how to draw 2D figure , for example a circle, in the screen, no the in 3D screen

[Jeff]

Here's a simple example that draws a circle to the ortho layer:

import viz
import vizshape

viz.go()

circle = vizshape.addCircle(parent=viz.ORTHO)
circle.setScale([100,100,1])
circle.disable(viz.LIGHTING)

viz.link(viz.CenterCenter,circle)