Hi Tom, The OSG's default convention for world coordinates is for Z to be up, and typically this means local coords are also Z up. In the case of osgParticle it looks like the local coords of a particle are Y is up - please note that I'm not the original author of osgParticle so am having to interpret from the source code in front of me, much like yourself.
Perhaps the particle rotation is the thing which is messing things up. I'll will look at this aspect. Robert. On Wed, Dec 17, 2008 at 6:37 PM, Jolley, Thomas P <[email protected]> wrote: > Hi Robert, > > It's hard to describe but I'll give it a shot. When using osgviewer, > the world coordinate system is Z up. You can see that by looking at the > modelview matrix in ParticleSystem. When > ParticleSystem::single_pass_render calls Particle::render the rotation > matrix, R, in render is designed for a coordinate system of Y up. It's > trying to rotate the particle's quad about the local Z axis. It's > because the modelview matrix was not applied before single_pass_render > was called that these two coordinate systems are the same. The local > coordinate system should have been rotated by the modelview matrix. The > billboard rotates about osgviewer's Z axis (perpendicular to the camera > near plane). If the modelview matrix had been applied, the quad > rotating about the local Z axis would be parallel to the camera near > plane. > > In an application like VTP (where I think Y is up) the particles should > rotate correctly. Perhaps Ben Discoe can verify that. > > If you can apply the modelview matrix to the rotation matrix R in > Particle::render that may solve the problem. > > >> -----Original Message----- >> From: Robert Osfield [mailto:[email protected]] >> Sent: Wednesday, December 17, 2008 11:50 AM >> To: OpenSceneGraph Submissions >> Subject: Re: [osg-submissions] Particle >> systemsetInitialRotationalSpeedRange() >> >> HI Tom, >> >> The original changes back in March were there for a reason >> (to handle world scale effects), and the new code was meant >> to handle the billboards wihthout needing to reset the >> modelview matrix. I'm currently reviewing the code and the >> SmokeBox.osg example, but as yet haven't spotted where the >> bug might lie. >> >> BTW, I don't know what relevance the orientation of X,Y,Z has >> as, and hence why you mention it, as in theory a billboard >> will just rotate to be parallel to cameras near plane. Is >> there something specific that made you mention this? >> >> Robert. >> >> On Wed, Dec 17, 2008 at 2:36 PM, Jolley, Thomas P >> <[email protected]> wrote: >> > Hi Robert, >> > >> > Trying this again on osg-submissions. >> > >> > I found time to look at this problem. What you had usually >> won't work >> > because the rotation applied in Particle::render doesn't >> always match >> > what is going on in ParticleSystem::single_pass_render. It >> may work >> > for applications where Y is up, X is to the right, and Z is >> toward the >> > viewer like VTP. I'm not sure how to fix it other than >> reversing most >> > of the r7961 changes. >> > >> > I've enclosed a modified ParticleSystem.cpp with some of the r7961 >> > changes you made in single_pass_render. It looks like >> there is a typo >> > in calculating yAxis. I think it should be scaleY*scaleY >> instead of >> > scaleX*scaleY. Since I'm not sure what you were trying to do with >> > this I left that part the way you had it. >> > >> > <<ParticleSystem.cpp.gz>> >> > >> > _______________________________________________ >> > osg-submissions mailing list >> > [email protected] >> > >> http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscene >> > graph.org >> > >> > >> _______________________________________________ >> osg-submissions mailing list >> [email protected] >> http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-o >> penscenegraph.org >> > _______________________________________________ > osg-submissions mailing list > [email protected] > http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org > _______________________________________________ osg-submissions mailing list [email protected] http://lists.openscenegraph.org/listinfo.cgi/osg-submissions-openscenegraph.org
