Hi Christian,
Christian Bar wrote:
> Well, I know there is a size field, but it only works if the particle
> system is not in "point mode" (Particle::Points); in that case, every
> point has the size of the first size I put into the size field...
>
True.
> Into the related pages of the openSG 1.6 .chm file, there is a phrase
> that says: "osg::Particles::ModeE::Points are rendered as simple
> GL_POINTS. Points use the positions, colors and textureZs attributes.
> A single size can (and should!) be given, but size per particle is not
> supported (yet)."
> By the way, I did not found a page for particles into OpenSG 1.8 docs...
>
Hm, that's surprising. We'll need to look at that.
> Maybe should I use a particle system with billboards? I would like to
> use simple points because it should be faster....
> Is it correct?
>
In general yes. The problem with point sizes is that in standard OpenGL
you cannot change them inside glBegin/glEnd, so to change the point size
you have to close the begin/end loop, which is expensive. That's why the
particles don't support it.
The best solution is to use a shader, as that can change the point size
without heavy overhead.
Yours
Dirk
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