(I'm adding some more info from a similar e-mail Lars sent to me privately.)

Lars Paukert wrote:
> Hi,
>
> thanks for the hints again,
>
> this particles class is great i guess. But i don't know how to use it 
> propper. Do you know about any documentation, or tutorial?
>   
-- additional stuff here --
> I have been looking for it all day in the web, i can only find some 
> papers where it is briefly mentioned. And the trac opensg doc doesn't 
> really help me, it's a developer doc.
>
> As an example:
>
> As you advised to use the ViewDirQuads, i read about this and 
> understand that it perfectly suits my requirements. So I have been 
> reading all related files in order to find out what to fill in 
> ->setMode(..) to get ViewDirQuads. No success :(
Try OSG::Particles::ViewDirQuads.
>
> Am i overlooking something? It seems to me that many people know all 
> these details, but where from?
I usually look at http://www.opensg.org/doc-1.6.0/hierarchy.html or the 
source (in the order of tutorials, library tests & library code). But 
the doxygen docs are alright for 98% of my needs.

So, for the particles class: 
http://www.opensg.org/doc-1.6.0/classosg_1_1Particles.html
> I am really lost, can you give me some advise how to initialize the 
> particles? Or maybe you know a good and detailed paper about it.
Hm. Look at this test, it's a good example:

 
http://opensg.cvs.sourceforge.net/*checkout*/opensg/OpenSG/Source/System/NodeCores/Drawables/Particles/testParticlesRender.cpp?revision=1.2
> this is in my constructor:
>
>     this->pNode = Node::create();
>     this->pCore = Particles::create();
>     
>     beginEditCP(pCore);
>         pCore->setNumParticles(100);
>         pCore->setMode(2);    <- is this ViewDirQuads?
>     endEditCP(pCore);
>     
>     beginEditCP(pNode);
>         pNode->setCore(pCore);
>     endEditCP(pNode);
>
> Now i get the "couldn't find drawer"-message in the console. I mean of 
> course it cannot work, the particle-system needs much more information 
> like the position of the emitter, emitting rate, emitting direction, 
> how are particles behaving (accelerating, etc). I think i pretty much 
> know the theory about particle systems, since usually i implemente 
> them by myself. I just can't get a clue about the syntax and usage of 
> many OpenSG commands. 
The Particles class is just a container of particle positions (& 
optionally colors). It does not emit anything, there's no emitter or 
simulation in OpenSG. 

So, add something to the Position field. Remove the "setNumParticles" 
call and use getPositions.push_back() a few times. See the 
testParticlesRender.cpp I linked to above.

Also, you need a material for your particles. Try setting the material 
in the particles core to something (using setMaterial()), like the 
textured material you used previously.

Cheers,
/Marcus



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