mujoco

<mujoco model="collisions">
  <worldbody>
    <body name="box">
      <geom name="box" type="box" size="1 1 1"/>
    </body>
    <body pos="1.2 1.2 0.0">
      <!-- collides with box -->
      <joint/>
      <geom name="sphere_collides" type="sphere" size="1"/>
    </body>
    <body pos="-0.9 -0.9 0.0">
      <!-- collides with box, and is a predefined pair -->
      <joint/>
      <geom name="sphere_predefined" type="sphere"  size="0.1"/>
    </body>
    <body pos="1.8 -1.8 0.0" >
      <!-- doesn't collide with box, but requires narrowphase checking -->
      <joint/>
      <geom name="sphere_narrowphase" type="sphere" size="1"/>
    </body>
    <body pos="-2.1 -2.1 0.0">
      <!-- doesn't collide with box, and can be eliminated in broadphase -->
      <joint/>
      <geom name="sphere_broadphase" type="sphere" size="1"/>
    </body>
    <body name="sphere_excluded">
      <!-- collides with box, but is excluded -->
      <joint/>
      <geom name="sphere_excluded" type="sphere" pos="0.0 0.0 0.0" size="0.2"/>
    </body>
  </worldbody>
  <contact>
    <exclude body1="box" body2="sphere_excluded"/>
    <pair geom1="box" geom2="sphere_predefined"/>
  </contact>
</mujoco>