faces
Controls the visual representation of a 
polytope Voronoi cluster.
When 
faces is 
yes (the default), the polyhedron is represented
by solid polygons, that users can see from the outside or from the inside.
When 
faces is 
no, the polyhedron is represented by wired
lines connecting the vertices.
Example: <group ... faces="yes"/> (default)
Allowed values: yes, no (optional)
atoms
In 
polytope Voronoi clusters, set the number of atoms to represent.
To disable this representation set 
atoms equal to 0.
Example: <cluster ... atoms="1"/> (no defaults)
Allowed values: 1 - INT_MAX (optional)
scale
Change the cluster size, including its child objects.The visual representation
of an object is always scaled by its own scale factor multiplied by the scale
factor of all its parent objects until layer, inclusive.
Polytope clusters are scaled around the cluster center, while
Container clusters are scaled around the viewport center. This happens
because 
Polytope clusters have a geometric center, defined by the
polyhedra, while 
Container clusters may have only atoms, and using its
geometric center as the scaling center has the weird effect that moving one
atom changes the visual representation of the other atoms, because the
scaling center and thus the scaling transformation has changed!
Example: <cluster ... scale="1.0"/> (default)
(defined in GAMGI_MESA_SCALE)
Allowed values: positive real (optional)