Re: how to directly specify the perspective matrix?

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From: William Sherman -Visualization (wsherman++at++ncsa.uiuc.edu)
Date: 12/14/2001 14:14:22

Marcin,

Thanks for the advice. I will give that a try.

> The perspective matrix should only contain a perspective transformation,
> and should definitely _not_ encode the eye position, since that can lead
> to all sorts of problems, so performer does not allow specifying a general
> matrix for this transformation. What you should do to move the eye is call

I am curious to know more about the situation though. At the moment,
I'm using OpenGL with the persepctive matrix specified by Deering in
his 1992 SIGGRAPH paper describing his work on head-tracked stationary
screen displays. This seems to work fine, though if you mean by
problems that lighting and fog will be problematic, I admit I haven't
messed with those features yet. Otherwise his matrix seems to produce
a reasonable off-axis perspective images that match when lined up
with adjoining, orthogonal screens.
 
> pfChannel::setView and pass a pfFrustum to the channel that specifies only
> your field of view (or call pfChannel::makePersp)

And setView uses Euler angles, which also cause all sorts of problems,
and hence I do not use in my code.

> -- Marcin

        Thanks again,
        Bill

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