Collision detection is a subset of a host of problems that show up in
combined discrete-continuous simulation. It's hard (maybe impossible) to do
hi-fi combined simulations in real time, but you can avoid rolling back a
segment of a simulation after you've put the result into phosphor by
slipping the display by a small phase delay - in some simple cases, it can
be just a single frame - so that you can compute a new state on speculation,
save it, then at the next clock tick, you can check whether any discrete
events happened in the interim before you post those results. If one did
happen, you have to scrap your speculative solution and deal with that
event.
A couple of years ago, I wrote a widely ignored paper on it for the Winter
Simulation Conference from the process simulation angle.
http://www.brockeng.com/wsc96/wsc96doc.htm
Cheers,
Fred Klingener
Brock Engineering
----- Original Message -----
From: "Yazel, David J." <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, November 16, 2000 11:14 AM
Subject: Re: [JAVA3D] Collision Detection!
> The problem people generally want to solve is not really collision
> detection, but collision prediction and collision avoidance. Before you
move
> your object, you need to check to see if the new location will result in
> there being a collision, if so then you do NOT actually make the move.
> Since java 3d reports after there has been a collision, it is generally
too
> late to stop the objects from merging. There are two solutions people
seem
> to do. one is to sort all your polygons in to a 3d tree of some kind,
like
> an oct-tree, use this to find objects which are in close proximity to your
> moving object, then do more detailed checking. The other is to send out
> pickrays in the direction your object is moving to find objects to check
> against. To do the actual check you can check all the polygons, or using
> bounding volumns to check for intersections.
>
> Dave Yazel
> Cosm Development Team
>
> > ----------
> > From: Tina Manoharan Valappil[SMTP:[EMAIL PROTECTED]]
> > Reply To: Discussion list for Java 3D API
> > Sent: Thursday, November 16, 2000 10:39 AM
> > To: [EMAIL PROTECTED]
> > Subject: [JAVA3D] Collision Detection!
> >
> > Hello,
> >
> > I saw the collision detection program under the demos for java3D. But
what
> > the program does is, it changes the color of the object that collides
with
> > another object in the scenegraph. But, what if I want to stop the object
> > from passing through the other object. Can somebody help me please.
Maybe
> > an example program would be really nice.
> >
> > Thanks in advance
> > tina
> >
> > Tina Manoharan
> > PhD. Heriot Watt University
> > Ph: 07801 069485 (mobile)
> > Ph: 0131 449 5111 ext. 4191 (office)
> > Ph: 0131 449 5111 ext. 4197 (lab)
===========================================================================
To unsubscribe, send email to [EMAIL PROTECTED] and include in the body
of the message "signoff JAVA3D-INTEREST". For general help, send email to
[EMAIL PROTECTED] and include in the body of the message "help".
