"Dan P" <dan### [at] yahoocom> wrote in message
news:407f2150$1@news.povray.org...
> >> "Rafal 'Raf256' Maj" <spa### [at] raf256com> wrote in message
>
> <snip />
>
>  >>Too wash-out colors.
>
>
> Sun Tzu wrote:
>  >
> > I intentionaly made the colors 'pastel', but perhaps you're right that
it
> > would look better with more brilliant colors.  Fortunately I wrote out
the
> > xyz locations and gross sizes of the eggs to a txt file so I could try
> > different things without lengthy re-parse.
> >
> > I've attached a revised image with darker colors for your comment.  I'm
> > unsure of the newsgroup etiquette (if any) that may apply regarding
posting
> > of images in replies.  Let me know if this practice is contrary to some
such
> > rule.  Thanks.
>
>
> I actually liked the first one better :-) It had a more light feeling.
> Maybe more saturation?
>
> A quick note on etiquette: usually we post after a paragraph to match
> the natural order of reading (posting above is called "top posting". I
> took this particular post and reformatted; note that Rafal's response is
> first, then your response, and finally mine at the bottom. That way, the
> reader doesn't have to "scan up" the page. I also snipped out anything
> that wasn't relevant to the replies by using some sort of "snip"
indicator.
>
> This is, unfortunately, something we all tend to learn from tactless,
> frustrated newsgroup nazi losers who have nothing better to do. You're a
> lucky one to get me! :-)

I much prefer top posts actually.  (I'm just bottom posting now as a
courtesy to you because I now know you prefer it, hehe)  I find it very
frustrating when I've been keeping up with a thread to scroll all the way
down to the new stuff at the bottom every time.  I like to see the newest,
currently relevant text first, and if I'm not up to date with the thread I
can scroll down and read the history if I want to.  That is the way I've
always seen email done as well.  The current comments at the top and the
thread history below.

Of course if there is actually a consensus here regarding the 'correct' way
to do this I will conform.  :-)

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Sun Tzu wrote:
> LOL!   Yea, I believe that it is, but that wasn't my intent.
> 
> 
> "Jim Charter" <jrc### [at] msncom> wrote in message
> news:407ee97b$1@news.povray.org...
> 
>>Isn't that Spanish slang?

In Mexican slang, it does mean something :-)

It is sort of "a lot of courage" or "a lot of manly power"

"Huevos" means "balls", so you can imagine where the expression comes 
from...

Fernando.

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> I have no experience at all with collision avoidance methods and just did
> the first thing that came to mind.  Doubtless it is hideously inefficient.
> I just calculated the distance from each newly generated location to each
> of the previous ones...   I can already think of a couple of ways to
> improve on it.  I didn't even exit the loop as soon as a failure was
> detected and just continued on checking all the previous locations!  haha.
> If you have some information on different algorithms for this sort of
thing
> I'd be happy to see them.

Well, there are several ways to do this. The one you used is brute force,
just place and check. An advantage would have been stopping the comparisons
once it has been determined that the current position is invalid.

Another fast method (though I don't have the script for that right now) is
to use functions. Similiar to the approach of saving all positions and
checking those, you could use a function to keep track where the posititions
are. In this manner, all positions get added to that function via
redeclaration, and to check, you just have to do one call to the function.
But this is just a speed-enhancement, the method is essentially the same.

You could also divide the space in which you place the eggs into cubes.
Determine in which cube the new position is and only check that cube and the
neighbourig cubes. Thus you don't check with positions which are too far
away anyway.

Another method, which works in many cases, is just calculate a grid of
positions with enough distance to each other, and then randomize those
points slightly. If done correctly, the observer won't notice the underlying
pattern and it will seem random. There no checking with other positions
done, which is a major speed up.

That's about it. I think there are some more variations to these methods,
but essentially, that wraps it up, I guess.

Regards,
Tim

-- 
"Tim Nikias v2.0"
Homepage: <http://www.nolights.de>

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"Tim Nikias v2.0" <#macro timnikias (@) #local = "gmx.net" #end> wrote:

*snip*

> Another fast method (though I don't have the script for that right now) is
> to use functions. Similiar to the approach of saving all positions and
> checking those, you could use a function to keep track where the posititions
> are. In this manner, all positions get added to that function via
> redeclaration, and to check, you just have to do one call to the function.
> But this is just a speed-enhancement, the method is essentially the same.

I don't understand this at all.  I understand 'macros' in SDL (I think)and I
just looked at the POV documentation on functions, but don't see how one
can be used in this way.  If anyone can dig up a simple example I'd
appreciate it.

>
> You could also divide the space in which you place the eggs into cubes.
> Determine in which cube the new position is and only check that cube and the
> neighbourig cubes. Thus you don't check with positions which are too far
> away anyway.

Yea, I thought of this afterward too.  It just seemed more laborious to code
than I wanted to get into.  heh.

