mujoco

<mujoco>
  <extension>
    <plugin plugin="mujoco.sdf.torus">
      <instance name="torus">
        <config key="radius1" value="0.35"/>
        <config key="radius2" value="0.15"/>
      </instance>
    </plugin>
  </extension>

  <asset>
    <mesh name="torus">
      <plugin instance="torus"/>
    </mesh>
  </asset>

  <option sdf_iterations="10" sdf_initpoints="40"/>

  <include file="scene.xml"/>

  <default>
    <geom solref="0.01 1" solimp=".95 .99 .0001" friction="0.1"/>
  </default>

  <worldbody>
    <body pos="-1 0 3.8">
      <freejoint/>
      <geom type="sdf" mesh="torus" rgba=".2 .2 .8 1">
        <plugin instance="torus"/>
      </geom>
    </body>
    <body pos="-1 0 3.4">
      <freejoint/>
      <geom type="sdf" mesh="torus" rgba=".2 .8 .2 1">
        <plugin instance="torus"/>
      </geom>
    </body>
    <body pos="-1 0 3">
      <freejoint/>
      <geom type="sdf" mesh="torus" rgba=".8 .2 .2 1">
        <plugin instance="torus"/>
      </geom>
    </body>
    <body pos="0 0 2">
      <geom type="cylinder" size=".1" fromto="1 0 -1 -1 0 1"/>
    </body>
    <body pos="0 0 2">
      <geom type="cylinder" size=".5" fromto="1.2 0 -1.2 1 0 -1"/>
    </body>
    <light name="left" pos="-2 0 7" cutoff="80"/>
    <light name="right" pos="2 0 7" cutoff="80"/>
  </worldbody>
</mujoco>