Thanks White for you response. Fortunately, Sun fixed the bug that prevented us from using a DecalGroup to accomplish this (BugId 4476109). So now everything works fine!
-Roy White Morph wrote: > 2 suggestions(maybe not practical): > > (1): leave those holes, have your background color looks like sea > > (2): write a program to find all those vertices lying on the sea(this is easy), try >to re-construct the sea using all those vertices you found(is it possible? I am not >qutie sure) > > white > > On Wed, 3 Jul 2002 10:15:41 +0200, Roger Berggren <[EMAIL PROTECTED]> wrote: > > >Hi Roy, > > > >I have thought about a similiar problem and I'm wondering > >if one solution is to move the earth surface a short distance > >away from the water sphere. > > > >I know this means you have to traverse and modify all your > >coordinates for the earth surface, but this will not take that > >much time even with large datasets (500 000+ coordinates). > > > >If you do not think that this is a solution could you please > >explain why. > > > >Roy Duffy wrote: > > > >>We have been running into a problem in Java3D for over a year now, and > >>we are looking for a better solution to the problem than we are > >>currently using. The > >>problem is this: we have a database of polygons that make up the > >>earth's surface, but just for land, not for the oceans. There is no > >>easy way using the data to > >>separate out the coastline, so we can't really generate the water > >>ourselves. > >> > >>So, what we want to do is render a high-resolution blue sphere, and then > >>render the land on top of the sphere. The two parts are coplanar (there > >>is no > >>elevation data in our dataset), so we clearly need to do something to > >>get around the Z-fighting problem. We have tried a variety of things, > >>but none of them > >>seem to work: > >> > >> 1.The correct solution would be to use a DecalGroup (since that is > >>what it was created for in the first place!!!) Unfortunately, there is > >>a known bug in > >> Java3D (BugId 4476109) that messes up the depth buffer when using a > >>DecalGroup on Nvidia cards. We > >> submitted this bug report a year ago, and it has not yet been > >>resolved. > >> 2.Our second attempt was to use an OrderedGroup instead of a > >>DecalGroup, setting setDepthBufferEnable(false) and > >> setDepthBufferWriteEnable(false). This had the exact same problem > >>as the DecalGroup attempt. > >> 3.The third attempt was to use the polygonOffset to try to bump the > >>Z-buffer value of the land to prevent Z-fighting. This was CLOSE to > >>working, but > >> there was still Z-fighting in certain spots. And besides, the > >>Java3D archives are full of messages saying "be careful with > >>polygonOffset. It works > >> differently on different graphics cards" > >> 4.The only way we were able to get it working (and I use that term > >>loosely) is to set a transparency attribute on EVERY object in the > >>scene. So, we are > >> effectively disabling the depth buffer and rendering every object > >>using alpha blending. Which means that you have some objects rendered > >>in front of > >> other objects even though they should be behind them, and even the > >>objects themselves are sometimes drawn backwards, with parts of the > >>object > >> incorrectly in front of other parts. > >> > >>So, what I'm looking for is (a) a brilliant solution to the problem, (b) > >>a kludgy solution that works better than what we have, or at least (c) a > >>better feel for > >>when (and more importantly, IF) the bug mentioned above will ever be > >>fixed. > >> > >>Thanks, > >> -Roy Duffy > >>[EMAIL PROTECTED] > >> > >>=========================================================================== > >>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". > >> > >> > >> > > > > ========================================================================== > >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". > > =========================================================================== > 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". =========================================================================== 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".
