mujoco

<mujoco>
  <asset>
    <mesh name="incomplete_convex" inertia="convex"
          vertex="0 0 0  1 0 0  0 1 0  0 0 1"
          face="2 0 3  0 1 3  1 2 3" />
    <mesh name="complete"
          vertex="0 0 0  1 0 0  0 1 0  0 0 1"
          face="2 0 3  0 1 3  1 2 3  1 0 2"/>
  </asset>
  <worldbody>
    <body>
      <geom type="mesh" mesh="incomplete_convex"/>
    </body>
    <body>
      <geom type="mesh" mesh="complete"/>
    </body>
  </worldbody>
</mujoco>