Bansal159

[NirvedMishra]

Is this still open, can I work on this @EdwardMoyse

[EdwardMoyse]

Please feel free to!

[vishrutharavi]

Hi @EdwardMoyse, is this issue still open? I’d like to work on this

[EdwardMoyse]

Sure! Please go ahead

[amanpandey2587]

Hi @EdwardMoyse ,is this issue still open since no PR has been raised ?.
If yes please assign this to me so that I could start working on it.
Thanks.

[DhanashreePetare]

I would like to work on the issue @EdwardMoyse, request to assign, if its still open.

[DhanashreePetare]

@EdwardMoyse

I have a few doubts :

1. Should I implement Option 2 (guideline in bottom menu) since you mentioned Option 1 might be technically difficult?
2. Should input be eta/phi (as in title), Cartesian (etx, ety), or both?
3. Should this create a separate collection or overlay on existing MissingEnergy?
4. Can users draw multiple custom MET lines or just one?
5. What draw styles are needed beyond dashed/solid (e.g., arrow)?
6. Should it go in an existing menu section or create a new "Custom Objects" section?

I'm leaning toward Option 2 as it seems more straightforward. Please let me know your preferences so I can implement it correctly.