After much pondering, I have developed a suite of macros for working
with triangle meshes.  One of these macros will take a mesh of triangles
and calculate the smoothing normals required.  Another will perturb the
vertices of the mesh, making it rougher-looking.

However, the macro of interest is the divider, which takes a rough mesh
of large triangles and replaces it with a mesh of smaller triangles that
give a more curved appearance.  This process can be repeated, yielding
a fine mesh of triangles that simulate a large variety of curved
surfaces.  Its primary purpose is to allow a user to create a smooth
organic shape, containing many triangles, by defining a rougher mesh of
far fewer triangles, and refining that in an automated way.

The Subdivision Surface Suite (SSS) can be found at:

  http://users.erols.com/vansickl/sss.htm

Regards,
John
-- 
ICQ: 46085459

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John VanSickle wrote:
> 
> After much pondering, I have developed a suite of macros for working
> with triangle meshes.  One of these macros will take a mesh of triangles
> and calculate the smoothing normals required.  Another will perturb the
> vertices of the mesh, making it rougher-looking.
> 
> However, the macro of interest is the divider, which takes a rough mesh
> of large triangles and replaces it with a mesh of smaller triangles that
> give a more curved appearance.  This process can be repeated, yielding
> a fine mesh of triangles that simulate a large variety of curved
> surfaces.  Its primary purpose is to allow a user to create a smooth
> organic shape, containing many triangles, by defining a rougher mesh of
> far fewer triangles, and refining that in an automated way.
> 
> The Subdivision Surface Suite (SSS) can be found at:
> 
>   http://users.erols.com/vansickl/sss.htm
> 
> Regards,
> John
> --
> ICQ: 46085459

I can only say Wow to this. If this works as advertized this will be a very
powerfull addition to the toolbox of mesh users everywhere. I'm impressed
John and thank you for the early XMAS present !!!

-- 
Ken Tyler

See my 850+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html

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Excellent idea!  MAX (yes sorry to say the forbidden word) has a plugin that
does a similar thing and I use it for the same reasons.

For anyone that wants to give it a go, try making a mesh that is like a
4-sided tube making a continuous knot.  (get what I mean?)  Then run it
through SSS and you should get a rather cool shape :)

I'm sure SSS will be a widely used Macro in this newsgroup from now on :)  I
look forward to some organic images in p.b.i 8)

--
Lance.


---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone
For a totally different experience, visit my Chroma Key Website:
Colorblind - http://listen.to/colorblind

P.S.  I finally have some more time now to get to these NGs, so you'll hear
a lot more of my usual dribble again.  ;)

John VanSickle wrote in message <37C84FE4.2C6A78C8@erols.com>...
>After much pondering, I have developed a suite of macros for working
>with triangle meshes.  One of these macros will take a mesh of triangles
>and calculate the smoothing normals required.  Another will perturb the
>vertices of the mesh, making it rougher-looking.
>
>However, the macro of interest is the divider, which takes a rough mesh
>of large triangles and replaces it with a mesh of smaller triangles that
>give a more curved appearance.  This process can be repeated, yielding
>a fine mesh of triangles that simulate a large variety of curved
>surfaces.  Its primary purpose is to allow a user to create a smooth
>organic shape, containing many triangles, by defining a rougher mesh of
>far fewer triangles, and refining that in an automated way.
>
>The Subdivision Surface Suite (SSS) can be found at:
>
>  http://users.erols.com/vansickl/sss.htm
>
>Regards,
>John
>--
>ICQ: 46085459

Post a reply to this message

Lance Birch wrote:
> 
> Excellent idea!  MAX (yes sorry to say the forbidden word) has a plugin that
> does a similar thing and I use it for the same reasons.

  It has surprised me for years now that with all of the features available
in Pov modelling programs not one of then that I have evaluated has this
feature. AutoCad 14 has an internal sub division ability (factres command)
for rendering meshs but has no ability to export them this way.

> P.S.  I finally have some more time now to get to these NGs, so you'll hear
> a lot more of my usual dribble again.  ;)

Good things comes to thems that waits I supposed. (Good grammer eh !)

-- 
Ken Tyler

See my 850+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html

Post a reply to this message

Very true, it seems that open source (kinda) programming works best and gets
the good features in quickly.  I guess Linux is a good example of that.

