Write using phantom omni

[Jeff]

The 'write' function is probably called continuously as long as button1 is held down. If that's the case the final value of pos0 will be the same as pos1. You could add a flag so that the write function only saves to pos0 the first time it is called. Then reset the flag when the buttonup event occurs.

[M@rcello]

Hy jeff and thanks to give always an answer to my doubts.
The function write is called every time that button 1 is pressed,it doesn't matter if it held down or not.
Anyway,I have found on this forum a similar post,in which you suggested to use the pencil from the tools module.
This is the code and it works:

import viz
import vizact
import vizshape
import vizact
import vizmat
import viztask

viz.go()

viz.MainView.setPosition(0,0,-40)
viz.clearcolor(viz.GRAY)

sensable=viz.add('sensable3.dle')
device=sensable.addHapticDevice()
device.workspace.setScale([10,10,10])

from tools import pencil
tool=pencil.Pencil()

pen=viz.add('art/pencil.obj')
pen.setPosition([0,0,-2])
pen.setScale([0.05,0.05,0.05])

cube=viz.add('art/box.wrl')
cube.color(0,0,0)
cube.setScale([35,20,0.1])

cube1=viz.add('art/box.wrl')
cube1.setPosition([-17.5,0,0])
cube1.setScale([1,21,0.2])
cube1.color(0,255,0)

cube2=viz.add('art/box.wrl')
cube2.color(0,255,0)
cube2.setPosition([17.5,0,0])
cube2.setScale([1,21,0.2])

cube3=viz.add('art/box.wrl')
cube3.color(0,255,0)
cube3.setPosition([0,10,0])
cube3.setScale([35,1,0.2])

cube4=viz.add('art/box.wrl')
cube4.color(0,255,0)
cube4.setPosition([0,-10,0])
cube4.setScale([35,1,0.2])

myButton = viz.addButtonLabel('Erase')
myButton.setPosition(0.5,0.1,0)
myButton.setScale(3,1,1)

count=0

def MyTask():
	while True:
		yield viztask.waitButtonDown(myButton)
		tool.clear()
viztask.schedule( MyTask())

def UpdateModel():
	line = viz.MainWindow.screenToWorld(device.getPosition())
	pen.setPosition(line.endFromDistance(40))	
vizact.ontimer(0,UpdateModel)

def write(e):
	if e.button==0:
		update(tool)
		viz.link(pen,tool)
viz.callback(viz.SENSOR_DOWN_EVENT,write)

def update(tool):
	tool.draw()
tool.setUpdateFunction(update)

The problem is that when i press the button of the stylus it starts drawing the trajectory but it never ends. I am looking to implement some control so that when the button is pressed again the trajectory is not drawn, and again if i press the button for the third time the system starts again drawing the trajecotry.I hope it is clear
Suggestions?
I need something like when you enter in this function,execute and repeat it until this event happens. The problem is that with the while loop everything freeze