Allow passing additional search paths by setting an environment variable

[flferretti]

There are cases in which the Python package is used quite extensively and there multiple calls to resolve some mesh URIs, e.g. https://github.com/ami-iit/jaxsim/blob/main/src/jaxsim/mujoco/loaders.py. This pull requests adds the possibility to set an environment variable in order to add custom search paths globally and it updates the README accordingly.

Examples

• Not passing additional search paths

% resolve-robotics-uri-py package://example-robot-data/robots/ur_description/meshes/ur10/collision/shoulder.stl

resolve-robotics-uri-py: No file corresponding to URI 'package://example-robot-data/robots/ur_description/meshes/ur10/collision/shoulder.stl' found

• Using env var with single path

% RRU_ADDITIONAL_PATHS=~/.cache/robot_descriptions resolve-robotics-uri-py package://example-robot-data/robots/ur_description/meshes/ur10/collision/shoulder.stl

/home/fferretti/.cache/robot_descriptions/example-robot-data/robots/ur_description/meshes/ur10/collision/shoulder.stl

• Using env var with multiple paths

% RRU_ADDITIONAL_PATHS=~/.cache/robot_descriptions:~/.cache/robot_descriptions/example_model_data resolve-robotics-uri-py package://example-robot-data/robots/ur_description/meshes/ur10/collision/shoulder.stl

/home/fferretti/.cache/robot_descriptions/example-robot-data/robots/ur_description/meshes/ur10/collision/shoulder.stl

• Using argument with multiple paths

% resolve-robotics-uri-py --package_dirs ~/.cache/robot_descriptions:~/.cache/robot_descriptions/example-robot-data package://example-robot-data/robots/ur_description/meshes/ur10/collision/shoulder.stl

/home/fferretti/.cache/robot_descriptions/example-robot-data/robots/ur_description/meshes/ur10/collision/shoulder.stl

Documentation Improvements:

• Updated the installation instructions in README.md to replace mamba with conda for consistency and simplicity. (README.md, README.mdL12-R12)
• Added a new section in README.md explaining how to specify custom search paths for the resolve-robotics-uri-py tool, including examples for both command-line usage and Python code. (README.md, README.mdL48-R82)

Code Enhancements:

• Enhanced the resolve_robotics_uri function to support additional search paths specified via the RRU_ADDITIONAL_PATHS environment variable. This allows users to define custom directories for resolving URIs, improving flexibility. (src/resolve_robotics_uri_py/resolve_robotics_uri_py.py, src/resolve_robotics_uri_py/resolve_robotics_uri_py.pyR106-R111)

[traversaro]

Just to understand, why we need yet another env variable instead of reusing of the existing env variables?

[flferretti]

Just to understand, why we need yet another env variable instead of reusing of the existing env variables?

I thought it would be better to avoid using env variables from Gazebo/ROS to keep the module-specific paths separated and avoid interference

[traversaro]

Ack, thanks! Can you clarify this is in the docs? Because as it is written, it seems that if you have a custom directory you can't just add it to existing env variables, that would have the benefit to work with any other software that consumes URDFs. Furthermore, there is any reason why we can't just add RRU_ADDITIONAL_PATHS to SupportedEnvVars structure instead of adding a new code path?

[flferretti]

Ack, thanks! Can you clarify this is in the docs? Because as it is written, it seems that if you have a custom directory you can't just add it to existing env variables, that would have the benefit to work with any other software that consumes URDFs. Furthermore, there is any reason why we can't just add RRU_ADDITIONAL_PATHS to SupportedEnvVars structure instead of adding a new code path?

You're right! Done in eee7a40, 63b9d7d and 74981ea