This PR contains improvements to the 3D scatter viewer from @victoriaono and myself. While we had previously opened #16, I've decided to split that into multiple PRs that each deal with changes to a specific exporter, just to keep things from getting unwieldy. This PR contains the 3D scatter-specific changes from #16, as well as some additional changes.

The features added to the 3D scatter viewer are:

Support for error bars
Support for vectors, via Plotly's cone traces
Support for point size scaling
The exported Plotly file now respects glue's color settings (foreground/background)
- This works fine, but will be easier to test out once https://github.com/glue-viz/glue-vispy-viewers/pull/372 has been merged in
Respect whether or not a user has axes visible in glue

There are a few issues, as well as a few choices that I think are worth mentioning.

As far as I can tell, Plotly doesn't show anything outside of the bounding box. This is different than the glue behavior, but unless I'm missing something re:Plotly functionality, I don't see what we can do about that.
As mentioned above, we can now support vectors using Plotly's cone traces. However, there are a few issues that pop up due to differences between glue and Plotly.
- Plotly offers a colorscale option for cones, but the colorscale is used for mapping colors to cones according to their norm. That's not really what we want, since glue gives users the option to set the colormap based on any attribute. Thus for colormapped layers, a separate cone trace is created, with a constant colorscale of the appropriate color, for each element of the data set.
- Aside from the colorscale issues, Plotly does its own internal scaling (in addition to the sizeref parameter that can be passed to a Cone trace) based on "the minimum 'time' to travel across two successive x/y/z positions at the average velocity of those two successive positions" - see the description of the sizeref parameter here. In my testing, this parameter can get really small if there are cones close together. Since we don't seem to be able to change this (see issue 3613 over in the plotly repo), I've opted to make each cone its own trace for fixed-color layers as well.
- In both of these cases, to give the illusion to the user that we are creating one cone trace per layer, I've grouped all of the cones into one legend group, and only displayed the legend for the first item. I've opted to include the cones in the legend so that the user can turn them on/off in the exported Plotly file.
- With the cone's center anchored to the point, the underlying data points are completely obscured, which makes seeing hover info impossible (even in the other configurations, mousing exactly to the data point can be annoying). Thus, I've attached the relevant hover info and text to each cone as well.

To warn users that the Plotly output may differ from what they see in glue, a warning message is displayed before exporting, which is attached to the (new) setting SHOW_WARN_PLOTLY_3D_GRAPHICS_DIFFERENT. Personally I think it's better to show one catch-all "things might be different" message rather than separate messages for each component that might differ (vectors, etc.).

I'll add some tests once we see whether or not there's more to be done with this.

Codecov Report

Base: 85.78% // Head: 79.31% // Decreases project coverage by -6.47% :warning:

Coverage data is based on head (ef2e465) compared to base (08bda43). Patch coverage: 39.24% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #18 +/- ## ========================================== - Coverage 85.78% 79.31% -6.48% ========================================== Files 8 8 Lines 401 464 +63 ========================================== + Hits 344 368 +24 - Misses 57 96 +39 ``` | [Impacted Files](https://codecov.io/gh/glue-viz/glue-plotly/pull/18?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=glue-viz) | Coverage Δ | | |---|---|---| | [glue\_plotly/html\_exporters/scatter3d.py](https://codecov.io/gh/glue-viz/glue-plotly/pull/18/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=glue-viz#diff-Z2x1ZV9wbG90bHkvaHRtbF9leHBvcnRlcnMvc2NhdHRlcjNkLnB5) | `58.78% <33.80%> (-17.89%)` | :arrow_down: | | [glue\_plotly/html\_exporters/tests/test\_scatter3d.py](https://codecov.io/gh/glue-viz/glue-plotly/pull/18/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=glue-viz#diff-Z2x1ZV9wbG90bHkvaHRtbF9leHBvcnRlcnMvdGVzdHMvdGVzdF9zY2F0dGVyM2QucHk=) | `97.67% <87.50%> (+0.30%)` | :arrow_up: | | [glue\_plotly/html\_exporters/scatter2d.py](https://codecov.io/gh/glue-viz/glue-plotly/pull/18/diff?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=glue-viz#diff-Z2x1ZV9wbG90bHkvaHRtbF9leHBvcnRlcnMvc2NhdHRlcjJkLnB5) | `82.52% <0.00%> (+0.97%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=glue-viz). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=glue-viz)

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glue-viz / glue-plotly

Add support for error bars, vectors, point size scaling to 3D scatter exporter. #18

Codecov Report