Class MaestroArrow

      object --+        
               |        
common.Primitive --+    
                   |    
           ArrowCore --+
                       |
                      MaestroArrow

Class for creating a 3D arrow in Maestro

See doc string for __init__ for details on instantiation

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

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

arrow_grp = common.Group()
st = maestro.workspace_get()
for bond in st.bond:
    ar = arrow.MaestroArrow(
        xhead=bond.atom2.x, yhead=bond.atom2.y, zhead=bond.atom2.z,
        xtail=bond.atom1.x, ytail=bond.atom1.y, ztail=bond.atom1.z,
        color='red',
        radius=0.15,
        opacity=0.8,
        resolution=50
    )
    # Add the primative to the container.
    arrow_grp.add(ar)

# Unlike Arrow MaestroArrow simply needs to be shown to be drawn.
# No special callback like there is for Arrows is needed.
arrow_grp.show()

# Hide the markers.
arrow_grp.hide()

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

Constructor requires:

xhead, yhead, zhead: corrdinate of the head position
xtail, ytail, ztail: coordinate of the tail position

color:    One of:
            Color object (Color class)
            Color name (string)
            Tuple of (R, G, B) (each a float in range 0.0-1.0)

Optional arguments:

radius:   radius of the arrow in Angstroms
          Default: .15
opacity:  0.0 (invisible) through 1.0 (opaque)
               Default: 0.0
resolution:    Ranges from ?? to ??.  Default: ??