September 2009


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MASON Multiagent Simulation Toolkit <[log in to unmask]>
Fri, 4 Sep 2009 09:49:53 +0200
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Sean Luke <[log in to unmask]>
To: MASON Multiagent Simulation Toolkit <[log in to unmask]>
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We mostly picked Java3D because early on there weren't many good 
options, particularly on the Mac.  Jumping to another scene-graph 
library is plausible but I'm not sure if it's worth the intellectual 
investment at this stage.  Perhaps later on when other libraries really 
start to gain some major traction.  [Java3D is moving very slowly of 
course.  But it's moving!]

BTW, some but not all of the statements I made below are, I think, 
false.  I've cleaned things up a lot in the revised commit I just made 
and I think people will be happy.


Miles Parker wrote:
> Sean, have you ever looked into LWJGL?  That's what the Eclipse GEF3D 
> folks are using and through that also the (fairly rudimentary) 3D 
> support AMP provides. Though LWJGL doesn't have the most sensible 
> interface in the world either -- at least it isn't low-level 
> masquerading as high-level, and the performance seems quite good.
> On Sep 2, 2009, at 7:21 AM, Sean Luke wrote:
>> Okay, here's the deal.
>> Java3D isn't, shall we say, the easiest to use rendering system.  But 
>> it's what we need to make do with.  :-(  One of the problems with 
>> Java3D is that it has a lot of hidden, undocumented nonsense. 
>>  Changing colors in spheres is one of them.  Things that Sun never 
>> told us:
>> 1. You can't create a *new* Appearance object once the scene is live 
>> -- you have to change the existing one.
>> 2. BUT you still have to call setAppearance(...) with this existing 
>> object.
>> 3. AND you have to call setAppearance on the shape, not the 
>> SpherePortrayal3D.  Even though the SpherePortrayal3D has... as 
>> setAppearance method.
>> Grrr...
>> Okay, I've got something working, so if you need something immediately 
>> I can provide you with an example, and two revised files, which will 
>> change colors as you like.  But to do it well and properly, I'll need 
>> to make a few more tweaks.
>> Sean
>> On Sep 2, 2009, at 6:59 AM, Joerg Hoehne wrote:
>>> Dear developers,
>>> I'm trying to change the color of an SpherePortrayal3D object during 
>>> runtime. I've checked my
>>> code and I'm positive the color of the object will be changed but not 
>>> visualized accordingly.
>>> I've got the impression the color of a XXXPortrayal3D object can't be 
>>> changed after the first
>>> construction (or display) of the 3D scene by j3d. Before the first 
>>> construction/display I was able to
>>> change the color with the same code snipped found below.
>>> Here is the code snippet anyway ('this' references to a subclassed 
>>> SpherePortrayal3D object):
>>> this.appearance = SpherePortrayal3D.appearanceForColor(color);
>>> There has been a discussion some years ago about a similar topic 
>>> (changing the transparency
>>> during runtime) and I wonder if a solution has been found.
>>> I'm working on a Mac with OS X 10.6. The monitored effect might be os 
>>> depended because j3d
>>> might cache some information about the displayed objects and assumes 
>>> some properties won't
>>> change in the future.
>>> Help!
>>> Jörg
>>     skype:  milestparker
>>     vox: 509-643-4441
>>     mailto:[log in to unmask]
>> <>