World files cannot load models via URI (to fuel.ignitionrobotics.org)

[wolfgangschwab]

Using a world file that contains URIs to fuel.ignitionrobotics.org generates errors.

I added some code to my local copy of the repository to solve this issue. So, models are automatically loaded from the website. If you are interested in the solution, I can generate a Pull request with this.

[traversaro]

Hi @wolfgangschwab,
thanks a lot for opening the issue. @diegoferigo can confirm this, but I guess that fuel URIs should be supported, so I think we are indeed interested in fixing this issue, so feel free to provide the details of your solution. Furthermore, I guess it would be useful to know which version of gym-ignition you are using, and if you have a self-contained example that reproduces the issue it would be great too.

[diegoferigo]

With the released versions of gym-ignition I never tried to load world with models included as Fuel URIs, I would not be surprised if something would not work. However, thinking about how the world model is processed, it should be ignition::gazebo::Server responsibility to download resources from fuel. @wolfgangschwab If you already found a missing piece from our side, I'd be happy to check it.

Spoiler alert: If you didn't notice, we're in the process of a big C++ refactoring #155, and in the refactoring branch I added the possibility to download Fuel models as function calls directly from C++ and Python:

gym-ignition/cpp/scenario/gazebo/include/scenario/gazebo/utils.h

Lines 48 to 49 in a303413

	std::string getModelFileFromFuel(const std::string& URI,
	const bool useCache = false);

Fuel support is one of many new features that are coming soon. The refactoring branch is not yet usable, but I think it could hit the nightly channel in few weeks.

[wolfgangschwab]

The major point was, that callback-functions were missing in GazeboWrapper::findAndLoadSdf . So I added

    sdf::setFindCallback(myFetchResource);
    ignition::common::addFindFileURICallback(myFetchResourceUri);

Additionally I had to write the callback-functions and add the ignition fuel-tools package. For world files this works. With robots I still have problems. But currently I'm looking more how laser-sensors (Lidar) can be used. As I understand currently Laser sensors are not implemented. Do you have plans to do so in the near future?

[diegoferigo]

@wolfgangschwab thanks a lot for the suggestion, I'll have a look!

But currently I'm looking more how laser-sensors (Lidar) can be used. As I understand currently Laser sensors are not implemented. Do you have plans to do so in the near future?

I general, sensors are not yet supported by the framework. In the next months we have other features we need with more urgency, I doubt anyone would start looking into sensors integration in the next few months. If you're interested in contributing, I'd be happy to discuss in a new issue how to implement them.

[wolfgangschwab]

Thanks, I will open a new issue for the Lidar-Sensors.

Regarding the fix for using URI with fuel: Just tell me, if you would like to get additional info or a Pull request.

[diegoferigo]

Regarding the fix for using URI with fuel: Just tell me, if you would like to get additional info or a Pull request.

Go ahead with a PR, you can target directly master for this fix. In the meantime, I check if I have to do the same also in the new architecture of the refactoring branch. Thanks a lot!

Thanks, I will open a new issue for the Lidar-Sensors.

Perfect, thanks!

[wolfgangschwab]

I raised Pull Request #174 to solve this issue.

[diegoferigo]

Closed via #309