add support for mjGEOM_SDF

[nmarticorena]

Hi @kevinzakka, first thanks for all the effort on both mjviser and mjlab there are awesome tools to use.

This really small pr aims to add the capability to mjviser to use mjGEOM_SDF objects.

From the mujoco docs the SDF plugin for custom shapes in a mesh-free manner, by defining methods computing a signed distance field and its gradient at query points that is quite useful for non-convex geometries, due to the sdf plugin computes a visual mesh for rendering using marching cubes the only requirement for mjviser is treating mjGEOM_SDF as a mesh.

Currently when trying to load the xml example scene bowl.xm gets the current output:

Traceback (most recent call last):
  File "/home/vlu/Documents/extras/mjviser/.venv/bin/mjviser", line 10, in <module>
    sys.exit(main())
             ~~~~^^
  File "/home/vlu/Documents/extras/mjviser/src/mjviser/__main__.py", line 123, in main
    Viewer(model, data, server=server).run()
    ~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/vlu/Documents/extras/mjviser/src/mjviser/viewer.py", line 76, in __init__
    self.scene = ViserMujocoScene(self._server, model, num_envs=num_envs)
                 ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/vlu/Documents/extras/mjviser/src/mjviser/scene.py", line 200, in __init__
    self._add_fixed_geometry()
    ~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/vlu/Documents/extras/mjviser/src/mjviser/scene.py", line 1104, in _add_fixed_geometry
    merge_geoms(self.mj_model, sub_geom_ids),
    ~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/vlu/Documents/extras/mjviser/src/mjviser/conversions.py", line 588, in merge_geoms
    meshes.append(create_primitive_mesh(mj_model, geom_id))
                  ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
  File "/home/vlu/Documents/extras/mjviser/src/mjviser/conversions.py", line 307, in create_primitive_mesh
    mesh = _create_shape_mesh(geom_type, mj_model.geom_size[geom_id])
  File "/home/vlu/Documents/extras/mjviser/src/mjviser/conversions.py", line 281, in _create_shape_mesh
    raise ValueError(f"Unsupported shape type: {geom_type}")
ValueError: Unsupported shape type: 8

After this small change the behavior is as expected

[kevinzakka]

Thank you for the contribution @nmarticorena!

[kevinzakka]

Could you just fix the lint formatting test?

[nmarticorena]

Thanks for the quick response!, changes applied