Re: Non-symmetric fog?

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From: Andreas Ekstrand (Andreas.Ekstrand++at++saab.se)
Date: 08/21/2001 01:13:12

Hi again!

Do you mean that layered fog can be done with pfVolFog OR with
pfEarthSky? In that case, is the layered fog in pfEarthSky only
available in 2.4?

Isn't there any way to get this behaviour without multipass rendering?
Actually I don't need certain layers. I just need to control the glFog
with more that just the z value. Isn't it possible to give the glFog a
function that depends on both z and (h,p,r) to calculate its fog?

Regards,
Andreas

Radomir Mech wrote:
>
> Andreas Ekstrand wrote:
> >
> > Hi!
> >
> > I wonder if anyone knows how to implement a fog that not only depends on
> > the distance but also on viewing angle? That is, if you are at say 1000
> > metres above the ground, observing two objects, one at 500 meters and
> > one at 1500 metres but equally far from your position, one of the
> > objects could be visible and the other not.
> >
> > Is it possible to make the pfFog (or glFog) behave this way? Could you
> > solve it in some other way - callbacks maybe?
> >
> > Any comment or suggestion will be appreciated.
> >
> > Thanks in advance,
> > Andreas Ekstrand
> >
>
> Hi Andreas,
>
> you can use layered fog in pfEarthSky or in pfVolFog (in 2.4 only).
> In pfVolFog, for example, you can set fog density at certain elevation and the
> density in between is linearly interpolated. So in your case you can set density
> to 0 at 900 and to a value above 0 at elevation 800 and at elevation 0.
>
> You have to call pfVolFog::draw in the draw call back. It draws the scene twice,
> first non-fogged and then it blends each pixel with the fog color according to
> its distance from the eye and its elevation with respect to the eye.
>
> Check examples in perf/samples/apps/C/fogfly or perf/samples/apps/C++/volfog.
>
> Cheers,
> Radomir
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FDM-AE Andreas Ekstrand |E-mail: Andreas.Ekstrand++at++saab.se
Saab AB                 |Phone:  +46 (0)13 - 18 40 42
SE-581 88 Linkoping     |Fax:    +46 (0)13 - 18 41 77
SWEDEN                  |
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