Support `<gazebo_ros>` in `package.xml` exports

[azeey]

🎉 New feature

Summary

This copies the implementation from gazebo_ros_paths.py to provide a way for packages to set resource paths from package.xml.

e.g.  <export>
          <gazebo_ros gazebo_model_path="${prefix}/models"/>
          <gazebo_ros gazebo_media_path="${prefix}/models"/>
      </export>

The value of gazebo_model_path and gazebo_media_path is appended to GZ_SIM_RESOURCE_PATH The value of plugin_path appended to GZ_SIM_SYSTEM_PLUGIN_PATH.

This will make transition from Gazebo Classic easier.

Test it

Checklist

• [ ] Signed all commits for DCO
• [ ] Added tests
• [ ] Added example and/or tutorial
• [ ] Updated documentation (as needed)
• [ ] Updated migration guide (as needed)
• [ ] Consider updating Python bindings (if the library has them)
• [ ] codecheck passed (See contributing)
• [ ] All tests passed (See test coverage)
• [ ] While waiting for a review on your PR, please help review another open pull request to support the maintainers

Note to maintainers: Remember to use Squash-Merge and edit the commit message to match the pull request summary while retaining Signed-off-by messages.

[azeey]

it might be worth it to add a tutorial about this or small doc about this.

Good point!

Do you have plans to forward port this to Iron and Rolling?

Yes, I'll cherry-pick this to Iron and Rolling. I was going to start on Rolling first, but I wanted to make sure the humble branch got the IGN_* variables modified as well.

[DLu]

Are we waiting on the Tutorial to get this merged?

I have a URDF/Gazebo tutorial waiting to be merged and there is a section ("Side note: Configuring meshes") that covers this area. The tutorial is written for for Gazebo Classique, but as linked above, I'm trying to get the Gazebo New Coke version to work too.

[azeey]

@ahcorde , @DLu I've added a section to the README that explains how to use this. Let me know your thoughts. This could be expanded into a full tutorial on gazebosim.org/docs.

[DLu]

[ahcorde]

@azeey do you have any plan to forward port this to iron and rolling?

[rakeshv24]

@azeey is this feature included in the jazzy release yet?

[azeey]

Ah, this fell through the cracks. I've started the forward port process: https://github.com/gazebosim/ros_gz/pull/564

[rakeshv24]

Thanks!