Interaction axis r support?

[peteruithoven]

Feature Proposal

For Cartesian charts we can set the interaction to a whole axis. So when there is a smaller bar we can still easily access the tooltip. Example:

This doesn't seem so easy for polar charts:

I'd like something similar for polar charts, where no matter how close to the middle we hover we always get a tooltip. I was expecting there to be a option to set interaction.axis to r (radial) for example.

I can set the intersect to false, but larger wedges will almost always be nearer.
Setting the mode to index and the intersect to false leads to unexpected interaction areas.

Feature Use Case

We have polar charts where in some cases the wedges are very small. We still would want people to easily access the tooltips per wedge.
A simple example that illustrates this challenge:
https://codepen.io/peteruithoven/pen/rNzJLaP

Possible Implementation

An r (radial) option for interaction.axis seems like a good solution? Consistent with Cartesian charts.

[peteruithoven]

The interesting bits are here: https://github.com/chartjs/Chart.js/blob/67c5a851445b3d25a9ceec344404b4ab65ed8ff1/src/core/core.interaction.js

It's currently all based on x and/or y positions, we'd probably need to add something like an angle and support detecting the nearest based on that angle?