pfChannel and frustum

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AnitaKishore (kishore++at++electrogig.com)
Mon, 19 Jun 1995 16:16:37 -0700

On Jun 19, 3:22pm, Jim Helman wrote:
> Subject: Re: Performer /GL camera
> When possible, it's better to set the Frustum on the pfChannel
> than setting up a camera with GL.
>
> rgds,
>
> -jim helman
>
> jimh++at++surreal.asd.sgi.com
> 415/390-1151
>-- End of excerpt from Jim Helman

Thanks Jim for responding.

As suggested by you, I am trying to set up a channel using
pfMakePerspFrust OR pfMakeOrthoFrust as follows:

Using the following, I am able to view my graphics:

pfChanNearFar(chan, 1.0f, 10000.0f)
pfChanFOV(chan, 140.0f, -1.0f)
pfSetVec3(view.hpr, 0, 0, 0)
pfSetVec3(view.xyz, 0.0f, -50.0f, 60.0f)

Next, I convert the above representation so as to use pfMakePerspFrust
as follows:
x = near * tan(140/2) where, near = 1.0
z = near * tan(131.0724/2) (this angle I got out of pfGetChanFOV for the
                             first type of setting)
Then,
pfMakeTransMat(m1, 0.0f, -50.0f, 60.0f)
pfMakePerspFrust(chan, -x, x, -z, z)
pfChanViewMat(chan, m1)

The second type of setting which uses pfMakePerspFrust doesn't work.
Can anyone tell what is wrong with the above?

thanks
-anita

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