<!-- 
  List all colision groups, used to group physics entities.
  Entities in the same group never collides.
  Value can be any positive integer > 0 (0 means no group, thus always collide).
 -->
<collisiongroups>
  <group name="toto" value="1"/>
  <group name="titi" value="2"/>
  <group name="tutu" value="2"/>
</collisiongroups>