>
> Another method, which works in many cases, is just calculate a grid of
> positions with enough distance to each other, and then randomize those
> points slightly. If done correctly, the observer won't notice the underlying
> pattern and it will seem random. There no checking with other positions
> done, which is a major speed up.

I like this idea!  As you say, if the initial spacing and magnitude of
subsequent randomization are selected correctly, there is no need to check
anything.  Very nice.  Thanks.

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Among other things, Dave VanHorn wrote:

> Vaya con dios,  Go with god.
> Vaya con huevos, "go with eggs".



;)

-- 
light_source{9+9*x,1}camera{orthographic look_at(1-y)/4angle 30location
9/4-z*4}light_source{-9*z,1}union{box{.9-z.1+x clipped_by{plane{2+y-4*x
0}}}box{z-y-.1.1+z}box{-.1.1+x}box{.1z-.1}pigment{rgb<.8.2,1>}}//Jellby

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Among other things, Dan P wrote:

>>>>Isn't that Spanish slang?
>>>
>>>Not really slang, just "many eggs".
>>>
>> I believe 'huevos' is a commonly used slang expression for testicles, and
>> that Jim is referring to that usage.

Yes, while there could be some "slangish" meaning in the phrase, the words 
are most common, that's what I meant :)

> I thought that was cahones (sp?)!

If the Spanish speakers here will pardon the language, it's "cojones" 
("cajones" means drawers).

-- 
light_source{9+9*x,1}camera{orthographic look_at(1-y)/4angle 30location
9/4-z*4}light_source{-9*z,1}union{box{.9-z.1+x clipped_by{plane{2+y-4*x
0}}}box{z-y-.1.1+z}box{-.1.1+x}box{.1z-.1}pigment{rgb<.8.2,1>}}//Jellby

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Sun Tzu wrote:
> I find it very frustrating when I've been keeping
> up with a thread to scroll all the way down to the
> new stuff at the bottom every time.

That's when people quote way to much... Otherwise you shouldn't have to
scroll.

> That is the way I've always seen email done as well.
> The current comments at the top and the thread
> history below.

No, no! You're not supposed to include any history at all! Only the
parts strictly necessary should be included when you're replying
directly to them, and that should be above your reply. If the quoted
text is not necessary to get meaning out of your post, then just strip
it away altogether. :)

Take this post as an example. There are two statements of yours that I
replied to, so I first quoted the first one and replied to that one, and
then quoted the second one and replied to that one. My replies wouldn't
have made much sense if there were no quotes at all, yet I only quoted
very little text, so you don't have to scroll. :)

Rune
--
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com **updated Mar 9**
POV-Ray Ring: http://webring.povray.co.uk

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> I was inspired by Andrew C's Easter post so I decided to make some eggs.

*sits down*

Well, I _believe_ that's a first for this NG... someone inspired by ME! Heh.

> This is my first try at randomly placing a large number (3500) of objects
> with a rudimentary test to avoid intersecting objects.  It ran last night on
> a 2 GHz Pentium:  8 hours 45 minutes parse, 38 minutes trace.

Hmm... obviously something not quite right with the algorithm then... 
(as Tim already pointed out). The last one of His suggestions was the 
first thing that occurred to me.

(I once tried to do a system for randomly placing spheres so that they 
touch. That was pretty slow too - and still didn't look right. Mind you, 
what I really wanted was something gravitationally stable, which wasn't 
in my algorithm at all...)

Andrew @ home.

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Sun Tzu wrote:

> "Dan P" <dan### [at] yahoocom> wrote in message
> news:407f2150$1@news.povray.org...

<snip />

>>A quick note on etiquette: usually we post after a paragraph to match
>>the natural order of reading (posting above is called "top posting". I
>>took this particular post and reformatted; note that Rafal's response is
>>first, then your response, and finally mine at the bottom. That way, the
>>reader doesn't have to "scan up" the page. I also snipped out anything
>>that wasn't relevant to the replies by using some sort of "snip"

<snip/>

> I much prefer top posts actually.  (I'm just bottom posting now as a
> courtesy to you because I now know you prefer it, hehe)  I find it very
> frustrating when I've been keeping up with a thread to scroll all the way
> down to the new stuff at the bottom every time.  I like to see the newest,
> currently relevant text first, and if I'm not up to date with the thread I
> can scroll down and read the history if I want to.  That is the way I've
> always seen email done as well.  The current comments at the top and the
> thread history below.

You make a valid argument! I can totally see the sense in that. I've 
just been whipped into shape by the newsgroup nazis and don't want to 
irk them again :-)

> Of course if there is actually a consensus here regarding the 'correct' way
> to do this I will conform.  :-)

Uh oh -- now you did it. Everybody is going to have an opinion now. 
Brace yourself! :-)

--
Dan P
http://<broken link>

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Jellby wrote:

> Among other things, Dan P wrote:

<snip />

>>I thought that was cahones (sp?)!
> 
> If the Spanish speakers here will pardon the language, it's "cojones" 
> ("cajones" means drawers).

Oh :-) I got that from GTA Vice City.

--
Dan P
http://<broken link>

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