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In article <3b17f4be$1@news.povray.org>, Bill DeWitt says...
>
> "Sander" <san### [at] stols com> wrote ;
> >
> > This looks great: how did you get the exact match of the orbits?
>
> Cheated. They are just arbitrary sin/cos figures.
>
> > I remember a C-program that came with all the sources necessary to
> > construct a 3-body animation. It could contain the necessara formulas,
> > but then again I think 3 bodies are not enough for you?
>
> Everytime I try to explain this to my wife she gets mad.
>
I should have said: heavenly bodies...
--
Regards, Sander
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"Sander" <san### [at] stolscom> wrote in message
news:MPG### [at] NEWSPOVRAYORG...
> In article <3b17f4be$1@news.povray.org>, Bill DeWitt says...
> >
> > "Sander" <san### [at] stolscom> wrote ;
> > >
> > > This looks great: how did you get the exact match of the orbits?
> >
> > Cheated. They are just arbitrary sin/cos figures.
> >
> > > I remember a C-program that came with all the sources necessary to
> > > construct a 3-body animation. It could contain the necessara formulas,
> > > but then again I think 3 bodies are not enough for you?
> >
> > Everytime I try to explain this to my wife she gets mad.
> >
> I should have said: heavenly bodies...
That would be even better...
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Bob H." wrote:
>
> The galaxy collision program I was trying to convert over from Basic to POV
> a while ago does gravity interaction in a sense. Each particle is the same
> mass but I'm sure that is a trivial matter. The stumbling block was due to
> my not knowing how to get the DIM (dimension) arrays changed, among other
> things. Was intended for 2D plotting of the 3D motions.
> Really needs to be more a orbit simulator.
>
> Pretty neat web pages here:
> http://burtleburtle.net/bob/physics/orbit101.html
>
> Bob H.
When I did a simulation, it looked exactly like the next to last one in the
link you shared here. My simulation was simply my flocking algo: at time t,
calculate the gravitational forces on every particle, and use this acceleration
to modify the current gravity. I spent weeks and never got a stable system, I
think, because I didn't conserve energy. This, I think would take calcs at
infinitely small delta t's. Or maybe something about potential energy, but
I'm confused. Your model would never decay, and allow a stray "Jupiter" to
wander into it? If so, what's the algo?
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In article <3b1800aa$1@news.povray.org>, Bill DeWitt says...
>
> "Sander" <san### [at] stolscom> wrote in message
> news:MPG### [at] NEWSPOVRAYORG...
> > In article <3b17f4be$1@news.povray.org>, Bill DeWitt says...
> > >
> > > "Sander" <san### [at] stolscom> wrote ;
> > > >
> > > > This looks great: how did you get the exact match of the orbits?
> > >
> > > Cheated. They are just arbitrary sin/cos figures.
> > >
> > > > I remember a C-program that came with all the sources necessary to
> > > > construct a 3-body animation. It could contain the necessara formulas,
> > > > but then again I think 3 bodies are not enough for you?
> > >
> > > Everytime I try to explain this to my wife she gets mad.
> > >
> > I should have said: heavenly bodies...
>
> That would be even better...
>
I _knew_ it would :)
--
Regards, Sander
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"Sander" <san### [at] stolscom> wrote :
> > > >
> > > I should have said: heavenly bodies...
> >
> > That would be even better...
> >
> I _knew_ it would :)
But I should mention that it is not strictly necessary.
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"Greg M. Johnson" <"gregj;-)56590\""@aol.c;-)om> wrote in message
news:3b18473f@news.povray.org...
> Bob H." wrote:
> >
> > The galaxy collision program I was trying to convert over from Basic to
POV
> >
> > Pretty neat web pages here:
> > http://burtleburtle.net/bob/physics/orbit101.html
>
> When I did a simulation, it looked exactly like the next to last one in
the
> link you shared here. My simulation was simply my flocking algo: at time
t,
> calculate the gravitational forces on every particle, and use this
acceleration
> to modify the current gravity. I spent weeks and never got a stable
system, I
> think, because I didn't conserve energy. This, I think would take calcs at
> infinitely small delta t's. Or maybe something about potential energy,
but
> I'm confused. Your model would never decay, and allow a stray "Jupiter"
to
> wander into it? If so, what's the algo?
Egads. I never said those were my web pages :-) Sorry, I didn't think
about the URL saying "bob" in it.
I can only dream to wish I could come up with the math for those myself.
And the galaxy collision simulation was copied from a magazine years ago.
Bob H.
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In article <3b18dd0b@news.povray.org>, Bill DeWitt says...
>
> "Sander" <san### [at] stolscom> wrote :
> > > > >
> > > > I should have said: heavenly bodies...
> > >
> > > That would be even better...
> > >
> > I _knew_ it would :)
>
> But I should mention that it is not strictly necessary.
>
I know...
--
Regards, Sander
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"Bob H." wrote:
> about the URL saying "bob" in it.
> I can only dream to wish I could come up with the math for those myself.
> And the galaxy collision simulation was copied from a magazine years ago.
Bill's looks supercool but as he says it's just sin & cos.
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"Greg M. Johnson" <"gregj;-()56590"@aol.c;-()om> wrote :
>
> Bill's looks supercool but as he says it's just sin & cos.
>
I wonder if you can use trace or something to get the angle of slope of
my isosurface and use that to calculate the speed necessary to maintain
orbit?
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"Bill DeWitt" <bde### [at] cflrrcom> wrote in message
news:3b1927b4$1@news.povray.org...
>
> I wonder if you can use trace or something to get the angle of slope
of
> my isosurface and use that to calculate the speed necessary to maintain
> orbit?
Interesting idea, perhaps so in a reverse way. You're unlikely to start
with the angle of slope and get to the correct orbital velocities, simply
because that isosurface would be probably be difficult to conform to the
real gravity well(s). This is all inexact science when dealt with in
POV-Ray I'd say.
Answering Greg, no, I bet it wouldn't remain stable. The program is based
on going into chaos in the first place, not meant for long duration orbits.
Besides, it's the same case in a way. You specify mass, velocity and
direction vector. To me that means hit or miss. :-)
I think a lot to do with that is why planetary simulators use things like
double precision math and constantly fine-tined equations.
Bob H.
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