"Chris Huff" wrote:
> You can apply non-linear transformations to isosurfaces by
> modifying their functions.

Deforming functions due to simple mathematical functions can be fine. But
the kinds of transformations I'm talking about are things like for example
animating a character. This can hardly be done by having the user modifying
functions.

> Bicubic patches, height fields, meshes, and other tesselated
> objects could also be deformed fairly easily without
> changing the rendering method very much, but you would have
> to make fairly major additions to the code.

But if it would be as powerful as I wish for, it would be a fairly major
feature.

So far character animation in POV-Ray has always been using robots, or if
organic objects were used, they were not UV-mapped, and if they were, they
were animated in another program and then exported to POV-Ray. I would like
to animate organic, UV-mapped characters in POV-Ray itself. The deformation
features I'm talking about would be an important part of making that
possible.

But is it worth it making such big changes to POV-Ray just to be able to
animate characters? I think yes. I believe good character animation is
considered the highest achievement in the 3d graphics industry. And besides,
the deformations I'm talking about would be useful for *many* other things
too.

> > I suggest that we begin to think of the possibilities of
> > implementing such functions.
>
> You're a little late...Wlodzimierz ABX Skiba has already
> been working on a deform patch, which apparently can work on
> all objects.

And that's great. But I believe the kind of features I
suggested hasn't been discussed.

> Also, Warp is working on a tesselation patch that could be
> used to do similar things.

Tessellation and deformation is not the same thing. Although it would indeed
make deform features even more useful.

> All of this was discussed, including the possibility of using
> warps.

Not well enough I think.

> > But more complicated ways of deforming may be useful. I have
> > thought of a feature that would deform objects by several
> > user-specified regular transforms, each weighted by a 3D
> > field in space.
> ...snip...

You snipped the most important part...

> I think it would be better to define deformations with a warp,
> and implement a new warp that does this. I think it would be
> a good idea to keep a single syntax for deforming both objects
> and textures.

Chris, that doesn't make sense. Textures and objects are entirely different
things and cannot be deformed in the same way. Allow me to explain.

AFAIK textures are deformed in a backward kind-of-way, while meshes are
deformed in a forward kind-of-way. That means that one piece of a texture
can be copied to several locations (think repeat warp). That is not possible
with meshes.

Meshes work the other way around. That means that several pieces of a mesh
can be moved to the same location (think of a mesh snake that bends and
bites its own tail). This is not possible with textures. Texture space can't
overlap itself.

Even if some texture warps can be used on objects too, they will not give
identical perpetuations on textures and meshes. But saying that *all*
deformations should work for both textures and objects is nonsense. That's
what my logic tells me anyway.

I would appreciate if you would reconsider my suggestions so we could maybe
have a more rewarding discussion about them.

Rune
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