> If triangles are ok, you could have a look at the Striscia macro.
> http://members.nbci.com/dvarrazzo/

As long as the "triangles" are not visible, but only a curved cylinder, cuz if
the triangles would be visible, I would simply use a 3d modeler and bingo... but
no, I want to use povray... would the smooth triangles do it?

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A bending transformation (which is a nonlinear transformation) is not
possible for mathematical and technical reasons (see
http://www.students.tut.fi/~warp/povVFAQ/languageVFAQ.html#bending).

  You have many choices:

  You can use a torus section for a bended cylinder. A bended cone is harder
(can't be done with existing primitives, at least not perfectly).

  You can make isosurfaces. All those objects should be possible with them,
but it will require quite a lot of math knowledge.

  You can make them with a mesh of smooth triangles. You still need some
math, but probably not as much as with isosurfaces.
  This solution is not as bad is it might sound. You can use LOTS of triangles
to make the shape (so that you don't get visible straight line segments in
the silhouette of the object) without the rendering slowing down (but of
course memory usage will increase).

  You can make them with bicubic patches. The result is exactly the same
as with the mesh of smooth triangles, but the advantage is that you can
more easily control the resolution of the mesh.
  The disadvantage is that you need more complicated math than with the mesh
(if it can be used as a reference, I myself know enough math to make the mesh
but not the bicubic patches for bended cylinders and cones).

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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I'd say make a script to generate triangle meshes, use isosurfaces (requires MegaPOV
from
nathan.kopp.com), or (for the cylinders only) a torical section; if you need math help
let
me know.

--
David Fontaine  <dav### [at] faricynet>  ICQ 55354965
My raytracing gallery:  http://davidf.faricy.net/

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> I'd say make a script to generate triangle meshes, use isosurfaces (requires MegaPOV
from
> nathan.kopp.com), or (for the cylinders only) a torical section; if you need math
help let
> me know.

Yes this is good, I would actually make a C++ program for this, as I usually
do...

But,  I forgot to say about interior...  it is being discussed in
povray.advanced-user and as I know a bunch of triangles togheter won't have a
proper interior... which will be important as soon as I get a curver cylinder,
this is my next step, I forgot to mention it...

I think the best way to do it is still to put a few cylinders togheter and curve
them myself...  the junction could be made with an intersection of the two
segments and the union of the two segments themselves, etc...

What do you think?

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| Simon Lemieux           | Website : http://www.666Mhz.net  |
| Email : Sin### [at] 666Mhznet | POV-Ray, OpenGL, C++ and more... |
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Simon Lemieux wrote:

> I think the best way to do it is still to put a few cylinders togheter and curve
> them myself...  the junction could be made with an intersection of the two
> segments and the union of the two segments themselves, etc...

You mean paste together cylinder sections? Tori section would have infinite resolution
and
render fast... and isosurfaces give you the ultimate control, you give it a function
and it
renders the implicit surface...

--
David Fontaine  <dav### [at] faricynet>  ICQ 55354965
My raytracing gallery:  http://davidf.faricy.net/

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> You mean paste together cylinder sections? Tori section would have infinite
resolution and
> render fast... and isosurfaces give you the ultimate control, you give it a function
and it
> renders the implicit surface...

Tori sections is a good idea, but what for a cone?  There I would need cone
sections...

But I've never used/read-about isosurface before, do they have interior?  Could
you send me a picture url that would describe this in a word?  And is it in the
manual of povray, or, where could I get more information about isosurface?

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| Simon Lemieux           | Website : http://www.666Mhz.net  |
| Email : Sin### [at] 666Mhznet | POV-Ray, OpenGL, C++ and more... |
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In article <39D### [at] yahoocom>, lem### [at] yahoocom wrote:

> Tori sections is a good idea, but what for a cone?  There I would 
> need cone sections...

To do that you would have to use isosurfaces...fortunately, the function 
to do that shape would be pretty simple and fast rendering, just vary 
the minor radius of a torus function with angle.


> But I've never used/read-about isosurface before, do they have interior?  

They are ordinary solid objects, so they can be used as media containers 
and work fine in CSG.


> Could you send me a picture url that would describe this in a word?

A picture? An isosurface can do nearly every primitive in POV-Ray, and 
many other shapes.
Basically, you supply an equation that gives a value based on xyz 
coordinates. The isosurface is the surface formed by all points where 
your function is equal to a certain threshold value.
There are several tutorials online, but I don't have the URLs handy for 
any of them right now...they would be on the links page at povray.org 
though.


> And is it in the manual of povray, or, where could I get more 
> information about isosurface?

They are not in the official version yet, but they are included in 
MegaPOV, an unofficial version.
http://nathan.kopp.com/patched.htm

-- 
Christopher James Huff
Personal: chr### [at] maccom, http://homepage.mac.com/chrishuff/
TAG: chr### [at] tagpovrayorg, http://tag.povray.org/

<><

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> > And is it in the manual of povray, or, where could I get more
> > information about isosurface?
> 
> They are not in the official version yet, but they are included in
> MegaPOV, an unofficial version.
> http://nathan.kopp.com/patched.htm

Oh... I see, I've heard Povray 4 will be released soon or has already been
released?  Will it contain the isosurfaces?  I'll check out for MegaPov...

Thanks

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| Simon Lemieux           | Website : http://www.666Mhz.net  |
| Email : Sin### [at] 666Mhznet | POV-Ray, OpenGL, C++ and more... |
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Simon Lemieux wrote:

> Oh... I see, I've heard Povray 4 will be released soon or has already been
> released?  Will it contain the isosurfaces?  I'll check out for MegaPov...

POV-Ray v3.5 will be released (relatively) soon and will offer
isosurfaces. POV-Ray v4.0 is a mere twinkle in the POV-Team's
eye at this point in time.

-- 
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/

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Chris Huff <chr### [at] maccom> wrote:
: An isosurface can do nearly every primitive in POV-Ray, and 
: many other shapes.

  Good that you said "nearly" because isosurfaces can't do _every_ primitive
in povray.

  Quiz: Which primitive or primitives it can't create at all?
        Which primitive or primitives it can create only partially?

-- 
main(i,_){for(_?--i,main(i+2,"FhhQHFIJD|FQTITFN]zRFHhhTBFHhhTBFysdB"[i]
):_;i&&_>1;printf("%s",_-70?_&1?"[]":" ":(_=0,"\n")),_/=2);} /*- Warp -*/

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