Simulate a basketball

[drAshcroft]

Hello all, I have been working on a simple RL system where an arm bounces a ball. The problem seems to be that the ball does not bounce.

` backend_name = os.environ.get(BACKEND_ENV, "cpu")
genesis.init(backend=getattr(genesis, backend_name), logging_level="warning")

scene = genesis.Scene(
    sim_options=genesis.options.SimOptions(dt=DT, substeps=SUBSTEPS),
    show_viewer=False,
)
scene.add_entity(
    genesis.morphs.Plane(),
    material=genesis.materials.Rigid(
        friction=0.5,
        coup_restitution=spec.restitution,
        **RIGID_MATERIAL_KWARGS,
    ),
    name="demo_restitution_plane",
)
ball = scene.add_entity(
    genesis.morphs.Sphere(
        pos=(0.0, 0.0, DROP_HEIGHT_M),
        radius=spec.radius,
        fixed=False,
    ),
    material=genesis.materials.Rigid(
        rho=_sphere_density(spec),
        friction=0.5,
        coup_restitution=spec.restitution,
        **RIGID_MATERIAL_KWARGS,
    ),
    name="demo_restitution_ball",
)
scene.build()

`

Is there another way to get the ball to bounce and act like an elastic object?