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I've been aware of people talking about Kerbal Space Program for years and years, but I lost interest in playing it when I heard it didn't do real N-body gravit

I've been aware of people talking about Kerbal Space Program for years and years, but I lost interest in playing it when I heard it didn't do real N-body gravitational calculations because they were too intensive. I still find that inexplicable. To me, it sounds like saying "our calculator only does basic arithmetic on four core machines, square roots are too slow".

messe 5y ago
Not really that inexplicable, it’s a video game. It’s not for computational reasons, but to make gameplay easier to reason about; because again, it’s a video game. The mechanics are simplified, yes, but patched conics is quite a good approximation for many cases, and great for developing an intuition for the basics. There is a mod that includes n-body calculations called Principia if you’re interested in that.
- deleted 5y ago
  [deleted]
garaetjjte 5y ago
There's mod though! https://forum.kerbalspaceprogram.com/index.php?/topic/162200-wip181-191-1101-and-1110%E2%80%932-principia%E2%80%94version-gr%C3%B6bner-released-2021-06-10%E2%80%94n-body-and-extended-body-gravitation/ https://forum.kerbalspaceprogram.com/index.php?/topic/162200...
- ericbarrett 5y ago
  It’s quite good as well, written in C++ for speed with new versions released every lunar cycle (!). I’ve done some Lagrange orbits with it in the Kerbol solar system. Doing it with Realism Overhaul and Real Solar System is a bit harder…
perihelions 5y ago
I'd push back against that interpretation of the developer's design choices. Kerbal's use of patched conic approximations greatly lowers the difficulty of the game (it is a game) for most players; it enables a simple and coherent UI/UX; and it guarantees fixed orbits that make difficult in-space rendezvous like the Apollo program's accessible. Like Minecraft cubes, it creates a reliable foundation of simple abstractions that people can reason about, and build complicated strategies on top of. (Wouldn't Minecraft be unplayable if instead of cubes, it was arbitrary user-defined convex polyhedra? It's like that). Upping the realism lowers the playability: games and simulators are subtly different things. Otherwise we'd all be playing STK/Astrogator instead of Kerbal, and AutoCAD instead of Minecraft, and sitting in city hall basements debugging spreadsheets in place of Cities: Skylines. The type of limitations that distinguish games from serious simulators are not accidents and not laziness, but deliberate design choices. I concede this makes certain interesting topics like Lagrange points / halo orbits, masscons, and orbital precession inaccessible. That's part of the tradeoff.

messe 5y ago

Not really that inexplicable, it’s a video game. It’s not for computational reasons, but to make gameplay easier to reason about; because again, it’s a video game. The mechanics are simplified, yes, but patched conics is quite a good approximation for many cases, and great for developing an intuition for the basics. There is a mod that includes n-body calculations called Principia if you’re interested in that.

deleted 5y ago
[deleted]

garaetjjte 5y ago

There's mod though! https://forum.kerbalspaceprogram.com/index.php?/topic/162200-wip181-191-1101-and-1110%E2%80%932-principia%E2%80%94version-gr%C3%B6bner-released-2021-06-10%E2%80%94n-body-and-extended-body-gravitation/ https://forum.kerbalspaceprogram.com/index.php?/topic/162200...

ericbarrett 5y ago
It’s quite good as well, written in C++ for speed with new versions released every lunar cycle (!). I’ve done some Lagrange orbits with it in the Kerbol solar system. Doing it with Realism Overhaul and Real Solar System is a bit harder…

perihelions 5y ago

I'd push back against that interpretation of the developer's design choices. Kerbal's use of patched conic approximations greatly lowers the difficulty of the game (it is a game) for most players; it enables a simple and coherent UI/UX; and it guarantees fixed orbits that make difficult in-space rendezvous like the Apollo program's accessible. Like Minecraft cubes, it creates a reliable foundation of simple abstractions that people can reason about, and build complicated strategies on top of. (Wouldn't Minecraft be unplayable if instead of cubes, it was arbitrary user-defined convex polyhedra? It's like that). Upping the realism lowers the playability: games and simulators are subtly different things. Otherwise we'd all be playing STK/Astrogator instead of Kerbal, and AutoCAD instead of Minecraft, and sitting in city hall basements debugging spreadsheets in place of Cities: Skylines. The type of limitations that distinguish games from serious simulators are not accidents and not laziness, but deliberate design choices. I concede this makes certain interesting topics like Lagrange points / halo orbits, masscons, and orbital precession inaccessible. That's part of the tradeoff.