I'm glad someone else mentioned this:)  I've noticed the same thing, and 
depending on which way you're looking, there are distinct 'ridges' or creases 
in the cloud layers, seemingly as a consequence of the reduced cloud layer 
radii.

It wasn't always this way, so I deduced that it had been done deliberately, 
some good reason.

LeeE

On Monday 22 March 2004 15:12, Curtis L. Olson wrote:
> Fred,
>
> There is a different problem with the clouds; we need to be careful not
> to get distracted with a side issue here.
>
> In the case of the clouds, the primary problem is that the shape of the
> cloud bowl is much more curved than the shape of the earth.  This means
> the elevation above ground of the clouds at some distance away is much
> lower than the elevation of the clouds at the view point.
>
> This doesn't show up much in flat areas, but you can *really* see it in
> mountainous areas.  The cloud "bowl" is centered around the view point,
> so as you fly, watch the clouds that appear in front of mountains, as
> you get closer they will raise up and the intersection point will change.
>
> This is a primarily a problem with the shape of the cloud bowl, and not
> a problem with transparency or draw order or alpha test or anything like
> that.
>
> Ideally, the curvature of the cloud bowl should closely match the
> curvature of the surface of the earth which is *nearly* flat within
> visible distances.  I would propose that a flat plane would more
> accurately match reality that our super hyper exagerated cloud bowl does
> now.
>
> The person who added the clould bowl was trying to make the clouds fade
> at the horizon, but I'm not sure this is the best way to go about it.
>
> Regards,
>
> Curt.
>
> Frederic BOUVIER wrote:
> >I noticed that at KSFO too. The problem with clouds is rather tough.
> >Without alpha-test, we wouldn't see anything above clouds from below.
> >The bottom of clouds ( the side of the quad pointing downward ) is
> >drawn before the scene and the upper side after so we can see clouds
> >through bridges or trees. This was needed before alpha test was used
> >in models ( although I think alpha-test is not used yet for trees ). We
> > can try to come back to the previous situation where all sides of clouds
> > are drawn after the scene and rely on alpha test. There will be an ugly,
> > not blended border around transparent patterns but It could be
> >acceptable if it only show up at close distance.
> >
> >We can also begin to think about a multi pass method that would :
> > 1. draw the clouds above the viewer without depth update,
> > 2. draw the scene,
> > 3 .redraw the clouds above with depth test
> >
> >With an impact on framerate due to double writing and problem like
> >the one Melchior is experiencing with overlapping semi transparent
> >objects. Haven't thought about it much of that.
> >
> >-Fred
> >
> >
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