Ok, I will try to exclude some bricks when I am in a tunnel for testing, thank you Robert.
-----Message d'origine----- De : [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] De la part de Robert Osfield Envoyé : lundi 6 octobre 2008 12:08 À : OpenSceneGraph Users Objet : Re: [osg-users] PrecipitationEffect how to catch and modifyparticles Hi Matthieu, Switching the effect off under terrain is not straight forward as the effect is achieved by creating a repeating regular grid of bricks of particles. Each brick is actually just a single geometry that the shader uses coord data to position in its final place. This technique provides the means for an effectively infinite number of particles. The draw back is that you can't easily tailor the pattern of precipitation. Possible routes for tailoring the precipitation pattern would be to modify the technique so that is only placed bricks where you wanted them, or excluded them for regions you define. This could provide a course grained exclusion, further on from this you could possible come up with individually sculpted bricks that have the particle line segment end at a desired position. This is not a trivial modification, but should be possible. The other route you could possible take is to just switch off the precipitiation effect completely when the viewpoint goes inside the tunnel. Finally you might be able to use the stencil buffer to switch off the writing of particle fragments inside the region of interest. Robert. On Mon, Oct 6, 2008 at 10:41 AM, Matthieu DIRRENBERGER <[EMAIL PROTECTED]> wrote: > Hello, > > > > I am using osgParticle::PrecipitationEffect to add snow or rain on my scene. > > I am looking at a way to determine for each particle, if z position is under > the terrain or not. > > The objective is, when a particle is under an object or in a tunnel it > should not be visible... > > > > In a first time I saw ParticleSystemUpdater but I don't know if it can work > with PrecipitationEffect... > > I thought about a shader to do that, but I think I can do that simply with > the accept/traverse methods. > > I suppose I must implement a callback method, called by the visitor, but I > don't understand how to implement that visitor with PrecipitationEffect. > > > > Can you give me some help? > > > > Thanks a lot. > > > > Regards, > > Matthieu. > > > > _______________________________________________ > 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
