I think Duane means with a quadrilateral transform. As you know 
better than I a 4x4 homogenous coordinates matrix can represent at 
least the computer version of perspective for vertices ...

Cheers,

Alan

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At 12:22 PM -0700 6/7/01, Andreas Raab wrote:
>Duane,
>
>>  Unfortunately, you can't represent a true perspective
>>  projection with just a 4x4 transform.
>
>Err ... what exactly do you mean by a "true" perspective projection?!
>
>Cheers,
>   - Andreas


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