Use mouse controls to rotate the drawing. Use the key 'D' to draw. Use the key 'G' to grab and drag points along the line. Use the key 'C' to clear/erase all of the artwork. The variable 'speed' is how fast you can rotate the drawing with the mouse and the variable 'drawing_plane' is how close to the camera you are drawing.
Update: I have just made it easier to grab and drag a point
