mujoco

<mujoco>
  <option>
    <flag sleep="enable"/>
  </option>

  <worldbody>
    <light pos="0 -1 4"/>
    <geom type="plane" size="1.5 1.5 .01" rgba=".5 .5 .5 .5"/>

    <body pos=".3 0 1" sleep="init">
      <freejoint/>
      <geom type="box" size=".1 .1 .1"/>
      <site name="1" pos="-.1 -.1 -.1" size=".01" rgba="1 0 0 1"/>
      <site name="2" pos=".1 -.1 -.1" size=".01" rgba="1 0 0 1"/>
    </body>

    <body pos="-.3 0 1" euler="10 20 30">
      <freejoint/>
      <geom type="box" size=".1 .1 .1"/>
      <site name="3" pos=".1 -.1 .1" size=".01" rgba="1 0 0 1"/>
    </body>

    <body pos=".7 0 1" sleep="init">
      <freejoint/>
      <geom type="box" size=".1 .1 .1"/>
      <site name="4" pos="-.1 -.1 -.1" size=".01" rgba="1 0 0 1"/>
    </body>
  </worldbody>

  <tendon>
    <spatial range="0 .6" width="0.01">
      <site site="1"/>
      <site site="3"/>
    </spatial>
    <spatial range="0 .6" width="0.01">
      <site site="2"/>
      <site site="4"/>
    </spatial>
  </tendon>
</mujoco>