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 =================================================== =========================================================================== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA3D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
