HI Jeff ,Thank you very much for your help.
I cannot understand the collision in vizard although it looks very easy!

I have struggled to detect the collision event by more than one way but all them did not work

. I followed Farshizzo’s example on this link
http://forum.worldviz.com/showthread.php?p=5599
but did not work with my code
HTML Code:
def oncollide(e):
if e.obj1 in ball:
print 'colllision'
viz.callback(viz.COLLIDE_BEGIN_EVENT,oncollide)
May I ask here... how can I know who is e.obj1 1?
Any suggestion would be appreciated!