Re: pfFrustums and pfChannels

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Jim Helman (jimh++at++surreal)
Thu, 10 Mar 94 00:36:43 -0800

   
> I am using Performer 1.1 on an Onyx RE2. I am trying to do off-axis
> perspective. How can I do this with 1.1? Is there a call like
> pfSetChanFrust(pfChannel *chan, pfFrustum *frust) which would

Doing off-axis work in 1.1 requires that you set the
channel viewpoint and FOV so that the on-axis frustum
used for culling, encompasses the off-axis frustum you
really want.

Then in the channel draw callback, set the GL matrix
perspective and viewing matrices appropriately. Here's
how 1.1 initializes them by default:

        window(winLeft, winRight, winBottom, winTop, near, far);
        mmode(MVIEWING);
        loadmatrix(ident);
        rot(-90, 'x'); /* convert from GL to Performer coords */
        {
            pfMatrix invViewMat;
            pfOrthoNInvertMat(invViewMat, ViewMat);
            multmatrix(invViewMat);
        }

rgds,

-jim helman

jimh++at++surreal.asd.sgi.com
415/390-1151

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