In article <1MkG+AAk### [at] econymdemoncouk> , Mike Williams 
<mik### [at] nospamplease>  wrote:

> 9.      Rendering without anti aliassing
>
> 10.     Reducing the image size to 640x480 or less
>
> 11.     Increasing max_gradient from 5 to 6
>
> 12.     Decreasing max_gradient from 5 to 4
>
> 13.     Decreasing the accuracy from 0.0005 to 0.0006
>
> 14.     Increasing the accuracy from 0.0005 to 0.0001
>         (compare this with point number 7!)

Well, crackle uses random numbers for some things internally.  The function
is basically unsuitable for an isosurface because the root finder will have
lots and lots of problems with it simply because of the nature of the
crackle function.

Changes in resolution will *change* the intersection points and thus the
calculation of the function value, even if it is off only by a single
changed bit in the coordinate, the resulting function will be different.
The reason behind this is that crackle makes a great pattern but a terrible
function for isosurfaces!

> 15.     Moving all the #declares outside the isosurface{} block

Depending on what you do, this can also change the floating-point function
and thus changes the accuracy due to floating-point arithmetic.

> 16.     Simplifying the isosurface function.

Yes, because simplifying the function changes the accuracy due to
floating-point arithmetic.

> 17.     Removing the three blank lines between the '//+sc...' and the
>         '#include "colors.inc"' (!)

This does not make any sense at all :-(  If this would make a difference,
there would be a bug in the tokenizer that would be so serious that hardly
any scene would work at all!!!  Obviously this is not the case...


    Thorsten


____________________________________________________
Thorsten Froehlich, Duisburg, Germany
e-mail: tho### [at] trfde

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