Peter Popov wrote:
> 
> [...]
> Using penalty functions (as you do) has the advantage that it is
> generally simpler to implement and faster to compute. The problem is
> that due to the infinite gradient of the penalty function (the
> function being 0 outside the object and non-zero inside), it is
> impossible to use higher-order integration methods.

I'm not totally sure about the terminology but i always thought the force
based apprach is what's commonly called penalty methods.  What Rune uses
is
the classical impact rules based 'reflecting the velocity at the surface'.

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 13 Aug. 2002 _____./\/^>_*_<^\/\.______

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Rune wrote:
> 
> > The possibility of people abusing this seems extremely
> > remote in the case of POV-Ray.
> 
> Still, there are people who both can and will pay for a license to use
> my files commercially, and I'd like to take that opportunity for *me* to
> make a few bucks on the work I have done. And I think it's only fair.

I don't think it will work.  Think about what you will actually be
selling: You sell the right to use a program to make money.  Do you know
any product that successfully followed such a concept?  The only example i
can think of are free versions of compilers (for example Delphi) that are
not allowed to be used for commercial purposes.  But this is quite
different because such free versions are also restricted otherwise (no
support, older version) and are always introduced after the main product,
mainly as an advertisement system.

Your include file can be seen as a program processing data: you put in the
parameters and get out the particle positions.  So you in fact restrict
the usage of the data processed by your program.  This is perfectly legal
of course but very uncommon.  Also note that this is quite different from
the example of Poser freebies Gilles gave - there it is about restricting
the usage of data (i.e. models).

> 
> > Also, *** requiring *** people to give you credit
> > is too much to ask.
> 
> Why? I think it's quite common tendency for free things on the net,
> isn't it?

Maybe it is but don't mix it up with the requirement of credit when
producing derivative work (like in the BSD licence).

Christoph

-- 
POV-Ray tutorials, IsoWood include,                 
TransSkin and more: http://www.tu-bs.de/~y0013390/  
Last updated 13 Aug. 2002 _____./\/^>_*_<^\/\.______

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On Mon, 21 Oct 2002 11:05:22 +0200, Christoph Hormann
<chr### [at] gmxde> wrote:

>I'm not totally sure about the terminology but i always thought the force
>based apprach is what's commonly called penalty methods.  What Rune uses
>is
>the classical impact rules based 'reflecting the velocity at the surface'.

Rune's approach is kinematic. A penalty function implies a dynamic
approach. However, the results are very similar.

Basically, a penalty function is such that it results in reversed
velocity in the next iteration. It always points normal to the surface
at the point of collision and it magnitude is such that the momentum
and kinetic energy of the particle are changed according to the laws
of (partially) elastic collision.


Peter Popov ICQ : 15002700
Personal e-mail : pet### [at] vipbg
TAG      e-mail : pet### [at] tagpovrayorg

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Rune wrote:
> I appreciate this discussion, so please don't hesitate to pursue your
> arguments further. It is not totally out of the question that I might
> make changes to some of the terms... :)

  If you are about to change them, do it now: the arguments can be most 
clear than as Gilles exposed it. 

  In my case, I can only say that I downloaded your files, then read the 
TOS, and inmediately deleted your files... and I really wanted to use them 
(excelent work, indeed!). 

  The (inexistant) TOS under wich I release ALL my images is not compatible 
with your conditions... :( 

-- 
Jaime Vives Piqueres

La Persistencia de la Ignorancia
http://www.ignorancia.org

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>   In my case, I can only say that I downloaded your files, then read the
> TOS, and inmediately deleted your files... and I really wanted to use them
> (excelent work, indeed!).

My reaction exactly. I'm afraid this isn't in the spirit of Pov which as Ken
has already said, "is kinda sad."

Mick

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Jaime Vives Piqueres wrote:
>   The (inexistant) TOS under wich I release ALL my
> images is not compatible with your conditions... :(

Which part(s) of the conditions?

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com (updated Oct 19)
POV-Ray Ring: http://webring.povray.co.uk

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Ken wrote:
> It is almost like a slap in the face of the entire
> POV-Ray community and came quite unexpectedly.

That's quite strange, because I've had the same terms of use for years,
for all my include files. I even asked once in povray.off-topic (quite a
while ago) what people thought of the terms I used, and I didn't at all
get as negative responses as I do now.

> Maybe I should place restrictions on the use of my
> links collection. If I were to charge a nominal fee
> for every link accessed it would really help
> supplement my meager income. Do you think anyone
> would mind?

If it was kept free for non-commercial use, I certainly wouldn't mind.

