>>This one took over 9.5 hours to render instead of 8. But hey, I guess
>>I'm the only person who finds any of this exciting, so maybe I'll stop
>>posting...
> 
> Don't stop!

OK. :-)

> It would make a great textbook cover.

Where do you think I got it from? ;-)

(Well... actually it was a colour plate inside a book about fractals. I 
forget which one - might even be BOF.)

> Have you posted a source?  I'm trying
> to think how you do this as an isosurface.  Do you manually do several
> iterations?  (Without a logic-loop in isosurfaces, this would seem
> difficult to do "elegantly.")

Oh, it is NOT elegant!

You *can* have a logic-loop in an isosurface - but it gets evaluated at 
PARSE TIME, not RENDER TIME. Just do something like this:

#macro MyFunction(x, y, z, Iter)
   #if (Iter>0)
     MyFunction(x, y, z, Iter-1) - MyFunction(x, y, -z, Iter-1)
   #else
     sin(x) + cos(y) + tan(z)
   #end
#end

(Actually, the quadratic mapping is a tad more difficult to do then 
that, but it shows the principle. Don't try to render it BTW - it 
probably looks rubbish!)

Enter "MyFunction(x, y, z, 7)", and once parsing is complete, it's as if 
you really typed in the sin(), cos(), tan() functions 128 times... (And 
POV-Ray has to recompute them that many times... slow, slow, slow!)

. . .

In case you're interested... I'm currently waiting for another render to 
finish. This time it's a 3D slice of the (4D) cubic Mandelbrot set. (Or 
rather, the set M+; the actual Mandelbrot set is the intersection of M+ 
and M-, but it's going quite slow enough as it is, thanks!)

Render time so far is 4 days, 5 hours, 41 mintes - 52% complete. Has 
loads of isosurface faults, but I'm NOT turning the max_gradient up any 
higher!!!

Andrew @ home.

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