I appreciate it could be difficult to do but it would be a good challenge.

You do not need to compare every particle with every other particle as most
will be outside the gravitational field. I do not know the maths behind it
but I do know that the gravitaitional field drops off the further you get
from an object (thus making the math more difficult).

I lay down the gauntlet to anybody who fancies tackling this.

Dave

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> I appreciate it could be difficult to do but it would be a good challenge.
>
> You do not need to compare every particle with every other particle as most
> will be outside the gravitational field.
that's the problem: the gravitational field is infinitely large, although it
gets quite small after a distance.

cu!
--
camera{location-z*3}#macro G(b,e)b+(e-b)*(C/50)#end#macro L(b,e,k,l)#local C=0
;#while(C<50)sphere{G(b,e),.1pigment{rgb G(k,l)}finish{ambient 1}}#local C=C+1
;#end#end L(y-x,y,x,x+y)L(y,-x-y,x+y,y)L(-x-y,-y,y,y+z)L(-y,y,y+z,x+y)L(0,x+y,
<.5,1,.5>,x)L(0,x-y,<.5,1,.5>,x)               // ZK http://www.povplace.be.tf

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> I appreciate it could be difficult to do but it would be a good challenge.
> 
> You do not need to compare every particle with every other particle as most
> will be outside the gravitational field. I do not know the maths behind it
> but I do know that the gravitaitional field drops off the further you get
> from an object (thus making the math more difficult).

But it doesn't drop to zero IIRC...

Bye for now,
     Jamie.

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I do agree with yourself and Jamie, however for the purposes of a simulation
you can set it to be zero at a finite point. I know it is not strictly
correct, but we are not planning to launch a shuttle mission from the data
*g*

I am just interested to see if it is possible and what the outcome would be.

Dave

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Dave Brickell wrote:
> 
> I do agree with yourself and Jamie, however for the purposes of a simulation
> you can set it to be zero at a finite point. I know it is not strictly
> correct, but we are not planning to launch a shuttle mission from the data
> *g*
> 
> I am just interested to see if it is possible and what the outcome would be.

I think that can't be done. Because the point where gravitational force
becames zero should be set so far that no particles would escape from
system, otherwise the system will probably lose all particles (at least
from sight if camera is looking at fixed position). And intuitively I
think that limit should be so far that it wouldn't help any in speed.

This is just i feel thingie, tell me if I am wrong.

Matti

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Yes, I used POV exclusively to generate all the data points.  I'm fairly new
to POV so it took a few days to get the script to run the first time.  I
hope to make a lot of improvements to the code in the future.


"Mark James Lewin" <m._### [at] yahoocomau> wrote in message
news:3C8C45A5.160BCBD4@yahoo.com.au...
> Ha Ha! Neat! I like the ones that orbit one another. Did you use pov
script for
> the calculations?
>
> You've given me an idea for my own particle system too.
>
> MJL
>
>
> --
> prism{0,.1,30#local I=1;#while(I<30)#local B=asc(substr(// Mark James
Lewin
>
"#K?U_u`V[RG>3<9DGPL.0EObkcPF'",I,1))-33;<div(B,10)-4mod(B,10)+5*div(I,21)-
> 6>#local I=I+1;#end,-4pigment{rgb 9}rotate-x*90translate 15*z}//POV-Ray
3.5
>
>

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Thanks.  The first one was a little dull, but just add one unbalanced force
and then watch the fun begin.  :)



news:3c8c5917@news.povray.org...
> I like this one much more than the first one! The perturbation given by
the
> other body is very interesting!
>
> Congratulations,
>
> Fernando.
>
>

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The size of each particle was identical to the others, the masses were not
identical.  The white particle was set at 150% of the mass of the other
particles which were all the same.  I was thinking of adding some code to
automatically set the size of the particle according to the mass.
I think the formula is V=4/3*pi*R^3 so R=(3/4/pi*V)^(1/3).  I would have to
do a few tests to determine what density to use.

As to whether a large number of particles would settle down into one big
particle or a stable universe, it would depend on the initial conditions.


"Dave Brickell" <d.b### [at] ntlworldnospamcom> wrote in message
news:3c8ce77e@news.povray.org...
> Hi Draco
>
> I like this very much and was going to do something very similar a while
> back. Unfortunatly time and mathmatical problems did not allow me.
>
> Quick question.
>
> -Is the gravity of each particle proportional to its size/mass?
>
> If so I think it would be cool if you got rid of the ground plane then
> started with a few thousand randomly scattered particles. When 2 particles
> collide they join together to form 1 particle with the combined size/mass
of
> the original 2.
>
> I just wonder whether you would end up with 1 big particle or whether they
> would settle into a stable universe/solar system.
>
> Just wondering :)
>
> Keep up the good work.
>
> Dave
>
>
>

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Hi,

"Dave Brickell" <d.b### [at] ntlworldnospamcom> schrieb im Newsbeitrag
news:3c8ceef2$1@news.povray.org...
> I appreciate it could be difficult to do but it would be a good challenge.
>
> You do not need to compare every particle with every other particle as most
> will be outside the gravitational field. I do not know the maths behind it
> but I do know that the gravitaitional field drops off the further you get
> from an object (thus making the math more difficult).
>
> I lay down the gauntlet to anybody who fancies tackling this.
I've written a program in C for exactly this kind of simulation. It's capable
of doing eg a 1000 particle-simulation. It outputs a pov-scenefile from time
to time, which can then be rendered and joined to an animation. It also
supports
collision and fusion of two bodies to a bigger one. If someone is intereseted
i
can post the C-program or an animation which i've computed this way. But don't
expect any kind of Userinterface. I've everything hardcoded in the source
because
of lazyness :)
The Program still is very basic, it uses Forward-Euler integration. I plan to
extend it with Runge-Kutta integration for extra speed and precision.

That's it so far.
Tell me if anyone is interested and i'll post it.
Greetz

    Thies Heidecke

> Dave

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I'm interested in the animation. Hard-Code C isn't
very useful in IMHO for the big, wide world...


--
Tim Nikias
Homepage: http://www.digitaltwilight.de/no_lights/index.html

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