Class MaestroSphere

      object --+        
               |        
common.Primitive --+    
                   |    
          SphereCore --+
                       |
                      MaestroSphere

Class to create a 3D sphere in Maestro.  This sphere will be drawn
at the appropriate time in Maestro to interact properly with transparent
objects.

See doc string for __init__ for details on instantiation.

Spheres should be added to a Group and drawing done via the Group.
See Group documentation.

API Example
-----------
import schrodinger.maestro.maestro as maestro
import schrodinger.graphics3d.common as common
import schrodinger.graphics3d.sphere as sphere

sphere_grp = common.Group()
st = maestro.workspace_get()
for at in st.atom:
    sph = sphere.MaestroSphere(
        x=at.x,
        y=at.y,
        z=at.z,
        radius=1.0,
        resolution=20,
        opacity=0.8,
        color='red'
    )
    # Add the primative to the container.
    sphere_grp.add(sph)

# Unlike Sphere MaestroSphere simply needs to be shown to be drawn.
# No special callback like there is for Spheres is needed.
sphere_grp.show()


# Hide the markers.
sphere_grp.hide()

# Remove the markers and the callback.
sphere_grp.clear()
maestro.workspace_draw_function_remove(sphere_grp.draw)

Constructor requires:

x, y, z:  coordinate specifying center of sphere in Angstroms.

color:    One of:
            Color object
            Color name (string)
            Tuble of (R, G, B) (each 0.0-1.0)

radius:   radius of the sphere in Angstroms


Optional arguments:

opacity:  0.0 (transparent) through 1.0 (opaque)
               Defaults to 1.0
resolution:    4 to 50
               Defaults to 16