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>

  <option gravity="0 0 -9.81" sdf_iterations="3" sdf_initpoints="10"/>
  <asset>
    <mesh name="torus">
      <plugin instance="torus"/>
    </mesh>
    <mesh name="die" file="asset/die.obj" scale="1 1 1"/>
  </asset>

  <include file="scene.xml"/>

  <worldbody>
    <body pos="0 .05 2.5" euler="90 0 0">
      <freejoint/>
      <geom type="sdf" mesh="torus" rgba=".8 .17 .15 1" group="1">
        <plugin instance="torus"/>
      </geom>
    </body>
    <body>
      <geom type="mesh" mesh="die" euler="90 0 0" rgba="0 0 1 .2"/>
    </body>
    <light pos="1 0 7" dir="0 0 -1" castshadow="false"/>
    <light pos="-1 0 7" dir="0 0 -1" castshadow="false"/>
  </worldbody>
</mujoco>