Allow the user to hide the ellipsoid drawn by EllipsoidJoint::generateDecorations()

[tkuchida]

Fixes Issue 1440 in GUI repo

Brief summary of changes

See discussion here.

Testing I've completed

Looking for feedback on...

How to test this without building the GUI from source…

CHANGELOG.md (choose one)

No need to update because minor change for small number of users.

---

This change is 

[tkuchida]

@aymanhab Are you able to test this in a GUI build, or perhaps there's a CI artifact that I can use without building the GUI from source? (Here's a test file: arm26_withEllipsoidJoint.txt) 🐇

[adamkewley]

Seems like a straightforward enough PR 👍

[aymanhab]

The changes look good @tkuchida Thanks for the fix. If you want an artifact of the GUI based on this branch you can create a PR that modifies the continuous-integration.yaml file to checkout the branch tkuchida-hideEllipsoidDecorations instead of main for opensim-core and then you can test the artifact from ci to see if they work as expected. I tried that here opensim-org/opensim-gui#1443 and would appreciate if you test when ci finishes.

[tkuchida]

@aymanhab Thanks for creating the artifact (direct link here, OpenSim-4.5-2023-05-04-ca13bf9-win64). I opened the test file (arm26_withEllipsoidJoint.txt) and toggled the "visible" flag under the EllipsoidJoint's "Appearance" property but the ellipsoid didn't disappear. I then tried manually adding the following to the .osim file:

<EllipsoidJoint name="myEllipsoidJoint">
    ...
    <Appearance>                  <!-- added -->
        <visible>false</visible>  <!-- added -->
    </Appearance>                 <!-- added -->
</EllipsoidJoint>

and no ellipsoid is drawn when the model is opened (here's the file: arm26_withEllipsoidJointHidden.txt). Not ideal but it will work for my student. I think this PR can be merged here but presumably the GUI needs to be patched as well. 🐶

[aymanhab]

Agreed, thanks @tkuchida

[tkuchida]

Thanks @aymanhab and @adamkewley