Troy Stephen (troys++at++wormald.com.au)
Thu, 27 Mar 1997 09:56:48 +1111 (EST)
We had the same problem with our application using a similar configuration
and FOV as you. My guess is that the polygons which performer renders to
emulate the sky and horizon are getting clipped by the far clipping plane
and what you are seeing is uncleared pixels in the frame buffer.
To solve this problem in our application I disregarded pfESky and
implemented our own Earth-Sky model by creating a tent which is positioned
such that it's peak is above the eyepoint and always follows the eye
around the database. The size of the tent must be carefully calculated
so that it is never clipped (even when the eyepoint rolls).
The roof of the tent forms the sky and it's sides are used to simulate
the horizon. With a bit of work you can even simulate directional horizon
glow which will look neat at dawn and dusk.
Each frame, the first thing you should do is a TAG CLEAR of the frame
buffer, then draw your tent, then draw everything else in the scene.
Sorry, I couldn't give you a quick-and-dirty solution, but if you decide
to head down this path, in the long run you will end up with a really nice
atmospheric model.
Good Luck,
Troy Stephen
On Tue, 25 Mar 1997, Julia Ellery wrote:
> To anyone,
>
> We have come across a problem with multichannel use that we think may be
> due to the EarthSky model.
>
> When we have a large roll, the off centre channels do not appear to
> clear properly and a staggered layering effect is seen.
>
> If we remove our call to pfChanESky then all seems ok.
>
> We have 3 channels with the side channels offset by +/- 45 degrees.
>
> Does anyone know what is going on and if so, what we can do to get round
> it? We need the EarthSky model for fog effects and also for real-time
> sky colour changes.
>
> Thanks,
>
> --
>
> Regards,
>
> Julia Ellery,
> Senior Visual Software Engineer,
> Intersim Limited, Units 7-8, Thorgate Road, Littlehampton. Sussex. UK
> Tel: +44 (0)1903 733428 Fax: +44 (0)1903 730246
> email: modellers++at++intersim.co.uk Internet: http://www.intersim.co.uk
>
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