If you just want to display grid lines overlayed on the screen, then you can use the vizshape.addGrid command. Here is an example:
Code:
import viz
import vizshape
viz.go()
grid = vizshape.addGrid([1,1],step=0.1,boldStep=None,axis=vizshape.AXIS_Z,parent=viz.SCREEN)
grid.color(viz.RED)
grid.setPosition([0.5,0.5,0])
You can adjust the
step argument to control the distance between the lines.