I have been working with tiled height_fields with
an image function applied.  I am having difficulties
getting consistent and predictable outcomes.  I'm
fear I've taken it as far as my feeble
brain cells can go.

I have assembled a summary of my trials
and questions here:
http://www21.brinkster.com/jrcsurvey/temp/index.htm

If anyone can shed any light on any part of this either by
explaining the underlying factors or just by offering
a little coaching, I would really
appreciate it.

-Jim

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Jim Charter <jrc### [at] msncom> wrote:
> http://www21.brinkster.com/jrcsurvey/temp/index.htm

  In case 1 you are creating a box on the xz plane and applying the
function pattern directly to it, ie. the function pattern is being
read from the xz plane.

  The heightfield, however, is created on the xz plane but its height
is read from the xy plane.

  I think that in case 2 you have to call the function in the same way
as you are calling it for the boxes in that case, ie. not
"Fn_Pattern(x+X,z+Z,y)" but "Fn_Pattern(x+X,y+Z,z)"

-- 
                                                          - Warp

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Warp wrote:
> Jim Charter <jrc### [at] msncom> wrote:
> 
>>http://www21.brinkster.com/jrcsurvey/temp/index.htm
> 
> 
>   In case 1 you are creating a box on the xz plane and applying the
> function pattern directly to it, ie. the function pattern is being
> read from the xz plane.
> 
>   The heightfield, however, is created on the xz plane but its height
> is read from the xy plane.
> 
>   I think that in case 2 you have to call the function in the same way
> as you are calling it for the boxes in that case, ie. not
> "Fn_Pattern(x+X,z+Z,y)" but "Fn_Pattern(x+X,y+Z,z)"
> 
Thanks for the reply, Warp

That produces a different, but still scrambled, result:
http://www21.brinkster.com/jrcsurvey/temp/reply.htm

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Jim Charter <jrc### [at] msncom> wrote:
> That produces a different, but still scrambled, result:
> http://www21.brinkster.com/jrcsurvey/temp/reply.htm

  It looks to me that the pattern in the heightfield is mirrored with
respect to the y axis for some reason.

  Try using this: Fn_Pattern(x+X,(1-y)+Z,z)

  I don't know why POV-Ray would be taking the function values with a
mirrored y. Perhaps it's a bug.

-- 
                                                          - Warp

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Warp wrote:
> Jim Charter <jrc### [at] msncom> wrote:
> 
>>That produces a different, but still scrambled, result:
>>http://www21.brinkster.com/jrcsurvey/temp/reply.htm
> 
> 
>   It looks to me that the pattern in the heightfield is mirrored with
> respect to the y axis for some reason.
> 
>   Try using this: Fn_Pattern(x+X,(1-y)+Z,z)

It's a beau_tee_ful thang!!!  Thanks so much Warp.
http://www21.brinkster.com/jrcsurvey/temp/reply.htm

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Warp wrote:
>  I don't know why POV-Ray would be taking the function values with a
> mirrored y. Perhaps it's a bug.

No, no, during beta-testing, when this was pointed out, Thorsten was very 
insistent that this was the correct behavior. I remain unconvinced, though 
ultimately, it's a matter of what you *think* is most logical. It does give 
a lot of trouble and confusion though.

Rune
-- 
http://runevision.com

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