Expose a CursorPosition resource

[alice-i-cecile]

What problem does this solve or what need does it fill?

Knowing where your mouse is is useful and should be ergonomic.

What solution would you like?

Store and update a CursorPosition resource, which reads from the Window resource to store an Option<Vec2> representing the physical position of the mouse (or other cursor).

What alternative(s) have you considered?

Compute this manually every time it's needed.

Additional context

This will be impacted by #4530, which will move where this data is stored.

Better APIs to convert between world space and screen space coordinates will make this functionality even more useful; we should add methods on MousePosition to do this once those are established.

[alice-i-cecile]

We probably want to also record which window the mouse position is associated with, and iterate through all of the windows to check if it's on any of the open windows.

[mockersf]

right now, such a resource would be equivalent to the resources Windows and getting windows.primary().cursor_position(). I'm not sure it's worth it before #4530

[alice-i-cecile]

The ergonomics and discoverability of that solution are really poor though.

Every time i need to do these or to teach someone how to do this I need to link to the Cheatbook page.

This solution would also be robust to those changes, which would provide a nicer migration path.

[Edwox]

Hi! I was just wondering if this issue has been resolved or not?

[alice-i-cecile]

Has not been resolved, but Francois's workaround still works :) I'd be happy to review a PR that tackled this before #4530, as that work is shockingly complex.

[mockersf]

There was a first attempt in #5079 and people decided to wait for #4530 in it

[Edwox]

Ok, so the best option would probably be to wait for #4530 to be resolved. I have never contributed before, but If there is anything that I could possibly try and improve upon then I would like to give it a try.

[wilk10]

#4530 has been closed by #5589 . Can this issue also be closed now?

[alice-i-cecile]

I don't think this can be closed: instead, it's no longer blocked.

[dennisorlando]

right now, such a resource would be equivalent to the resources Windows and getting windows.primary().cursor_position(). I'm not sure it's worth it before #4530

I'm currently implementing "ExtractResource" for a "MousePosition" struct, but given that the "Windows" resource is no longer a resource, I cannot put "Windows" as the associated type of the ExtractResource trait anymore which kind of hurts my feelings (I'm following #6550 to fiddle with compute shaders)
Thus, a cursorposition resource would be useful, even if just as really simple and trivial plugin that you can add to the app like "CursorPositionResourcePlugin", as ugly as that might sound :,)