Todd -- two-sided lighting and alpha blending are two completely separate and orthogonal OpenGL state items. They work together. One does not disable the other.
(Note that if you're rendering, say, a tri strip that is transparent, and it wraps around so that a single strip shows both back and front faces, you'll need to deal with this somehow so that it is properly depth-sorted. Multiparenting and face culling with render bins is one option. But this would be an issue regardless of OSG version.) Does your 2.4 app break similarly if you enable two-sided lighting? Can you write a small/simple standalone reproducer code that exhibits this behavior? Paul Martz Skew Matrix Software LLC http://www.skew-matrix.com +1 303 859 9466 -----Original Message----- From: osg-users-boun...@lists.openscenegraph.org [mailto:osg-users-boun...@lists.openscenegraph.org] On Behalf Of Todd J. Furlong Sent: Friday, June 05, 2009 2:38 PM To: OpenSceneGraph Users Subject: Re: [osg-users] Transparency Issues Robert, Thank you for the suggestions. I didn't see a big difference in the OSG files, but I did find the cause: operator error. In the script that runs the 2.8-1 application, we were enabling two-sided lighting. So, now my question is: how do I fix transparency when two-sided lighting is enabled for a scene? I think we're lucky in that the models we have that require two-sided lighting aren't the same ones that have transparent objects. But it would be nice to understand the phenomenon. -Todd Robert Osfield wrote: > Hi Todd, > > I can't say why your are having problems with transparency in 2.8.1 vs > 2.4, as depth sorted/transparent bin hasn't changed between these > versions. Perhaps a subtle difference in the loader has caused the > difference, or perhaps there is something undefined in your data that > the two versions behavior differently with. It's a bit of a case of > hunting for a needle in a hay stack so you'll need to try and isolate > the different possibilities. > > Try converting your data to .osg and see if the two different versions > behave differently with this, even bettern convert the .ive to .osg > using 2.4, then do the same with 2.8.1 and then have a look at the > differences, if they are effectively the same then go have a look .osg > file to make sure that the objects that you think are transparent are > correctly assigned, and also check to see if all the geometries have > vertex, normal and colour arrays as required by the state setup in > your scene graph. > > Robert. > > > > On Fri, Jun 5, 2009 at 1:28 PM, Todd J. Furlong<t...@inv3rsion.com> wrote: >> I'm not sure if this is related to the "transparency problem" thread, >> so I thought I'd start a new one. >> >> We have an osgUtil::SceneView - based application that uses VR >> Juggler for rendering on a visualization cluster. Our previous >> version was built with OSG 2.4, and now we are using OSG 2.8.1. >> >> We also have a set of IVE files created in OSG 2.4. Transparent >> objects >> (non-textured) were placed in the transparent bin on conversion to >> IVE, and those objects render fine the OSG 2.4 version of our >> application. In the OSG >> 2.8.1 version of the application, we are getting mixed results: >> Sometimes transparency is OK, but other times the transparent objects appear opaque. >> Sometimes, different nodes of the cluster will render geometry >> opaque while others render it transparent. >> >> Is this related to depth sorting? What has changed between OSG >> versions that might cause this? And can I correct it easily to get >> transparent objects working again? >> >> Thanks, >> Todd >> _______________________________________________ >> osg-users mailing list >> osg-users@lists.openscenegraph.org >> http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph >> .org >> > _______________________________________________ > osg-users mailing list > osg-users@lists.openscenegraph.org > http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph. > org _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org _______________________________________________ osg-users mailing list osg-users@lists.openscenegraph.org http://lists.openscenegraph.org/listinfo.cgi/osg-users-openscenegraph.org
