Moves meshes in the RayCaster to classvar to be shared between sensors

[pascal-roth]

Description

Moves meshes in the RayCaster to classvar to be shared between sensors. This should save memory.

Type of change

• Bug fix (non-breaking change which fixes an issue)

Checklist

• I have run the pre-commit checks with ./isaaclab.sh --format
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• I have updated the changelog and the corresponding version in the extension's config/extension.toml file
• I have added my name to the CONTRIBUTORS.md or my name already exists there

[Copilot]

Pull Request Overview

This PR moves the mesh storage for raycasting from instance attributes to class-level variables to allow sharing between sensors and reduce memory usage.

• Moves warp mesh and mesh view dictionaries to class-level with type annotations.
• Introduces an instance counter and a del method to clear the shared dictionaries when no instances remain.
• Updates the typing import to include ClassVar.

Comments suppressed due to low confidence (1)

source/isaaclab/isaaclab/sensors/ray_caster/ray_caster.py:314

• [nitpick] Relying on del for cleanup of shared class variables can be unpredictable due to Python's garbage collection behavior. Consider using an explicit cleanup method or context management to ensure reliable resource release.

def __del__(self):

[Mayankm96]

@pascal-roth Pre-commit is failing. Can you check?

[pascal-roth]

lets wait with a merge, just making some tests for the ray_caster to make sure that the new classvar is cleared correclty

[pascal-roth]

@Mayankm96 ready for a review, now the raycaster also has a first set of basic tests.

IMPORTANT: the test already run with pytest, commented out part at the top is for the time when everything is upgraded to pytest

[kellyguo11]

Looks like some tests are failing, is that expected?

[pascal-roth]

so regarding the tests:

• test_ray_caster.py: fail is expected as written in pytest (not sure why our unittest framework even catches that one)
• test_tiled_camera.py and test_contact_sensor.py fail but are not even in the log, don't think that is from this PR
• test_environment.py times out again

Lets really push for the pytest conversion, this will make the whole setup much easier