Hey, anybody considered using SIMD instructions embeeded in
new-generations of processors??
As far as i know, MMX is worthless, but there are some neat SIMD
features in new P-III processors that could help.

Now, one of things that costs time to compute is dot-product. And dot
product is something that is being used *a lot* in raytracing , to say
at least. 

As far as i remember from peering into POV-Ray's source code, it's using
"double" floating-point numbers. That's something like ~90 bits of
precision.

If we could get by using ordinary 32-bit "float" precision, we could
take advantage of SIMD-capabilities of P-III processor and speed up
dot-product calculations substantially.

Now did anyone tryed this trick before??

As soon as i get some time , i'll try to convert POV-Ray dot-product
algorithm to SIMD and take a look at the results. It's hard to say how
it will look like , but my guess is that we don't need additional
precision of "double" variable too often.

Any input is welcome!

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