Re: Asymmetric Frustrum

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george williams (gcw++at++best.com)
Tue, 01 Jul 1997 13:34:42 -0700

pfMakePerspChan is indeed the right call to use here. Note that the default
viewpoint in Performer is as follows (quoted from the Performer Programmer's
Guide, p.95.) : The default viewpoint is at the origin (0,0,0) looking
along the +Y axis, with +Z up, and +X to the right.
So, without transforming the eye point and view direction, 'left' and
'right' correspond to X dimension/ 'bottom' and 'top' correspond to Z
dimension. Also, note that the default eye position still lies along the Y
axis after creating an assymetric viewing frustum.

George Williams
Fakespace, Inc.

At 02:35 PM 7/1/97 +0000, you wrote:
>We run Performer 2.1 on a Onyx2 IR and need to use asymmetric
>frustrums. Man pfChannel seems to suggest to use
>pfMakePerspChan(pfChannel* chan, float left, float right, float bottom,
>float top). I couldn't figure out what coordinate system to use for
>left,right,top and bottom though. The example in the manpage seem to
>suggest fractions of the total FOV but how to set this? Calling
>pfChanFOV didn't seem to make a difference.
>
> Dr. Hendrik-Jan van Veen
>
> Max-Planck-Institute for Biological Cybernetics
> Spemannstrasse 38 72076 Tuebingen GERMANY
> tel: +49-7071-601-631 fax: +49-7071-601-616
> e-mail: veen++at++mpik-tueb.mpg.de
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