Luckily MAX comes with a lot of plug-ins (MeshSmooth as it's called, being
one of them) that are for mesh manipulation, but also work on patches, NURBS
(well not MeshSmooth because the meshes are handled internally in that
case), etc etc.

A feature that someone might consider making a macro for is an FFD (Free
Form Deformation) box.  The basic idea is that it builds an imaginary box of
verticies around an object and then as you move the vecticies it deforms the
object it's attached to.  What do you think, possible with POV-Ray?
(judging on all the cool mesh warps I've seen it should be)

If anyone's interested in making such a macro, here are the values that FFD
boxes use:

Falloff:  Adjusts the falloff of the effect of each vertex.  When 0, the
effect of each vertex is continuous (so distance doesn't matter).

Tension/Continuity:  Adjusts the tension and continuity of the deformation
splines (like the tension and continuity of a NURBS)

And of course the other standard ones you'd expect like number of divisions
on X, Y and Z.

*back to programming CGI*

--
Lance.


---
For the latest 3D Studio MAX plug-ins, images and much more, go to:
The Zone - http://come.to/the.zone
For a totally different experience, visit my Chroma Key Website:
Colorblind - http://listen.to/colorblind
Ken wrote in message <37C8C65D.B9778F5D@pacbell.net>...
>
>
>Lance Birch wrote:
>>
>> Excellent idea!  MAX (yes sorry to say the forbidden word) has a plugin
that
>> does a similar thing and I use it for the same reasons.
>
>  It has surprised me for years now that with all of the features available
>in Pov modelling programs not one of then that I have evaluated has this
>feature. AutoCad 14 has an internal sub division ability (factres command)
>for rendering meshs but has no ability to export them this way.
>
>> P.S.  I finally have some more time now to get to these NGs, so you'll
hear
>> a lot more of my usual dribble again.  ;)
>
>Good things comes to thems that waits I supposed. (Good grammer eh !)
>
>--
>Ken Tyler
>
>See my 850+ Povray and 3D Rendering and Raytracing Links at:
>http://home.pacbell.net/tylereng/index.html

Post a reply to this message

Lance Birch wrote:
> 
> Very true, it seems that open source (kinda) programming works best and gets
> the good features in quickly.  I guess Linux is a good example of that.
> 
> Luckily MAX comes with a lot of plug-ins (MeshSmooth as it's called, being
> one of them) that are for mesh manipulation, but also work on patches, NURBS
> (well not MeshSmooth because the meshes are handled internally in that
> case), etc etc.
> 
> A feature that someone might consider making a macro for is an FFD (Free
> Form Deformation) box.  The basic idea is that it builds an imaginary box of
> verticies around an object and then as you move the vecticies it deforms the
> object it's attached to.  What do you think, possible with POV-Ray?
> (judging on all the cool mesh warps I've seen it should be)

> --
> Lance.

Colefax has written a mesh deformation macro utility though I haven't explored
it's possibilities yet. Another tool worth looking at external to Pov is one
called Elasticity and has some powerful features once you go through the learning
curve of using the program.

Elasticity:
http://www.flash.net/~drsledge/manual/manual.htm

-- 
Ken Tyler

See my 850+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html

Post a reply to this message

John VanSickle wrote:
> 
> After much pondering, I have developed a suite of macros for working
> with triangle meshes.  One of these macros will take a mesh of triangles
> and calculate the smoothing normals required.  Another will perturb the
> vertices of the mesh, making it rougher-looking.
> 
> However, the macro of interest is the divider, which takes a rough mesh
> of large triangles and replaces it with a mesh of smaller triangles that
> give a more curved appearance.  This process can be repeated, yielding
> a fine mesh of triangles that simulate a large variety of curved
> surfaces.  Its primary purpose is to allow a user to create a smooth
> organic shape, containing many triangles, by defining a rougher mesh of
> far fewer triangles, and refining that in an automated way.
> 
> The Subdivision Surface Suite (SSS) can be found at:
> 
>   http://users.erols.com/vansickl/sss.htm
> 
> Regards,
> John
> --
> ICQ: 46085459

 One question John - Will your macros read in a file containing a triangle
mesh or is it currently resticted to meshes that are generated internaly
using functions for their creation ? If it is the latter would it be possible
to extend it's capabilities to indlude reading existing meshes ?

