"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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Nice anim. For a really nice effect, try making the surface transperent, keep
the grid (maybe even make it a little finer), and place a starfield in the
background. Have you tried a square grid?

MJL

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then played with hundreds (thousands) of values for the gravitational constant
and tweaks to the starting velocity.

The problem is that instead of calculating the force every "infitesimal"
second, I'd set it up to do say every 10 weeks, 10 days, 10 hours, 10 secs or

model that system by only applying the force at every *HUNDREDTH SECOND*
instead of CONSTANTLY, then the direction of the force isn't going to be


into was being forced into one of these choices:


seeing how well Jupiter protects it.


But I'm intrigued that there could be some kind of "field effect" solution that



Bill DeWitt wrote:

> "Greg M. Johnson" <"gregj;-()56590"@aol.c;-()om> wrote :
> >
> > Bill's looks supercool but as he says it's just sin & cos.
> >
>

> my isosurface and use that to calculate the speed necessary to maintain
> orbit?

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"Mark James Lewin" <m_j### [at] yahoocomau> wrote in message
news:3B1AE4C6.F8BCBE0F@yahoo.com.au...
> Nice anim. For a really nice effect, try making the surface transperent,
keep
> the grid (maybe even make it a little finer), and place a starfield in the
> background. Have you tried a square grid?

    I tried the square grid and didn't like it, but I should try the
transparent thing, it sounds like it would be cool.

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"Bill DeWitt" <bde### [at] cflrrcom> wrote :
>
>     I tried the square grid and didn't like it, but I should try the
> transparent thing, it sounds like it would be cool.

    Tried it and didn't like it either. The other edges of the iso shows up.

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