Hi Tom, Which version of the OSG are you using in your tests?
Robert. On Wed, Apr 22, 2009 at 6:35 PM, Jolley, Thomas P <[email protected]> wrote: > Hi Robert, > > A little late but I just noticed this change has broken particle effects > in my application. When I tried to change my application to work with > this change I get problems with floating point precision on the > particles. I don't think this change is the correct solution for fixing > floating point precision problems with particle effects. It's better > done at the application level by separating out non-particle system > nodes, particle processors, and the geodes where particles are placed. > An appropriate MatrixTransform can be placed above each new graph to > resolve the precision issues for the particular frames of reference. > Perhaps Tim Moore can explain further the problem he was trying solve by > giving us an example. > > Here are some examples of how this change looks like it might work and > how it doesn't work using the cessnafire.osg model. > > 1. How it looks like it might work. Load the cessnafire.osg model and > put it under a MatrixTransform. Using the MatrixTransform, move the > model to about 6M meters. Watch the particle effects when the model is > slowly translated using the MatrixTransform. The precision of the > particles look good. The particles are emitted from the correct > location from the model. The particles once emitted move with the > MatrixTransform when they should stay fixed to the world coordinate > system. > > 2. How it doesn't work. Load the cessnafire.osg model and put it under > a MatrixTransform. Put the MatrixTransform under a Group. Move the > Geodes where particles are placed so that they are under the top Group > node. You may as well move the ParticleSystemUpdater under the top > Group node. Moving the model out to 6M meters and slowly translate the > model using the MatrixTransform. The precision of the particles is bad. > The particles are emitted from the correct location but possibly the > wrong direction due to precision problems. The particles once emitted > stay fixed to the world coordinate system as I would expect. > > > -----Original Message----- > From: Robert Osfield [mailto:[email protected]] > Sent: Thursday, September 18, 2008 5:12 AM > To: OpenSceneGraph Submissions > Subject: Re: [osg-submissions] osgParticle ParticleSystem and > ModularEmitterin different coordinate systems > > Thanks Tim, I've merged your changes, and also added a > Drawable::getWorldMatrices(const Node*) method and tweaked your code to > use this rather than needing to use getParents(0) and then > getWorldMatrices() as getParents(0) could in theory be null (although in > a correctly set up scene it won't be). > > Could you do an svn update and test out my changes, Robert. > > On Wed, Sep 10, 2008 at 9:39 AM, Tim Moore <[email protected]> wrote: >> Hello, >> This submission fixes a bug when the ModularEmitter and ParticleSystem > >> are in different frames of reference. Specifically, it supports the >> case where the ParticleSystem is not in the world frame. One way this >> can come up is if your world coordinate system is Earth-centric; the >> float coordinates of particles don't have enough precision to avoid >> terrible jitter and other rendering artifacts, so it's convenient to >> root the particle systems in a local Z-up coordinate system that gets > moved around from time to time. >> >> I haven't touched the rotation and angular velocity properties of > particles. >> IMHO they are pretty broken, dealing in Euler angles and such, and I >> see that they aren't used in the rest of the particle system code. >> >> Tim >> >> _______________________________________________ >> 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-openscenegr > aph.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
