On Sat, 13 Feb 2010 20:01:51 +0100, Warp <war### [at] tagpovrayorg> wrote:
> Fredrik Eriksson <fe79}--at--{yahoo}--dot--{com> wrote:
>> Typically, the perspective transform is defined such that the resulting
>> z-coordinates fall in a suitable range (e.g. [0,1]). Clipping can then  
>> be performed without knowledge about the original clipping planes.
>
>   Ah, now that you mention that, yes, that's probably a very common
> technique. Rather than carrying around the distances of the clipping
> planes, what is done is to scale the scene so that the clipping planes
> are at distances 0 (well, almost) and 1 from the camera. This scaling
> is then undone by the perspective projection.

No, the scaling is done *by* the perspective transform.



-- 
FE

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