-- 
Ken Tyler

See my 850+ Povray and 3D Rendering and Raytracing Links at:
http://home.pacbell.net/tylereng/index.html

Post a reply to this message

Ken wrote:
> 
>  One question John - Will your macros read in a file containing a
> triangle mesh or is it currently resticted to meshes that are
> generated internaly using functions for their creation ? If it is the
> latter would it be possible to extend its capabilities to include
> reading existing meshes?

One of the issues I had to deal with is the inability of macro code to
erase and re-declare arrays that are passed to it as arguments.  The
array can be accessed, and its elements altered, but the dimensions, and
the size of each dimension, cannot be altered within the macro.

For instance, consider the following macro:

#macro ResizeArray(MyArray)
  #local Size=dimension_size(MyArray,1)
  #undef MyArray
  #declare MyArray=array[Size*2]
#end

An array that is passed to this macro will not be affected by the macro
whatsoever; what appears to happen is that POV-Ray forgets that MyArray
was an argument passed to the macro, and consequently a global array
with the name "MyArray" is created.  I haven't fully tested this out,
but one thing is for certain:  If you pass an array to a macro, that
macro cannot resize the array.

This is a problem because the divider code (which is the whole reason I
wrote the SSS to begin with) has to resize the arrays for each
iteration, for the simple reason that the number of triangles quadruples
with each execution of the division process.

For this reason, the SSS uses three globally-declared arrays, and the
names of these arrays must be Points, Edges, and Triangles; so if you
are going to use the SSS, you have to treat these labels as reserved
keywords, for all intents and purposes.

Another issue that has to be dealt with involves the vertices in the
mesh.  Consider the following mesh:

mesh {
  triangle { <1,0,0>,<1,2,0>,<1,1,2> }
  triangle { <1,1,0>,<1,2,0>,<2,2,0> }

...

}

These two triangles each have a corner at <1,2,0>.  Are the two
triangles supposed to be connected (ie, form a surface together), or
not?  In order to resolve this ambiguity, the code would have to know
what the user wanted, and in this case, there's not enough info to make
the call; the user needs to be more specific.

In order to get something subdivided, all you have to do is to define
two arrays:

  Points[PointCount] is an array of vectors representing the vertices of
the mesh.
  Triangles[TriangleCount][3] is an array of indices to the vertices of
the mesh.  Points[Triangle[n][0]] is the first vertex of triangle n,
Points[Triangle[n][1]] is the second vertex of triangle n, and
Points[Triangle[n][2]] is the third vertex of triangle n.

  In this way the ambiguity is resolved; if the point shared by two
triangles is meant to link them together, then both indices can refer to
the exact same member of Points[].  If they are supposed to go their
separate ways, then the indices should point to different elements,
which will have the same starting value.

  Now the subidivider needs a lot more info that I have specified here,
but there is a macro in the SSS that will generate this info, making it
unnecessary for the user to do so.

  So basically, your only real problem is to get the mesh data into the
two arrays Points[] and Triangles[][].  Anything that accomplishes that
will work just fine.

Regards,
John
-- 
ICQ: 46085459

Post a reply to this message

Ken wrote:
> 
> Colefax has written a mesh deformation macro utility though I haven't
> explored it's possibilities yet. Another tool worth looking at
> external to Pov is one called Elasticity and has some powerful
> features once you go through the learning curve of using the program.

One extra feature that I've already added to the SSS is a RoughenMesh
macro.  It perturbs the vertices of the mesh, thereby roughening it.
Put together with the right starting object, it makes rocks that are
just as good as the one my rock making .inc file kicks out, although
since the rock amker is a specialized script, it goes much faster on
what it does.

I'm already considering a macro to bend objects using a spline; if any
of you have seen the characters in the VeggieTales videos, and the way
they wiggle as they dance, you have some idea what I'm talking about.

The SSS relies on having the vertices and triangles in a set of arrays,
where they can be manipulated.  Consequently, whole boatloads of macros
can be written to do all manner of cool and obscene things to the mesh.
I'm sure that Chris' mesh stuff can easily be adapted to what I've got
in the SSS (and vice versa).

When the POV-Team gets around to adding UV support to POV, I will add
it to the SSS.  It will be a very simple addition to the code.

The RAM's the limit!

-- 
ICQ: 46085459

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Couldn't these macros be used with the PCM format?
  You could convert an ordinary mesh to PCM format with the triangle
compressor program, then read it to arrays with Colefax's PCM macro and
then use these macros.
  Have you considered asking Colefax if you two could work together in
a "superset" of mesh handling macros?

-- 
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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