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Alain wrote:
> There is a way, it's called "sandboxing". The process runs in a limited,
> closed, virtual machine and only have access to what YOU want it to see.

So, you propose that every time POV code loads an external program, you
launch a full-scale virtual machine? Are we going to license something
from VMware? Are you going to ask people to buy extra licenses from
Microsoft for the copies of the operating system running inside the VM?
(Jeez, I'm starting to sound like Warp.)

Sandboxing is great for your language's own scripts/bytecode, but is
less than helpful for _external_ libraries and arbitrary programs, which
is what we were talking about.

- --
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu

You know you've been raytracing too long when you have gone full circle
and find your self writing a scene that contains only a shiny sphere
hovering over a green and yellow checkered plane.
    -- Ken Tyler
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andrel wrote:
> It could also make the POV community diverge in groups with different sets
> of libraries. E.g. because some libraries are only available for a
> subset of OSes.

If that were the only problem, the extra flexibility would be well worth it.

This is one of those things that I would only expect 10% of the userbase
to even touch--if lots of people wind up needing it, it's because we
screwed something up.

Besides, we already have that showing up with people using modelers and
such. Remember that Pose-ray is Windows-only?

I'd say make as much as you can work inside of Pov (hence the argument
for a much expanded SDL that does things that people now use external
programs for), and then get out of the way of everyone that we can't
directly support.

Unless of course you want to include every obscure scientific
visualization library into Pov. ;-)

- --
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu

You know you've been raytracing too long when you spent the whole of
Titanic wishing the actors would get out of the way.
    -- Dylan Beattie
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Nicolas Alvarez wrote:
> Maybe we need something more POV-Ray specific, but I thought I should bring
> this up anyway... Have you heard of the Parrot bytecode[1]?

I haven't, but it looks very interesting.

- --
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu

You know you've been raytracing too long when you know the teapot bezier
patches by heart.
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On Sun, 30 Sep 2007 15:43:13 -0700, William Tracy wrote:

> If that were the only problem, the extra flexibility would be well worth
> it.

Only so far as the features one wants are in the OS that one is using.  
If you've used any OS other than Windows in the last 10 years, you've 
come to expect that full functionality may not be available in the OS of 
your choice.

Purposefully designing a program so that this can happen is a bad idea.  
If you pop over to the povray.unix group, you can see that some are 
already unhappy with the fact that POVRay on Windows has a "nice GUI" 
<spit - I prefer CLI myself>, but on *nix platforms, all you get is an 
"ugly CLI interface".

Now extend that to features in the language itself - that's a recipe for 
chaos, because the POVRay you use on *nix may not necessarily have the 
same functionality as the Windows version, and your scene files won't 
actually render because of missing functionality.  You end up with an SDL 
that is *not* portable.  Nonportability is BAD.

> Besides, we already have that showing up with people using modelers and
> such. Remember that Pose-ray is Windows-only?

That's a bit different than limiting the featureset of POVRay itself for 
users of some OSes.

Jim

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William Tracy <wtr### [at] calpolyedu> wrote:
> Nicolas Alvarez wrote:
> Have you heard of the Parrot bytecode[1]?
>
> I haven't, but it looks very interesting.

until you realize it's something, like Perl6 itself, that has been in the
works for about 6 years, without ever managing to get out of beta status.
In the hiatus, the python community came up with an innovative VM system
called PyPy and ruby increased its presence immensely.  And Lua too got a
lot of critical acclaim...

I was thinking... the next Povray supposedly is going to be GPL.  Would you
guys find it feasible to ship it together with GCC?  My point is:
JIT-compilation is still a relatively new area and there aren't sufficient
open-source implementations out there.  But traditional ahead-of-time
compilation is easily achieved.  If it was possible for a povray SDL script
to be compiled before running, performance wouldn't be a problem any more.

then, I could even suggest getting a Scheme implementation like chicken to
be a possible SDL frontend... :)

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> Fa3ien <fab### [at] yourshoesskynetbe> wrote:
>> If the shaders are compiled on the fly before rendering (which is, IMMSMW,
>> what POV-Man did), could they really be slower than hard-coded ones ?
> 
>   It assumes that the shaders can be compiled and that the compiler will
> be able to optimize them in the same way is the C++ compiler optimizes the
> current algorithms written in C++.

The most fundamental (and time-consuming) algorithms could be hard-coded
(ior, fractal noise, turbulence, whatever...) to gain the most speed.

And if the shader language is, in fact, an existing language, like C or Ruby,
or any smart choice, making use of POV-Ray-specific classes, efficient
compilation shouldn't be a problem (I think).

