[quote author=Fu-Kwun Hwang link=topic=2009.msg8574#msg8574 date=1316513514]
In the above simulation, the object is leaving when it is on the horizontal track.
It is always starts from stage==0, then move to stage==1, 2,3
Those are different stages in one complete trip.

What do you mean by "start on a straight horizontal track"?
Do you mean moving in from the right side (with velocity pointing to the left)?

I mean move to the right v = + and start on the left side x=xmin+size2

I created an addon stage ==4 I was trying to remix into an additional option for exploring straight line
For which it if selected go stage 4,1,2 or 3
Everything is the same as your simulation in stage 0,1,2or3