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Thread: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

  1. #1

    [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    The way i currently understand the game(correct me of I\'m wrong), is that only one body of mass influences the ship at a given moment. I would love to see both kerban and the mun have influence on my orbit at the same time.

  2. #2

    Re: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    This has been discussed dozens of times, and I feel I should warn you that quite a lot of people are tired of repeating this discussion over and over again, and will probably have snarkier responses than mine.

    At any rate, what you\'re basically asking for is a solution to the N-body problem, which is unfeasible if you also want to have the orbital map and time compression. It isn\'t that it can\'t be done, just that it would require reworking the vast majority of the game, and the only things it would change would be allowing Lagrange points. The current system, called the patched conics approximation, is more than adequate for our needs. It\'s so accurate, that\'s what NASA used to get to the Moon in real life.

    So, basically its a ton of work for very little reward, along with opening up the possibilities for tons of new bugs.

  3. #3

    Re: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    Beyond that, a lot of people who clamor for L points don\'t realize that they are pseudo-stable, and given the relative inaccuracy of Kerb ships and instruments (stock, of course Mechjeb changes things a bit), actually entering and maintaining station in a N-body modeled Lagrange point would take a degree of pilot/autopilot control that simply isn\'t possible in our little 1/6th scale universe filled with over-eager green dudes.

  4. #4

    Re: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    Wait, isn\'t it 1/10?
    "Without a resource system of some kind (mining or other), the VAB is the game. Looks like this game will absolutely require community mod packs even after it is finished." --JordanL

  5. #5

    Re: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    Er... yeah, it is. My bad. :-X

  6. #6

    Re: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    Just in case people come to complain about this being mentioned before; The search function is currently not working.

  7. #7
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    Re: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    Quote Originally Posted by Millitron View Post
    ...and the only things it would change would be allowing Lagrange points.
    I keep getting mildly annoyed at this particular notion in these discussions. While I agree that rewriting the orbital code at this stage would be prohibitively difficult (should\'ve done it while it was feasible), everyone seems to suddenly forget that the N-body solution does a whole lot more than just add L-points. It allows you to have, for instance, orbits that make sense. It allows you to plot a course between several bodies without compensating for drift you cannot see or SOI switches you cannot adequately account for. It allows you to overshoot the Mun without getting stuck in the Sun\'s SOI with no gravity of Mun or Kerbin to actually get you back. These simple important things are the ones being expected of the simulated orbits, not L-point silliness.

    Quote Originally Posted by Millitron View Post
    The current system, called the patched conics approximation, is more than adequate for our needs. It\'s so accurate, that\'s what NASA used to get to the Moon in real life.
    Indeed. See, patched conics can be made to work well in simple situations. They\'re plain math, not physics, easily solvable by the most primitive of calculators, which the trajectory computers of the Moon mission essentially were. Now, the crappiest korean-made cellphone has more processing power than those computers. We can afford a little more complexity. Patched conics are a neat, but ultimately clunky solution. Do you remember how many problems were had with this pure-math approach? SOI stutter, reversing orbits, orbits that cause ships to suddenly jump thousands of miles due to a periapsis point miscalculation, problems with SOI-switching debris in persistence, probably more that I cannot remember. With propagated orbits, the worst we would have to deal with would likely be accuracy jitter, orbit display versus flight time shenanigans and timewarp optimization, because there are no arbitrary points in the simulated orbit to break at. Squad just went for a solution that was simpler to implement at the time, which is very understandable, but so far it\'s the only thing undermining an otherwise near-perfect game of LEGO rocket science.
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  8. #8
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    Re: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    Patched conics have another advantage over an n-body system in that n-body orbits are almost always unstable, while orbits in the current simulation are only affected by one SOI, and are therefore not pulled into instability every time they pass the Mun.
    Kerbals and bits, anyone? -SynMonger

  9. #9

    Re: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    Quote Originally Posted by semininja View Post
    Patched conics have another advantage over an n-body system in that n-body orbits are almost always unstable, while orbits in the current simulation are only affected by one SOI, and are therefore not pulled into instability every time they pass the Mun.
    Which would be awesome! Of course if it ever was implemented I suppose there could be an option to turn it off...

    But it wouldn\'t happen for years...

  10. #10

    Re: [Suggestion] Multiple bodies of gravity have influence on ship at the same time

    Quote Originally Posted by semininja View Post
    ...and are therefore not pulled into instability every time they pass the Mun.
    I take it this 'instability' is the Mun affecting the orbit in a realistic manner?
    "Without a resource system of some kind (mining or other), the VAB is the game. Looks like this game will absolutely require community mod packs even after it is finished." --JordanL

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