Althouth the Utopian Idea of defining
Objects via chemistry-based, scientific
properties like density, viscosity, termal
reaction etc would go way beyond
anything a normal User would achieve,
it is interesting. I mean, who would actually
go create the reflective sphere with a
checkered plane, using lead, different
sets of marble, and go look up their
proper values?

What you're actually proposing is something
like a world-simulation, which should take
all known physical behaviours into account.
Problem with that is, that there are sometimes
quiet a diversity of approaches on how to
model and accurately put things into values.
Just take the different color-models,
RGB, which POV-Ray uses, is only one, and
there are several out there which may be of
better use for certain tasks.

I think a less Utopian Approach would be to
model different but specialized simulations. E.g.
one for fire, another for liquids, mass-particle
effects, with and without particle-interaction,
lighting models...
Once a basic setup is chosen (like: what of a
lightray is saved and handed down the recursive
tree: direction, reflection-points, intensity, color,
etc?), Plug-Ins should make use of different
properties and enhance/replace them. As for
simulations themselves (heat, for example), the
scene has to be preparsed somehow (at least
I'd expect that, using voxels or such), and then
the heat-simulation would run by itself. Introducing
a cold liquid? The liquid simulation takes care of
"being liquid", but the the heat-simulation reads
where the liquid is going and simulates heat-
properties for it. Combining both would make
it more difficult to properly set things up.

Just take my LSSM, the Liquid-Surface-Simulation-
Macros, as an example. They're only of use for
areas where the water is in an enclosed space, like
a pond, a swimming pool, or such. They create
near-realistic effects for waves. Aside of that, they
can't be used to simulate a burst of water into
a tunnel. Its just the surface. IMHO, taking care
of small parts, and combining them in the end, is
better, than having a huge, combined simulation,
where certain parts may be really redundant.


-- 
Tim Nikias v2.0
Homepage: http://www.digitaltwilight.de/no_lights
Email: no_lights (@) digitaltwilight.de


> >You might want to take a look at "Mechsim".
> >Creating an inbuilt physical simulation algorithm
> >with other techniques than that seems to me
> >quite impossible.
> >
> >The problem with scripting them into the core
> >of POV-Ray is that most of the time, several
> >approaches exist, and they might be quiet
> >contradictory in setting them up. AFAIK,
> >POV-Ray 4 should have better support
> >for plug-ins.
>
> Mechsim is certainly a great piece of code,
> and I have had a brief look at it, although
> I haven't used it in any of my own projects
> as of yet. But what I have in mind goes far
> beyond just basic mechanics simulation. For
> instance, consider the differece in lights
> and rendering between POV-Ray and Radiance:
> whereas POV simply uses a color float to
> specify the intensity and hue of a light
> source, Radiance takes a different approach,
> specifying the lights in a more scientific
> way. I imagine that such an approach could
> be taken a lot further, though. For instance:
> working with solid volumes (in the simulation,
> of course - it would be pointless in the actual
> rendering) rather than surface-based objects
> with insides and outsides; specifying materials
> in terms of elements and their characteristics,
> such as density, surface properties and so on,
> thus incorporating pigment, normal and media
> statements into a single grammar based in
> chemistry and - ultimately, but still far out
> of reach - particle physics; define groups of
> objects as "organisms", interacting according
> to kinematics, evolutionary algorithms, etc.
>
> Even if it was possible, it probably wouldn't
> be worthwile to incorporating such a diverse
> set of functions into the core of POV-Ray, and
> better support for plugins is always a good
> thing, of course. But adapting the program to
> scientific definitions and terminology in more
> respects than just the optical is a prerequisite
> for making the plugin system coherent from a
> conceptual viewpoint.
>
> (You should consider all of this as musings
> of a speculative mind with heavy utopian
> leanings, thinking beyond all restraints of
> actual computing power - I run POV on a puny
> 32 Mb RAM! My interest lies primarily in the
> discussion: the potential of simulation, not
> the actual state of affairs.)
>


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