andrel <a_l### [at] hotmailcom> wrote:
> On 29-Dec-08 23:58, Warp wrote:
> > clipka <nomail@nomail> wrote:
> >> So yes, that should do: A loop typically taking less than two iterations (the
> >> most expensive part probably being the RNG) and a square root. Quite
> >> inexpensive after all.
> > 
> >   When you project the point to the hemisphere, you'll probably need three
> > multiplications and a square root. That's going to be much more expensive
> > than the RNG. (High-quality RNGs are very fast. They are faster than a LCG,
> > which consists of one integer multiplication and addition.)

> but sin and cos are (much?) more costly than sqrt and multiplication is 
> comparatively negligible.

  I was commenting to his estimation that the RNG would be the most
expensive part of the calculation. Certainly not true. I would estimate
that one single sqrt() call will be several times slower than pulling a
value from a high-quality RNG.

-- 
                                                          - Warp

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