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In article <38bcf2c7@news.povray.org>, Nieminen Juha
<war### [at] sarakerttunen cs tut fi> wrote:
> Isn't there some kind of proximity patch? Can't it be used for
> displacement calculations?
I wrote a proximity pattern which is included in MegaPOV, it calculates
a value which depends on the distance from the surface of an object by
shooting rays at it...I am not sure how good it would be for
displacements though. It might just be too slow for an isosurface,
unless it could be calculated once and output as a density file.
--
Chris Huff
e-mail: chr### [at] yahoo com
Web page: http://chrishuff.dhs.org/
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On Wed, 01 Mar 2000 07:18:37 -0500, Chris Huff wrote:
>In article <38bcf2c7@news.povray.org>, Nieminen Juha
><war### [at] sarakerttunen cs tut fi> wrote:
>
>> Isn't there some kind of proximity patch? Can't it be used for
>> displacement calculations?
>
>I wrote a proximity pattern which is included in MegaPOV, it calculates
>a value which depends on the distance from the surface of an object by
>shooting rays at it...I am not sure how good it would be for
>displacements though. It might just be too slow for an isosurface,
>unless it could be calculated once and output as a density file.
Obviously, creating a density file from an object is trivial. Once you
have that, you can relatively easily perform a filter of some kind that fills
in the voxels with a number corresponding to their distance from voxels
containing the surface of the object, then build an isosurface with that.
But it'll take lots and lots of memory, probably more than the mesh.
--
These are my opinions. I do NOT speak for the POV-Team.
The superpatch: http://www2.fwi.com/~parkerr/superpatch/
My other stuff: http://www2.fwi.com/~parkerr/traces.html
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On Thu, 24 Feb 2000 22:44:23 +0200, Peter Popov wrote:
>With time I've compiled a list of features I would be happy to see in
>POV-Ray. I think it wouldn't hurt if I posted it here.
I'd like to add one to the list:
scale_map
If not used scale an object as normal, but if used eg.
box{
<-1,-1,-1>,<1,1,1>
pigment {Blue}
scale_map {
gradient y
[0.0 1 ]
[0.25 1 ]
[0.26 0.75 ]
[0.74 0.75 ]
[1.0 1 ]
}
}
it'd pinch the object in at the center, all the way round, being scale 1 at
y*1 scale 0.75 from y*0.5 to y*-0.5, and would be back at one again from there
to y*-1.
It'd be really good if you could add more than one of these to an object, and
hopefully be able to add them to CSG objects not only single primitives.
I've thought about this many times, and hope it's a viable addition to the
current features in POV/MegaPOV.
--
Cheers
Steve email mailto:sjl### [at] ndirect co uk
%HAV-A-NICEDAY Error not enough coffee 0 pps.
web http://www.ndirect.co.uk/~sjlen/
or http://start.at/zero-pps
12:17am up 5:22, 3 users, load average: 1.00, 1.00, 1.00
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Chris Huff wrote in message ...
>In article <38bcf2c7@news.povray.org>, Nieminen Juha
><war### [at] sarakerttunen cs tut fi> wrote:
>
>> Isn't there some kind of proximity patch? Can't it be used for
>> displacement calculations?
>
>I wrote a proximity pattern which is included in MegaPOV, it calculates
>a value which depends on the distance from the surface of an object by
>shooting rays at it...I am not sure how good it would be for
>displacements though. It might just be too slow for an isosurface,
>unless it could be calculated once and output as a density file.
Use eval_pattern() or eval_pigment() on the proximity pattern to scan the
image and output the voxels to a df3 file.
Mark
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This is non-uniform scaling and not possible in raytracing.
Note 1: Well, strictly theoretically speaking it _is_ possible, but it
would be prohibitively slow.
Note 2: AFAIK non-uniform scaling is not implemented in _any_ renderer.
In most scanline renderers there's an option to scale object seemingly
non-uniformly, but it's not true non-uniform scaling; it just moves the
vertices of the triangles. A true non-uniform scaling would bend the
triangles. In raytracing even this "hack" wouldn't help since objects have
no vertices, but are completely mathematical entities.
--
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):5;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/
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Ken wrote:
> Here is my little wish list - tee hee !
>
> 1.) displacement mapping
For those interested in online resources for displacement mapping -
http://www.computer.org/cga/cg1998/g2044abs.htm
http://www.education.siggraph.org/materials/HyperGraph/mapping/displace.htm
http://graphics.stanford.EDU/papers/displace/gamma-corrected/
--
Ken Tyler - 1300+ Povray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/
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Here is my short list that I haven't seen anything
about:
camera {
...
gel{ color_information, opacity_value }
|gel_map{filetype "FileName", opacity_value }
}
This would allow the application of many different
affects. i.e. filters, ghost images and such.
In my mind this would be even more useful than
camera {... normal{...}}
--
Mr. Art
"Often the appearance of reality is more important
than the reality of the appearance."
Bill DeWitt 2000
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