Hi Tor,

Tor Olav Kristensen <tor### [at] TOBEREMOVEDgmailcom> wrote:
> Woaw ! That's nice. AFAIR from the pre-beta test period for v3.5,
> it should not be possible for users to define recursive functions.
>
> But obviously this has changed since then. (Unintentionally ?)
>
>

I haven't seen this change in any of the change-logs, maybe it's an 'Easter
Egg' :-)

There's an nice variation I remembered from my days playing with Fractint,
so I went looking ...

[Mandelbrot code snipped]
>
> --
> Tor Olav
> http://subcube.net
> http://subcube.com

// start of code

#version 3.6;

#include "colors.inc"

// returns the 'potential' surface from 'Fractint'
#declare IterFn =
   function(N, Max, Bail, Slope, Re, Im, Zr, Zi) {
     select(
       N = Max | sqrt(Zr*Zr + Zi*Zi) > Bail,
       0,
       IterFn(N + 1, Max, Bail, Slope, Re, Im, Zr*Zr - Zi*Zi + Re, 2*Zr*Zi +
Im),
       min(1,select(N = Max, 0, pow(log(sqrt(Zr*Zr +
Zi*Zi))/pow(2,N),Slope), 0))
     )
   }

#declare MandelFn = function(Re, Im, Max, Bail, Slope) { IterFn(0, Max,
Bail, Slope, Re, Im, Re, Im) }

isosurface {
  function { y + MandelFn(x-0.7, z, 500, 2000, 0.6) }
  contained_by { box {-<3,1,3>,<3,0,3> } }
  max_gradient 6.5
  pigment {
    function { 1-MandelFn(x-0.7, z, 500, 2000, 0.3) }
    color_map {
      [ 0.0 color Black   ]
      [ 0.25 color Cyan    ]
      [ 0.5 color Magenta ]
      [ 0.75 color Yellow  ]
      [ 1.0 color White   ]
    }
  }
  rotate 10*z
  rotate -50*x
  translate 3*z
}

background { rgb <.5,.6,.7> }

light_source { <-2,4,0>*100 colour rgb 1 }

// end of code

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