Hi Daniel
Send me the examples this yours "book implements collision detection"
about collision between the geometry and outher geometry of the virtual
scene.
Where I can find examples about it. I read only the example
"TickTockCollision" on /demo jdk 1.2.2.
I wait your mail.
[]s
Haroldo
>From: Daniel Selman <[EMAIL PROTECTED]>
>Reply-To: [EMAIL PROTECTED]
>To: [EMAIL PROTECTED]
>Subject: Re: [JAVA3D] Collision Detection - walking through walls.
>Date: Mon, 7 Feb 2000 01:53:41 -0000
>
>Anders,
>
>To use Java 3D collision detection you want to use a Behavior with a
>WakeupOnCollisionEntry / Exit condition. Create some geometry to represent
>the viewer (an avatar) and check for collisions between this geometry and
>the geometry in your scene.
>
>You either have to manually assign collision bounds
>(Group.setCollisionBounds - faster) or set the WakeupOnCollisionEntry
>object
>to use the USE_GEOMETRY mode.
>
>This should work but your problem will be that you will only detect a
>collision once it is too late, and if your framerate is low you will miss
>collisions. The current Java 3D implementation is not velocity based and is
>really "collision notification" (if you're lucky!).
>
>One of the longer examples in my book implements collision detection for a
>Doom style game. Essentially I cheat and within my key navigation behavior
>check whether the new position of the viewer would put them within one of
>the solid objects. I use an array to quickly look up the positions of solid
>objects. This works as the world is essentially 2D and in a simple maze
>environment the look up and transformation from world to "maze" coordinates
>is very fast and robust.
>
>An alternate (and maybe more general) scheme might be to use pick rays to
>check how far you are from the objects within your scene. You can do this
>within your navigation behavior and again allow or disallow the movement.
>This would be an "abuse" of picking though so performance might be an issue
>so write test code.
>
>It sounds like you are a little fuzzy about some general Java 3D topics.
>Perhaps a good place to start would be the tutorial, and then approach the
>collision detection.
>
>That's all I can think of!
>
>Sincerely,
>
>Daniel Selman
>
>[EMAIL PROTECTED]
>http://www.tornadolabs.com
>
> > -----Original Message-----
> > From: Anders Breivik [mailto:[EMAIL PROTECTED]]
> > Sent: 06 February 2000 20:35
> > To: [EMAIL PROTECTED]
> > Subject: Collision Detection - walking through walls.
> >
> >
> > Hello Daniel,
> >
> > Tanks for your reply to my previous question! The j3dtree application
>now
> > works fine together with my customised classes.
> >
> > I’m having some more problems though. This time its got to do
> > with collision
> > detection (!). I’ve tried the Java 3D – Interest mailing list,
> > but haven’t
> > received any response about this.
> >
> > I’m trying to implement a collision detection scheme where the
> > player of my
> > game does not walk through the walls when navigating around in different
> > rooms. I wish to detect when the view co-ordinates collides with
> > any object
> > in the scene. I find it difficult to do because it is hard to find any
> > detailed information about java3d’s collision detection schemes.
> > The sun’s
> > java3d web site is very useful, but I sometimes need more detailed
> > information.
> >
> > Anyway, I am writing to you (again) to see if you can give me some new
> > ideas. (I hope you don’t mind)
> >
> > My first idea was to use WakeupOnViewPlatformEntry/Exit(Bounds region)
>to
> > detect when the view co-ordinates collides with an object, and
> > then to alter
> > the key navigation accordingly. However, (as I understand it)
> > this requires
> > that the bounds region must fit/rap the collidable object as
> > accurately as
> > possible. I don’t know how to specify such a region for each
> > object in the
> > scene. Do you?
> > Besides, I think this scheme is not so good because specifying
> > such a region
> > for each object in the scene might be a big hassle.
> >
> > My other idea was to attach a small object very close to the view
> > co-ordinates and at run time update the co-ordinates of this object such
> > that it always is very close to the current view co-ordinates. I
> > could then
> > use WakeupOnCollisionEntry/Exit(Shape3D)
> > to detect if any other object collides with the “view object”. This view
> > object (the object close to the view co-ordinates) would be
> > positioned such
> > that the user never can see it. Is this a valid/better approach? I
>would
> > very much like to hear your opinion. (I haven’t managed to get
> > this working.
> > I can’t get the view object co-ordinates updated.)
> >
> >
> > I’m sure there are better ways to approach this problem, but I have not
> > figured them out. There must be someone who has implemented this
> > earlier and
> > I would like to learn how it is done. If you have any advise I would (as
> > usual) greatly appreciate your feedback.
> >
> >
> >
> > Sincerely
> > Anders Breivik
> >
> >
> > >From: "Daniel Selman" <[EMAIL PROTECTED]>
> > >Reply-To: <[EMAIL PROTECTED]>
> > >To: "Anders Breivik" <[EMAIL PROTECTED]>
> > >Subject: RE: j3dtree.jar
> > >Date: Thu, 3 Feb 2000 12:23:13 -0000
> > >
> > >Anders,
> > >
> > >You need to separate the names of the JAR files on the command
> > line with a
> > >semi-colon. E.g.
> > >
> > >javac -classpath j3dtree.jar;myother.jar *.java
> > >
> > >Check the API docs for javac for more options.
> > >
> > >Sincerely,
> > >
> > >Daniel
> > >
> > >[EMAIL PROTECTED]
> > >http://www.tornadolabs.com
> > >
> > > > -----Original Message-----
> > > > From: Anders Breivik [mailto:[EMAIL PROTECTED]]
> > > > Sent: 03 February 2000 13:14
> > > > To: [EMAIL PROTECTED]
> > > > Subject: j3dtree.jar
> > > >
> > > >
> > > > Hello Daniel,
> > > >
> > > > I'm having a small problem with the j3dtree program which is
> > > > integrated with
> > > > the rest of my code. Its all got to do with the classpath
> > > > settings: When I
> > > > compile with
> > > >
> > > > javac -classpath j3dtree.jar World.java
> > > >
> > > > it will not find my other customised java classes (UI.java for
> > > > instance)which are used within World.java. This is obviously
> > because the
> > > > classpath is altered. My question is: do you know what command line
> > > > arguments (MS-DOS)I should use in order to include both the
> > > > j3dtree.jar and
> > > > my additional java classes when compiling.
> > > >
> > > > Finally, thanks for your answers to all the questions I have
> > emailed you
> > > > earlied.
> > > >
> > > > Hope to hear from you again.
> > > >
> > > > Sincerely
> > > > Anders.
> > > >
> > > >
> > > > ______________________________________________________
> > > > Get Your Private, Free Email at http://www.hotmail.com
> > > >
> > > >
> > >
> > >
> >
> > ______________________________________________________
> > Get Your Private, Free Email at http://www.hotmail.com
> >
> >
>
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