Display specific values of isosurfaces

[christeefy]

The IsoSurface trace has a surface argument which allows you to customize the number of surfaces shown (defaults to 2 for isomin and isomax). Specifying more than 2 gives you additional isosurfaces evenly-interpolated.

It would be nice to be able to control the specific values of additional isosurfaces — for example isomin=0, isomax=50 and additional isosurfaces at values 20 and 35.

Perhaps plotly.graph_objs.isosurface.Surface can have an additional values parameter that's mutually-exclusive to count.

The invocation using the example above would look something like:

Surface(values=[0, 20, 35, 50])  # Inclusion of `isomin` and `isomax` TBD

[gvwilson]

Thanks for the suggestion @christeefy - I agree it would be useful, but we're unlikely to get to it any time soon. We'd be happy to review a community PR - thanks @gvwilson

[christeefy]

Happy to contribute, though it'll take me a while to get to it on my current schedule + the surface area of changes involved in this repo and Plotly.js.

Thanks!