Class Lines

      object --+    
               |    
common.Primitive --+
                   |
                  Lines

Class to draw a set of lines in OpenGL.  Will be drawn
in the current OpenGL drawable.  This includes the ability
to draw into Maestro's Workspace.  It just needs to be
the current drawable.

Lines with the same characteristics must be placed
(color, width) into a single Lines instance.

See doc string for __init__ for details on instantiation.

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

line_grp = common.Group()
st = maestro.workspace_get()
color='red'
displacement = 1.0
for at in st.atom: 
    vert = [
        (at.x - displacement, at.y, at.z),
        (at.x + displacement, at.y, at.z),
        (at.x, at.y - displacement, at.z),
        (at.x, at.y + displacement, at.z),
        (at.x, at.y, at.z - displacement),
        (at.x, at.y, at.z + displacement),
    ]
    # Add the primatives to the container.
    line_grp.add(lines.Lines(vertices=vert, color=color))

# Add the draw callback.
maestro.workspace_draw_function_add(line_grp.draw)

# Hide the markers.
line_grp.hide()

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

Lines constructor requires:

vertices: List of vertex coordinates (x, y, z).
          Each vertex coordinate is itself an xyz list:
          [[x1,y1,z1],[x2,y2,z2]...]
          Treats each pair of vertices as an independent
          line segment.  Total number of vertices should be 2n.
          N/2 lines are drawn.  It is an error to
          specify an odd number of vertices.

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:

width (float):  Defaults to 1.0.  Lines are always drawn out
                anti-aliased.  So the actual width is determined
                at rasterization time.  Not all widths are
                supported and if an unsupported width is chosen,
                the nearest supported with is used.  Only width
                1 is guaranteed to be supported.