POV-Ray : Newsgroups : povray.programming : Re: Can the trace() function be used to generate a mesh from an isosurface? Server Time
23 Dec 2024 11:17:54 EST (-0500)
  Re: Can the trace() function be used to generate a mesh from an isosurface? (Message 1 to 6 of 6)  
From: Christopher James Huff
Subject: Re: Can the trace() function be used to generate a mesh from an isosurface?
Date: 7 Nov 2002 21:30:43
Message: <chrishuff-F3DBBA.21304407112002@netplex.aussie.org>
In article <web.3dcb1deecf5e17f77748f6790@news.povray.org>,
 "normdoering" <nor### [at] yahoocom> wrote:

> I'm thinking that instead of the HF_ macros in shapes.inc that the trace
> function might be used to write a macro to generate a mesh file from an
> isosurface... Will this work?

There was a "triangle scanner" include file a while ago that did this, I 
think it was written for MegaPOV. The method it used didn't work very 
well, it was mainly only useful for a cheap preview.
It would theoretically be possible to duplicate the tessellation patch 
in POV-Script using trace(). It'd be a lot slower, and wouldn't have any 
advantages over the patch.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/


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From: Christopher James Huff
Subject: Re: Can the trace() function be used to generate a mesh from an isosurface?
Date: 7 Nov 2002 23:58:03
Message: <chrishuff-BE755D.23580107112002@netplex.aussie.org>
In article <web.3dcb24884533dc187748f6790@news.povray.org>,
 "normdoering" <nor### [at] yahoocom> wrote:

> What was the problem? Was the macro badly written?

No, the algorithm just didn't work very well. I think it used a kind of 
height field approach, maybe multiple height fields, making it 
impossible to represent many kinds of geometry.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/


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From: Warp
Subject: Re: Can the trace() function be used to generate a mesh from an isosurface?
Date: 8 Nov 2002 10:08:40
Message: <3dcbd378@news.povray.org>
Christopher James Huff <chr### [at] maccom> wrote:
> It would theoretically be possible to duplicate the tessellation patch 
> in POV-Script using trace(). It'd be a lot slower, and wouldn't have any 
> advantages over the patch.

  Actually the patch uses internally trace() to get the intersection points
with the surface (or at least the patch which I made does). :)

  In fact, I first made the tesselation with pov-SDL with the exact same
principles as the patch itself, but it was really, really slow, which was
the reason I decided to make it as a patch.

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -


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From: Christopher James Huff
Subject: Re: Can the trace() function be used to generate a mesh from an isosurface?
Date: 8 Nov 2002 12:10:27
Message: <chrishuff-33B5ED.12101808112002@netplex.aussie.org>
In article <3dcbd378@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

>   Actually the patch uses internally trace() to get the intersection points
> with the surface (or at least the patch which I made does). :)

Well, it uses the functions that the trace() POV-SDL function uses (the 
intersection methods accessed through the Intersect() macro). The 
Trace() function in the source code does something else, and there is no 
trace(). I know you know this, I'm just clearing it up for others.


>   In fact, I first made the tesselation with pov-SDL with the exact same
> principles as the patch itself, but it was really, really slow, which was
> the reason I decided to make it as a patch.

Hmm, sounds interesting...did you ever release the POV version? It might 
be useable on a more modern machine.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/


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From: Warp
Subject: Re: Can the trace() function be used to generate a mesh from an isosurface?
Date: 8 Nov 2002 15:50:18
Message: <3dcc238a@news.povray.org>
Christopher James Huff <chr### [at] maccom> wrote:
> Hmm, sounds interesting...did you ever release the POV version? It might 
> be useable on a more modern machine.

  Nope, and I can't find it anymore. I don't know what I did with it...

-- 
#macro M(A,N,D,L)plane{-z,-9pigment{mandel L*9translate N color_map{[0rgb x]
[1rgb 9]}scale<D,D*3D>*1e3}rotate y*A*8}#end M(-3<1.206434.28623>70,7)M(
-1<.7438.1795>1,20)M(1<.77595.13699>30,20)M(3<.75923.07145>80,99)// - Warp -


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From: Christopher James Huff
Subject: Re: Can the trace() function be used to generate a mesh from an isosurface?
Date: 8 Nov 2002 22:30:21
Message: <chrishuff-3C1EF4.22301308112002@netplex.aussie.org>
In article <3dcc238a@news.povray.org>, Warp <war### [at] tagpovrayorg> 
wrote:

> > Hmm, sounds interesting...did you ever release the POV version? It might 
> > be useable on a more modern machine.
>   Nope, and I can't find it anymore. I don't know what I did with it...

That happened to my electrical schematics include...too bad.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/


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