John VanSickle has made an excellent suite to smoothen meshes. This is
nice but I wondered: wouldn't it be possible to incorporate this in the
POV engine itself? With a heightfield you can add the "smooth" keyword
and for meshes you can have smoothe triangles but I think it would be
really great if you could have a recursive smoothe like in John's
suit(e) ;) For that you would have to have another way to define a mesh.
The advantage of this would probably mainly be speed but also an easier
way to model all sorts of stuff (as John demonstrated with the tree
branche picture posted last week).
Is this a stupid idea?

Remco

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Remco de Korte wrote:
> 
> John VanSickle has made an excellent suite to smoothen meshes. This is
> nice but I wondered: wouldn't it be possible to incorporate this in the
> POV engine itself? With a heightfield you can add the "smooth" keyword
> and for meshes you can have smoothe triangles but I think it would be
> really great if you could have a recursive smoothe like in John's
> suit(e) ;) For that you would have to have another way to define a mesh.
> The advantage of this would probably mainly be speed but also an easier
> way to model all sorts of stuff (as John demonstrated with the tree
> branche picture posted last week).
> Is this a stupid idea?
> 
> Remco

I would say that it is not a bad idea. I have several sites listed
in the links collection that talk about subdivision surfaces and a
couple offers some fairly fast algorithms for this type of process.
There will be an obvious perfomance difference over John's utility
but it will still be a costly process especialy with high polygon
counts.

-- 
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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On Tue, 18 Jan 2000 20:21:06 +0100, Remco de Korte
<rem### [at] xs4allnl> wrote:

> For that you would have to have another way to define a mesh.

Or just add two keywords to the mesh syntax, like:

subdivide <Iterations>
autosmooth <Angle>


Peter Popov
pet### [at] usanet
ICQ: 15002700

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Ken wrote:
> 
> Remco de Korte wrote:
> >
> > John VanSickle has made an excellent suite to smoothen meshes. This
> is
> > nice but I wondered: wouldn't it be possible to incorporate this in
> the
> > POV engine itself? With a heightfield you can add the "smooth"
> keyword
> > and for meshes you can have smoothe triangles but I think it would
> be
> > really great if you could have a recursive smoothe like in John's
> > suit(e) ;) For that you would have to have another way to define a
> mesh.
> > The advantage of this would probably mainly be speed but also an
> easier
> > way to model all sorts of stuff (as John demonstrated with the tree
> > branche picture posted last week).
> > Is this a stupid idea?
> >
> > Remco
> 
> I would say that it is not a bad idea. I have several sites listed
> in the links collection that talk about subdivision surfaces and a
> couple offers some fairly fast algorithms for this type of process.
> There will be an obvious perfomance difference over John's utility
> but it will still be a costly process especialy with high polygon
> counts.
> 
> --
> Ken Tyler -  1300+ Povray, Graphics, 3D Rendering, and Raytracing
> Links:
> http://home.pacbell.net/tylereng/index.html
> http://www.povray.org/links/

There is an other advantage: memory. Subdividing a mesh with a POV-macro
results in a large amount of triangles which need a lot of memory. The
amount of memory needed gets ugly very quickly. With a different way of
allocating memory (as it is now a triangle takes far more memory then I
think is needed) you'll be able to use a deeper recursion level. 

Remco

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Peter Popov wrote:
> 
> On Tue, 18 Jan 2000 20:21:06 +0100, Remco de Korte
> <rem### [at] xs4allnl> wrote:
> 
> > For that you would have to have another way to define a mesh.
> 
> Or just add two keywords to the mesh syntax, like:
> 
> subdivide <Iterations>
> autosmooth <Angle>
> 
I think the subdivision routine needs the info ordered in another way
then as it is in a simple mesh: one point-list with the coordinates of
all the used points (which eliminated duplicate points) and a
triangle-list with for each triangle three pointers to the point-list.
Or something like that...

Remco

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Remco de Korte <rem### [at] xs4allnl> wrote:
: I think the subdivision routine needs the info ordered in another way
: then as it is in a simple mesh: one point-list with the coordinates of
: all the used points (which eliminated duplicate points) and a
: triangle-list with for each triangle three pointers to the point-list.

  AFAIK povray internally converts meshes to this format.

  And AFAIK the mesh2 format of megapov is just a kind of "shortcut" to this
format.

-- 
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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Peter Popov wrote:
> 
> On Tue, 18 Jan 2000 20:21:06 +0100, Remco de Korte
> <rem### [at] xs4allnl> wrote:
> 
> > For that you would have to have another way to define a mesh.
> 
> Or just add two keywords to the mesh syntax, like:
> 
> subdivide <Iterations>
> autosmooth <Angle>

A straight interation count, applied to the whole mesh, will work
just fine.  However, with the Loop surface method, smoothing everything
sharper than a certain angle can only be done by subdividng the whole
mesh until every angle is under threshold.

Regards,
John
-- 
ICQ: 46085459

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Nieminen Juha <war### [at] punarastascstutfi> wrote ...
> Remco de Korte <rem### [at] xs4allnl> wrote:
> : I think the subdivision routine needs the info ordered in another way
> : then as it is in a simple mesh: one point-list with the coordinates of
> : all the used points (which eliminated duplicate points) and a
> : triangle-list with for each triangle three pointers to the point-list.
>
>   AFAIK povray internally converts meshes to this format.

True.

>   And AFAIK the mesh2 format of megapov is just a kind of "shortcut" to
this
> format.

True, mesh2 is exactly this format.

-Nathan

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Peter Popov <pet### [at] usanet> wrote...
>
> Or just add two keywords to the mesh syntax, like:
>
> subdivide <Iterations>
> autosmooth <Angle>

It is also very useful with subdivision surfaces to allow specific edges to
be defined as 'sharp', meaning that they are not smoothed.

-Nathan

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