I can confirm the bug outlined below.  There is no workaround known at this
time.  Note that this bug may "look" slightly different on different
platforms, or it may not show up at all.

    Thorsten, POV-Team

----------
>From: "Alun" <tho### [at] lineonenet>
>Newsgroups: povray.general
>Subject: Problem with multiple f_hetero_mf isosurfaces
>Date: Mit, 10. Sep 2003 15:56 Uhr
>
> I'm creating a scene with two isosurface objects that use similar
> f_hetero_mf functions - one for a jagged looking mountain range
> in the distance, and one for some smoother rolling hills in the
> foreground.
>
> I'm happy with the function for the mountains, so I copy it to use
> as the basis for the hills. At this point I've got a scene with 2
> identical isosurfaces.
>
> So far so good :-)
>
> To make the hills smoother than the mountains, I change the number
> of octaves in the f_hetero_mf function in the hills isosurface,
> and re-render...
>
> This is where it all goes wrong :-(
>
> The hills isosurface changes correctly, but the mountains one also
> changes - and not always in the same way, for some hills_octaves
> values it changes to a copy of the hills, for others it fills its
> container volume, and for others it doesn't change at all.
>
> I know this sounds like I'm doing something daft, but I've
> simplified the scene right down, and I can't see anything wrong
> with it.
>
> Could someone out there have a look at this and let me know if I
> am doing something daft ?
>
> Here's my cut down scene:
> ---------------
> #version 3.5;
>
> #include "functions.inc"
> //
>
----------------------------------------------------------------------------
---------
> --
>
> #declare mountain_octaves=12;
> #declare hills_octaves=12;     // Try changing this to 4 ...
>
> //
>
----------------------------------------------------------------------------
---------
> --
>
> camera {
>   right x*image_width/image_height
>   location  -10*z
>   look_at   -y/2
>   angle 30
> }
>
>
> light_source { 2*y-z rgb 1 }
>
> //
>
----------------------------------------------------------------------------
---------
> --
>
> isosurface {
>   function { 2+y - f_hetero_mf(0.2+x,0,z, 0.9, 1.7, mountain_octaves, 0.5,
> 0.9, 3 ) }
>   contained_by { sphere {0 1} }
>   evaluate 5, 1.2, 0.95
>   pigment { rgb <0.7,0.8,0.9> }
>   translate x*1.2
> }
>
> //
>
----------------------------------------------------------------------------
---------
> --
>
> isosurface {
>   function { 2+y - f_hetero_mf(0.2+x,0,z, 0.9, 1.7, hills_octaves, 0.5, 0.9,
> 3 ) }
>   contained_by { sphere {0 1} }
>   evaluate 5, 1.2, 0.95
>   pigment { rgb <0.5,0.8,0.6> }
>   translate -x*1.2
> }
>
> //
>
----------------------------------------------------------------------------
---------
> --
>
>
>
>


____________________________________________________
Thorsten Froehlich
e-mail: mac### [at] povrayorg

I am a member of the POV-Ray Team.
Visit POV-Ray on the web: http://mac.povray.org

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