Luca Masera said:

> Hi everyone,
> I've added a particle system to FlightGear that simulates the smoke via a
PLIB object 
> (I adapted the class ssgaParticleSystem to meet some requirements). 
> However, I've in trouble with billboarding. Used alone, with a PLIB's
example, the code 
> that rotates the particles following the user movement's works right. In
> instead, that code doesn't works and the particles follows the user only
within a small 
> range of rotations (they move like the lens flare...).
> I think that the bug is into the code of rotation: it uses the MODELVIEW
matrix, that 
> maybe doesn't works with the lookAt and lookFrom. 
> There's a way to get the position and the rotation of the view (I've tried
about all the 
> methods into the class FGViewer, but even when the view is rotated the data
> change). If I could get them maybe I'll able to correctly rotate the 
> particles.

Hi Luca,

It may help for you to explain more about what you are trying to do.  Is this
exhaust smoke from a moving aircraft model?  Probably I'm the one to help you
since I rewrote most of the viewer a couple years ago,  but I just don't
understand what you are asking.

This is may not help, since I am guessing about what you are trying to do, but
take a look at the code in SimGear/scene/model to see how to place an ssg
object (ssgBranch) in the scene.  This can be used for both stationary and
moving objects.

Is there anyone on the list who can translate to and from italian?  Maybe that
would help.



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