Kelvin,
As requested, attached is a program to demonstrate the differences between
collisions in Java3d v1.1.x and v1.2 beta2.
under v1.2 beta2 the blue cube will pass through the red one.
under Java3d v1.1.x the blue cube will bounce off the red one.
This source code was generated by my program, so it is easy to generate
other cases. For example I can generate an example where v1.2 beta2 will
generate a collision even though the arming node is passing though empty
space.
If you want to setup other test cases, goto my site, load and run the
application, setup the simulation, then select export to java source from
the menu.
Martin
http://www.martinb.com/
----- Original Message -----
From: Kelvin Chung <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, April 28, 2000 7:14 PM
Subject: Re: [JAVA3D] Collision Behaviors
> Hi Martin,
> >
> >I've been using my program to do some experiments, this involves smashing
> >TransformGroups into each other, and seeing which ones generate
collisions,
> >here are the results:
> >
> >Test1 - arm and Target nodes are Shape3d
> >-------------------------------------------
> >This is the scene graph that I'm using:
> >
> >BranchGroup scene_branch
> >+-- TransformGroup blue_transform <-- transform3D changed every
frame
> >to move blue
> >| +-- Shape3d blue_shape <-- armNode for blue_behavior
> >| +-- Behavior blue_behavior
> >+-- TransformGroup red_transform <-- transform3D changed every frame
to
> >move red
> >| +-- Shape3d red_shape <-- armNode for red_behavior
> >| +-- Behavior red_behavior
> >
> >This works well in v1.2 and is a LOT faster than 1.1.x
> >
>
> For simple case Collision may slower because of the overhead
> in the internal data structure. But for large scene with lots
> of colliding object v1.2 should be faster.
>
>
> >Test2 - arm nodes are TransformGroups
> >----------------------------------------
> >This is the scene graph that I'm using:
> >
> >BranchGroup scene_branch
> >+-- TransformGroup blue_transform <-- used to move blue and as
armNode
> >for blue_behavior
> >| +-- Shape3d blue_shape
> >| +-- Behavior blue_behavior
> >+-- TransformGroup red_transform <-- used to move red and as armNode
> >for red_behavior
> >| +-- Shape3d red_shape
> >| +-- Behavior red_behavior
> >
> >In v 1.2 collision only occurs when the OTHER shape passes through
(0,0,0)
> >In v 1.1 it works as in test 1.
> >
> >I know there is an issue about the implicit conversion of bounds to
sphere
> >in transformGroups, but its not that, it is that the world coordinates of
a
> >TransformGroup are not affected by its own Transform.
> >
> >I was hoping to use the TransformGroups as the arm and Target nodes, but
it
> >looks like I'll have to use the Shape3D nodes?
> >
>
> This sounds like a bug in v1.2beta2, can you please send us the complete
> program to debug ?
>
> Thanks.
>
> - Kelvin
>
> ----------
> Java 3D Team
> Sun Microsystems
>
>
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mjbOutput.java
