drawLine

send current position of defining points in scene to render object, and render line or line segment, in accordance with attribute setting

extend the drawing of the line to the given point if it is exterior to the segment connecting the line's point attributes

set position of line's lab, if any

Re-intialize list of traced lines to None

for consistency in iterating Element's rendering objects, all elements rendering information is in a list called self.rend. In the case of Lines, it is a single element list containing a cvisual curve object

export the scene's lines to PovRay SDL