It would always check both, so the bounds based collision would be
redundent. The collision code would see this as two seperate
arming collisions.
Doug Twilleager
Java 3D Team
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> Subject: Re: [JAVA3D] Optimising collision detection in J3D
> To: [EMAIL PROTECTED]
>
> If you set up a WakeupAnd condition with the first criterion a
> bounds-based collision detector and the second a geometry-based
> detector, would that always check both or stop checking if the bounds
> collision failed?
>
> -Jeremy Smoler
>
> Matthew Pocock wrote:
> >
> > I kind-of assumed that if you said USE_GEOMETRY that the collision engine
would
> > do an initial sweep using a realy stupid spherical bounds model, discard
every
> > pair that are clearly not colliding, and then perform the clever, accurate
> > geometry collision test. Am I wrong?
> >
> > "Leung, Sunny" wrote:
> >
> > > Hi Justin,
> > >
> > > Thanks for your response to my question in J3D interest group.
> > >
> > > I have tried the USE_BOUNDS method in the collision constructor instead of
> > > the USE_GEOMETRY parameter. Although the speed has increase significantly
> > > from the 8mins to 14sec., the accuracy of such method is unacceptable. Is
it
> > > possible to setup a CollisionBounds around an object using its shape3d
> > > information (vertices information).
> > >
> > > Instead of separating collidable and non-collidable objects in the
> > > scenegraph. Is it possible to instruct the collision detection node to
only
> > > perform collision detection within a certain radius (volume) around an
> > > object. For example, if there is no objects within a 2 meters radius of a
> > > particular object (Object A), the collision detection will not be
activated.
> > > If another object (Object B) is within the 2m radius of Object A, the
> > > collision detection node will activate and detect any possible collision
> > > between Object A and parts of Object B which are within the 2m radius of
> > > Object A.
> > >
> > > If the above approach is possible, it will greatly reduce CPU time (even
in
> > > USE_GEOMETRY mode) and at the same time maintain high level of accuracy.
> > >
> > > Please comments.
> > >
> > > cheers,
> > > Sunny Leung
> > >
> > > -----Original Message-----
> > > From: Justin Couch [mailto:[EMAIL PROTECTED]]
> > > Sent: Monday, July 26, 1999 1:14 PM
> > > To: [EMAIL PROTECTED]
> > > Subject: Re: [JAVA3D] Optimising collision detection in J3D
> > >
> > > Leung, Sunny wrote:
> > >
> > > > So is it possible to tell the collision detection node to detect
collision
> > > > only within a certain radius (volume) around the object which the node
is
> > > > attached onto?
> > >
> > > There are two things that you need to do. Firstly, for any objects that
> > > you _don't_ want to collide with, you turn collision detection off using
> > > setCollidable(false) defined in Node. The easiest way to do this is
> > > partition the scene graph into two groups - collidable and not
> > > collidable areas. Then, the parent group of all the not collidable stuff
> > > you setCollidable(false). This then works for all children of the group
> > > so that you don't need to explicitly set it.
> > >
> > > Next, you set the bounds for the objects you do want to collide with
> > > using the setCollisionBounds method of the parent group of the
> > > collidable object (defined in the Group class). If you want a spherical
> > > bounds for your object use BoundingSphere as the object that you set.
> > >
> > > Finally, when constructing your behaviour criterion, make sure you set
> > > it with the Node and the speed hint of USE_BOUNDS. I think you can also
> > > use the constructor that takes the Bounds reference and it automatically
> > > uses the USE_BOUNDS speed hint, but the docs aren't particularly clear
> > > on this.
> > >
> > > --
> > > Justin Couch Author, Java Hacker
> > > Snr Software Engineer [EMAIL PROTECTED]
> > > ADI Ltd, Systems Group http://www.vlc.com.au/~justin/
> > > Java3D FAQ: http://tintoy.ncsa.uiuc.edu/~srp/java3d/faq.html
> > > -------------------------------------------------------------------
> > > "Look through the lens, and the light breaks down into many lights.
> > > Turn it or move it, and a new set of arrangements appears... is it
> > > a single light or many lights, lights that one must know how to
> > > distinguish, recognise and appreciate? Is it one light with many
> > > frames or one frame for many lights?" -Subcomandante Marcos
> > > -------------------------------------------------------------------
> > >
> > >
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