Fabien.

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Fa3ien <fab### [at] yourshoesskynetbe> wrote:
> And if the shader language is, in fact, an existing language, like C or Ruby,
> or any smart choice, making use of POV-Ray-specific classes, efficient
> compilation shouldn't be a problem (I think).

  There's a difference between something being inside the core C++ codebase,
and something JIT-compiled at runtime.

  Modern C++ compilers are quite good at optimizing, and it would be quite
hard for the JIT-compiler of any given scripting language to match that
level of optimization.

  Even if some JIT-compiler of some scripting language would achieve the
same speeds, the C++ compiler still has some advantages, such as being
able to inline certain functions for added speed (which naturally cannot
be done with JIT-compiled functions because they are unknown at the core
code compilation stage). Not that this matters a whole lot, but still.

-- 
                                                          - Warp

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Warp <war### [at] tagpovrayorg> wrote:
> Fa3ien <fab### [at] yourshoesskynetbe> wrote:
> > And if the shader language is, in fact, an existing language, like C or Ruby,
> > or any smart choice, making use of POV-Ray-specific classes, efficient
> > compilation shouldn't be a problem (I think).
>
>   There's a difference between something being inside the core C++ codebase,
> and something JIT-compiled at runtime.
>
>   Modern C++ compilers are quite good at optimizing, and it would be quite
> hard for the JIT-compiler of any given scripting language to match that
> level of optimization.
>
>   Even if some JIT-compiler of some scripting language would achieve the
> same speeds, the C++ compiler still has some advantages, such as being
> able to inline certain functions for added speed (which naturally cannot
> be done with JIT-compiled functions because they are unknown at the core
> code compilation stage). Not that this matters a whole lot, but still.
>
> --
>                                                           - Warp

I agree with Warp, with the following remarks:

-) We do not need that much speed for parsing, and if this allows us to meet
our requirements (object-orientedness and object-oriented notation, modules,
user-defined classes & methods, addons & new features,  user-definable
stuff, etc ...), we can sacrify some speed for it.

-) We need maximum computation power at render time. What are the quickest
langages for heavy computations? Basically, C++ is quick and very popular
among programmers (hackers or in industry) and benefits a lot of stuff.
FORTRAN (yes, I dared!) is also quick and takes better advantage of
vectorized computations and of processor pipelines, specialized in maths,
still very used in the industry yet much less popular, and benefits also a
lot of stuff.

-) What are the current langages supporting JIT? What are their
performances?

-) What are the langages which are best cross-platform and OS-independent?

Maybe we can make a round and see what we have at our disposal that is
likely to satisfy us for what we want.


    Bruno

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nemesis wrote:
> until you realize it's something, like Perl6 itself, that has been in the
> works for about 6 years, without ever managing to get out of beta status.

Ah. Okay, then. :-)

> I was thinking... the next Povray supposedly is going to be GPL.  Would you
> guys find it feasible to ship it together with GCC?  My point is:
> JIT-compilation is still a relatively new area and there aren't sufficient
> open-source implementations out there.  But traditional ahead-of-time
> compilation is easily achieved.  If it was possible for a povray SDL script
> to be compiled before running, performance wouldn't be a problem any more.

I really can't say how SDL would take to being compiled; I can say that
GCC is going to be a little bit of overkill for our needs. ;-)

Writing a new GCC frontend for SDL would be a big project in itself.

That said, GCC already supports a huge set of processor architectures. I
would not look forward to having to support a custom JIT compiler on
every conceivable processor, and I would not like to see POV stop
working on machines that are currently supported, either.

> then, I could even suggest getting a Scheme implementation like chicken to
> be a possible SDL frontend... :)

If you want to get yourself lynched, sure... ;-)

- --
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu

You know you've been raytracing too long when you consider 2D art that
of fools.
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Bruno Cabasson wrote:
> -) What are the current langages supporting JIT? What are their
> performances?

How about the Java runtime? Sun has already opened up the parts that
we'd actually need. (We have no use for the Java class libraries, and
once you strip those out the runtime binaries are only a couple
megabytes in size.)

> -) What are the langages which are best cross-platform and OS-independent?

Some of the existing Open Source JVMs support more processors than Sun's
OpenJDK; at the same time, Sun's implementation seems to be better
optimized on those platforms that are supported.

- --
William Tracy
afi### [at] gmailcom -- wtr### [at] calpolyedu

Penelope20k <pen### [at] caramailfr> wrote:
> > t'es la o boulot ... avec un cle USB?
  Yeah.
    -- Warp
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