On Thu, 2009-04-23 at 10:56 -0600, Ron Jensen wrote:
> On Thu, 2009-04-23 at 11:56 -0400, Patrice Poly wrote:
> > > nope, same behaviour!!
> > >
> > > i think that on my "slow" PC, your ridge lift is sometimes initialised a
> > > little to early (while position is 0,0,0 maybe), resulting in some nan
> > > in the result of terrain scan, wich lead to a "nan" in
> > > /environment/ridge-lift-fps.
> > >
> > > and as it's used to compute the next aircraft position, nan go all along
> > > the calculs...
> > >
> > > i tested :
> > > _ridge_lift_fps_node->setDoubleValue( 0 );
> > >
> > > and no more nan, all the properties in ridge-lift are now valid.
> > >
> > > jano
> >
> > Jano, may I ask you to do a little experiment ?
> >
> > As you have a machine which triggers the error, maybe you could try this:
> >
> > comment out all the formulas, and replace them by a nice constant, all over
> > the file.
> > Then, from bottom to top, and one by one, put the original calculations
> > back.
> >
> > Maybe that could help focus on the one that produces the bad thing ?
> >
> >
> > Then, you could also try the following ?
> >
> > line 231 : if (timer >= 1.0 ) {
> >
> > this waits 1 second before doing a scan, maybe
> > * this could be raised to a longer time ?
> > * this could be replaced by something that tells us for sure the scenery is
> > here,the plane is placed, and that get_elevation_m is ready to work ?
> >
> > I'm blind here for these experiments...
>
> Adding a test for NaN will prevent (or at least mask) the problem:
>
> strength = lift_mps * SG_METER_TO_FEET ;
> if(isnan(strength)) strength=0;
> _ridge_lift_fps_node->setDoubleValue( strength );
>
>
> We could add some debug printing, too perhaps:
if(isnan(strength)){
SG_LOG( SG_EVENT, SG_ALERT, "Ridge lift strength is NaN = " << strength
);
strength=0;
}
_ridge_lift_fps_node->setDoubleValue( strength );
SG_LOG is preferred over cout...
Ron
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