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com (updated Oct 19)
POV-Ray Ring: http://webring.povray.co.uk

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Christoph Hormann wrote:
> Rune wrote:
>> Still, there are people who both can and will
>> pay for a license to use my files commercially,
>> and I'd like to take that opportunity for *me*
>> to make a few bucks on the work I have done.
>> And I think it's only fair.
>
> I don't think it will work.  Think about what you
> will actually be selling: You sell the right to
> use a program to make money.

Sounds sensible to me.

> Do you know any product that successfully followed
> such a concept?

I don't know what products have *successfully* used that concept, but
there sure seems to be a lot of programs that use it.
<http://www.google.com/search?sourceid=navclient&q=%22non%2Dcommercial+u
se%22>
(I know that not *all* of these are programs.)

Oh, and I've sold some commercial licenses for my other include files in
the past, so that would count as a successful example too.

And I don't see how it's so different from for example a poser mesh,
that you pose and texture yourself and then put in your scene. In both
cases, it is something that you can place in your scene, and there are
some things given, and some things that can be customized by the user.

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com (updated Oct 19)
POV-Ray Ring: http://webring.povray.co.uk

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3db3368d@news.povray.org...
> It's a personal benefit. I have not given my files to the public domain,
> and I'd like to keep control of how and where they are distributed. That
> is not possible if people can distribute modified versions of my files
> as they please.

But people who don't put these sort of restrictions don't seem to suffer
from it. I certainly don't. So why the extra and unfriendly step ?

> Would you gain any profit from this? If yes, see above. If not, this
> might be a good situation to ask me for a special permission, since the
> situation is a bit special (commercial work where you don't get any
> profit yourself).

For me, while this type is reasoning makes sense at personal level ("I don't
want people to rip me off"), it is also an example of how things get out of
hand. If everyone acted like this, there would never have been a POV-Ray
community, and most people - including you and me - would never have been
acquainted with it.

Please, use your imagination and think hard about it : what if everyone was
doing that ? What sort of legalese hell would it be ?

> Still, there are people who both can and will pay for a license to use
> my files commercially, and I'd like to take that opportunity for *me* to
> make a few bucks on the work I have done. And I think it's only fair.

Come on... No one is making a living out of POV-Ray. We're spending money on
it. It cannot be used in the sort of professional environment that actually
brings money. Yes, there's the rare commissioned work, but selling posters
brings me, in average, a grand total of 15 Euros per image and per year. If
I'm using your macros in an image, how much do you want ? 1 Euro ? Sorry,
but it doesn't make much sense to depart from the tradition of exchange in
this community to get some pocket change. What sort of benefit is there in
it, for you and for everyone here ?

> As I've said, I can only appeal to people's honesty.

By requiring them to do it you imply that they're dishonest by default. It's
like putting "Customers, we remind you that you must pay for what you buy"
signs in a shop.

> I'm not sure what you mean by "selling my skills rather than the product
> itself".

I mean that the real value of your work is not in your macros but in your
skills. Unless your macros can be used as Maya plug-ins, you won't make
significant money out of them. However, by voluntarily limiting their
diffusion, you hurt yourself because of the lack of exposure you need as
someone with real 3D skills. If I was to make a commercial picture with them
(one which would end in a book or a record cover), THAT would mean real
advertising for your talent as a programmer, because I would certainly
credit you. In the past years, 3 companies have sent me free software for me
to use them and to be frank I'm the one who got ripped off because I
certainly made them make money :-)

> > OK, what if Chris Colefax, or Jaime or I start doing
> > the same... Or the POV-Team itself ? Anyone here want
> > to see that ?
>
> We surely couldn't blame them.

And we would never had this community. One thing that is great about it is
that people don't spend their time bitching about money lost and gained, and
who cheated who over what.
I saw the Poser community evolve that way, and it's ugly, but at least Poser
is a commercial product and there are people actually making a living out of
Poser-related products, so it's partly justified. This not the case for
POV-Ray.

> > Also, *** requiring *** people to give you credit
> > is too much to ask.
>
> Why? I think it's quite common tendency for free things on the net,
> isn't it?

Yes it's a trend and I don't see the point in following it. For all I know
it's only justified because people try to imitate the big names, possibly to
make themselves seem bigger. "Hey, I put an EULA on my crappy Poser prop,
I'm the next Bill Gates now". It's an ego trip and funnily enough it was
noted that the few real merchants offering freebies don't do it out of
respect for their customers, paying ones or not.
Again, there's nothing to lose by not doing it, it's simply more polite and
friendly.

G.

--

**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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I've changed the terms a bit again.

Still not free for commercial use, but the requirement for credits is
changed to a request. And the terms now say nothing about making
modified versions of my files, as long as they are not distributed.
http://runevision.com/welcome/terms/terms.asp

Hope it's a bit better, though I realize that many will still not be
satisfied...

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com (updated Oct 19)
POV-Ray Ring: http://webring.povray.co.uk

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