> Concerning the idea itself, as someone already mentioned, single precision
> is not much faster than double (although memory use is lower of course)
> and therefore it would be only much difference if it used new features
> like 3D!Now which would be problematic for portability reasons.

3D!Now and other features make PovRay realy faster ( 50%++, but more then
200% is possible) and I said that you should choise ( in the programm
itselfs, at runtime ) to use fast single precision or slow double precision.
Every new AMD & Intel processor supports SIMD instructions ( SIMD = single
instruction multible data, e. g. 3D!Now or SSE ) and if the processor
doesn't supports this you must not use them. For example if you have an
Pentium II which doesn't have 3D!Now or SSE then the programm ( PovRay )
don't let you render the scene with single precision. I know this looks like
a lot of work, but I don't think so. I did not need 30h to convert most of
the colour calculation of PovRay from "normal" to 3D!Now. I would do the
"fast" version for 3D!Now, 3D!NowEx, SSE and SSE2 alone, that is no problem
for me. And the support is no OS problem, just the processor must support
the instruction and if it doesn't you can always render with double
precision. I hope you can understand, because my english is not so good.

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