Also builds realsense-viewer

[svddries]

After installing librealsense with Conda we found that some of the utility tools, such as realsense-viewer are not included. That makes perfect sense, because those tools are optional (they are even behind a BUILD_GRAPHICAL_EXAMPLES CMake option) and pull in a lot more dependencies. When librealsense is installed through apt using Intel's PPA, you have to install a separate package to get those tools (librealsense2-utils).

This is just a Draft PR showing how the viewer can be build, but as you can see it's certainly not optimal and pulls in quite a lot of extra dependencies. What do you think is the best way to tackle this? As I see it, I could:

1. Simply clean up this PR (I still need to verify if realsense-viewer actually works with the real hardware), but it means that with librealsense, users will also pull in a lot of extra dependencies
2. Create a separate feedstock for just the viewer / tools, but I'm not sure how we could manage the compatibility with this feedstock (e.g. rebuilding the librealsense 'core' library, vs. depending on it somehow)
3. Use multiple outputs for this feedstock (which I believe conda build can do, but we would need a bit of help...)

Looking forward to your view on this!

Checklist

• Used a personal fork of the feedstock to propose changes
• Bumped the build number (if the version is unchanged)
• Reset the build number to 0 (if the version changed)
• Re-rendered with the latest conda-smithy (Use the phrase @conda-forge-admin, please rerender in a comment in this PR for automated rerendering)
• Ensured the license file is being packaged.

[conda-forge-linter]

Hi! This is the friendly automated conda-forge-linting service.

I just wanted to let you know that I linted all conda-recipes in your PR (recipe) and found it was in an excellent condition.

[traversaro]

Hi @svddries ! I am totally fine with starting with 1. and then doing 3. when we actually have the need to do so. Multiple outputs conda recipes are indeed something that I still do not master completly, if you want an example of a multiple output recipe, see:

• https://github.com/conda-forge/libode-feedstock/blob/212d34e7cd0cbb52c680c787eef36adb16690b52/recipe/meta.yaml
• List of other recipes including multi-output, I did not checked them Add link to 'well-done' packages conda-forge.github.io#1483

Just an additional datapoint, note that this package is also being packaged at the robostack level at the moment, see ros-noetic-librealsense2 and ros-galactic-librealsense2 in https://robostack.github.io/noetic.html and https://robostack.github.io/galactic.html . If you install both, you could get incompatibilities. See RoboStack/robostack.github.io#17 for a more general instance of the problem that eventually we would like to tackly systematically, but that I guess no one is planning to work in in the short term.

[svddries]

Hi @traversaro, thanks for your reply (and sorry for my delayed response)! The multi-output recipe actually doesn't look that difficult, so I think I'll try to rewrite this PR to use that (after I've successfully tested the viewer with actual hardware). Will be a nice exercise :).

To be completely transparent: getting the realsense tooling to work is not a direct necessity for us now, but will be somewhere in the next couple of weeks. This means that it may take some time before I get to it, but I'll definitely pursue it somewhere in the next month or so!

Also, thanks for the heads-up about ros-(noetic|galactic)-librealsense2. The general issue is interesting as well - maybe something we can help with in the near future!

[traversaro]

@svddries I guess this has stalled, I opened #49 to track this improvement, in the meanwhile I guess we can close this PR, if anyone wants to work on this feel free to open a new one.