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Subject: 
Re: JAVA - Viewer for dat-Files
Newsgroups: 
lugnet.cad, lugnet.cad.dat.parts
Date: 
Sat, 26 Jan 2002 12:43:21 GMT
Viewed: 
330 times
  
"Kyle McDonald" <kmcdonald@bigfoot.com> schrieb im Newsbeitrag news:3C519D02.2040901@bigfoot.com...
Hi,
for how I'm doing the internal creating:

I did a depth search with hashing the files, create two shapes for
all lines, quads, triangles, each partitioned in solid and transparent.
So I got finally one Branchgroup with six shapes and two appearances.

most games.  They generate detail with textures instead.  We tend to
save lots of memory in C/C++ viewers by only creating each part once
in memory and then keeping pointers to it, instead of making a copy
for each occurance of the same brick.  I think that's harder to do
in Java, but perhaps you could manage it with a collection of parts
or a hash table.
I found it easy to do just what you describe. The J3D Scenegraph allows
it's 'Shape3D' nodes to share 'Geometry'. By using a HashTable of the
file already read in, it's relatively easy to attach the same geometry
over and over in the scene. This saves *alot* of memory (and makes
processing the files alot faster also.)

I tried this out, and you can do it too: I added some code, that shares the
geometries, and the appearances as far as possible.
Just change in the Show-class every 'SubFile' to 'Element'. The coloring
doesn't work fine at the moment, but this doesn't matter to the problem
above.

The fact is: Loading is a little bit faster, but memory is used much more
and the drawing/rotating speed gets low.

The memory you save with the sharing of geometries get exhausted by the
memory that the shapes, the transformgroups and the appearances need.

Have you looked into any of the opengl bindings for java?  GL4Java looks
pretty cool and claims to have Mac support, which would make James very
happy.
I haven't looked at GL4Java myself, but I've read many discussion on
the java3d-interest mailing list about it's pro's and con's. So far I've
been very impressed with J3D and I haven't really had to look into
anything else.

Maybe over the weekend I get a look on it.

Sascha



Message has 2 Replies:
  Re: JAVA - Viewer for dat-Files
 
"Bernd Broich" <bernd.broich@online.de> schrieb im Newsbeitrag news:GqJq1r.7G4@lugnet.com... (...) I also tried out the stripifier, that cames with j3d: A Model without stripifying needs about 34MB, with stripifying 134MB. It's very interesting. So (...) (23 years ago, 27-Jan-02, to lugnet.cad, lugnet.cad.dat.parts)
  Re: JAVA - Viewer for dat-Files
 
Bernd Broich wrote: > "Kyle McDonald" <kmcdonald@bigfoot.com> schrieb im Newsbeitrag news:3C519D02.204090...oot.com... > Hi, > for how I'm doing the internal creating: > > I did a depth search with hashing the files, create two shapes for > all (...) (23 years ago, 28-Jan-02, to lugnet.cad, lugnet.cad.dat.parts)

Message is in Reply To:
  Re: JAVA - Viewer for dat-Files
 
Hi, I'm also currently working on a very similiar program. (...) Yes because of the way .DAT files are made, the most straight forward way of representing them in J3D is 1 triangle or quad -> 1 Object. J3D however does tremendously better on both (...) (23 years ago, 25-Jan-02, to lugnet.cad, lugnet.cad.dat.parts)

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