[Fwd: World to screen coord transforms]

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Lawerence Bertoldi (lberto++at++sgi.com)
Tue, 09 Jun 1998 08:30:09 -0400

There was a discussion abuot this just reciently here. The attached
message is the sumation of the discussion.

Hope it helps.

SeeYa
Lawrence
~;-}>

attached mail follows:

Date: Sat, 14 Mar 1998 16:29:52 -0800
From: hatch++at++hell.engr.sgi.com (Don Hatch)
To: Angus Dorbie , "Volz, Bill (wrvo)"
Subject: Re: World to screen coord transforms
The channel viewing matrix converts from eye space to world space,
so you'd need to multiply by the inverse
of the viewing matrix, not the viewing matrix itself.
(note that the matrix is orthonormal, so inverting it is easy.)

> This gives you a point in eye space but not yet in
> screen space. You must then transform the point through the projection
> matrix of the channel frustum to give a projected screen coordinate
> (nominally -1 to 1) which simple arithmetic will convert to viewport or
> screen coordinates.
>

Don

-- 
Don Hatch  hatch++at++sgi.com  (415) 933-5150  Silicon Graphics, Inc.
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