Hi,
I'm using the obj file loader. I export it from 3DS with the max2obj plugin and I haven't found any problem.
I got another question about loader : does the vrml97 loader creates behavior that creates interactivity, for example : a VRML file which programs an animation when a object is clicked ?
Thanks and enjoy 3d programming
Matthieu Beghin
Wolfgang Kienreich <[EMAIL PROTECTED]> a écrit :
Hi Brad, Hi Olaf!
First, greetings to all the members of this group. I've just signed up and
I'm glad I've finally found some people to discuss J3D mysteries with.
For a living, I'm doing research in knowledge visualisation, consequentially
focussing on 2D graphics. But privately I've been developing 3D games and
demos for a long time. Currently, I've got a project running under Java3D
... I know how the outcome should look like ... check www.ig3.de and you'll
see. Be sure I'll be back with all kind of questions, and hopefully I'll be
able to answer some of them myself.
Regarding loaders:
I would advise some caution, at least with the native loaders sun is
providing. I've recently played with the obj file loader and found it to
have several serious problems. For example, if no g tag grouping information
is given in the obj file, only one Shape3D is generated, even if multiple
materials and textures have been used in the model. This of course results
in a single Appearance being created, and only the first texture being used.
So either you have a 3D converted which breaks a model down into g tags
based on material usage on export, or you manually resolve this in the obj
file. Regarding the Lightwave loader, I personally decided to forget about
it. There are many versions of Lightwave (I'm using 6.0) and the loader
doesnt even state which versions it can load. When trying, I found out that
exporting back to 5.5 allowed my files to be loaded, but textures and
materials never were displayed.
Now for some questions:
One of my current problems is the generation of shadows. I know about
dynamic shadow maps, and about the trick published by Roettger, Iron and
Ertel on using the Alpha buffer in the absence of a stencil buffer (as is
the case in Java3D). Problem is, this method is computationally intensive
and introduces a lot of workaround code when implemented in Java3D. I'm
considering another option, namely rendering planar shadows in 2D onto
shadow map textures in a cubic texture mapping environment (precaluclate
flat shadow image, use 2D rotation and shear dependent on light position to
calculate shadowmap) as I'm mostly interested in self-shadowing of spaceship
components. Any ideas on how to achieve nice shadows with low cost?
Another problem: I'm using dot3 bumpmapping and I've been trying for some
time to combine it with object color and texture within just two texture
stages. Btw, thanks to j3d.org for explaining. It nearly works now:
bumpmapping goes into the first stage, then the second stage uses
interpolation to add (texture * objectcolor)+ (bumpmap*(1-objectcolor)) with
the bumpmap being inverted first by usign ONE_MINUS_SRC_COLOR. However, the
effects are hard to control, I would require a method for scaling down the
bumpmap to avoid shaded areas to be highlighted too much by the bumpmap. Is
there *any* possibility to control what happens inbetween texture stages?
Still more problems: When using dot3 bumpmapping, it seems that something
bad happens at the edges of the bumpmapped texture: When repeating the
bumpmap along s and t, I get nasty borders, and even when clamping it
exactly to [0,1], the borders are still there. I know about texture borders
and this is not the problem. I've even tried switching off dot3 bumpmapping
and using the texture in question in a replace combine mode just to see what
happens ... borders disappear in that case, so I'm pretty sure bumpmapping
is causing the problems. Any ideas on this?
Finally, for some input: I found out the very hard way that for texture
states to work, the texture coordinate assignment array *must* be filled,
because by default, it does not point to coordinates for all but the first
texture stage (instead of defaulting to stage 0 coordinates). The people out
there who have provided texture stage tutorials always use hardcoded
geometry where the coordinate assignments are done, but I started my
experiments with geometry loaded by the obj loader and spent some hours
finding out that texture coordinate assignments do not default to stage 0
coordinates. HTH.
Thats it for now, thanks a lot ( for you patience with me :-) )
Wolfgang Kienreich
===================================================
Wolfgang Kienreich
Knowledge Retrieval/Knowledge Visualization
Know-Center
Inffeldgasse 16c, 8010 Graz, Austria
Email : [EMAIL PROTECTED]
Tel: +43 316 820918 843 Fax: +43 316 873 5688
The program for I-KNOW '02 is now available at
http://www.i-know.at
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