4 ms·

Very nice to see an update to Orbiter after a long time. I'd really like to see it open sourced, but I guess that isn't happening. Setting it up properly is a

by exDM69 10y ago

Very nice to see an update to Orbiter after a long time. I'd really like to see it open sourced, but I guess that isn't happening. Setting it up properly is a bit of a mess right now, you need a 3rd party graphics engine called D3D9Client for that (or stick to using the old D3D7 engine). A lot of useful functionality is also 3rd party plugins you have to install from a variety of sites. You can play it right out of the box, but it's much better with 3rd party additions. If it was open source, perhaps it would be a bit easier to manage. ... now to toot my own horn for a bit: I've also been working on space simulation and orbital mechanics projects for fun (and some university classes earlier). If there's anyone here who likes Orbiter and/or Kerbal Space Program and is interested in related programming projects, get in touch (in HN comments or IRC/freenode for my HN username). Here's a quick screenshot of what I'm working on right now: http://ctrlv.in/884711 http://ctrlv.in/884711 (just started doing some 3d visualization earlier this week) And here's a two body orbital mechanics library I have been working on for a few years: https://github.com/rikusalminen/twobody https://github.com/rikusalminen/twobody (it should have everything you need to write your own KSP clone - look around in the different branches)

musgravepeter 10y ago
I'm a big fan of orbiting problems. There are some cool references on your gitlab - I'll need to dig through them sometime. Now some of my "tooting": I did a quick JS Kepler evolver (http://nbodyphysics.com/blog/2016/05/29/planetary-orbits-in-javascript/ http://nbodyphysics.com/blog/2016/05/29/planetary-orbits-in-...) and some very funky regularizing integration for the three body problem (http://nbodyphysics.com/blog/threebodyv2/ http://nbodyphysics.com/blog/threebodyv2/). Lots more side projects queued up - latest is a Unity Asset, Gravity Engine. Under "hugely ambitious" is trying to grok http://www.cds.caltech.edu/~marsden/volume/missiondesign/KoLoMaRo_DMissionBook_2011-04-25.pdf http://www.cds.caltech.edu/~marsden/volume/missiondesign/KoL... and do real three-body trajectories.
- exDM69 10y ago
  Good stuff and interesting projects. I spent a while going through your blog posts and other stuff. Do you mind if I drop you an email to exchange some ideas? Your Kepler's equation solver looks like a pretty standard textbook Newton iteration. I'm sure you're aware of its shortcomings, look at libtwobody for a more advanced solver (Laguerre-Conway) and the bibliography for the papers describing it. There's also a universal variable solver which doesn't have issues for near-parabolic orbits and handles elliptic/parabolic/hyperbolic orbits with no special cases. I've also got an interest in 3-body and n-body stuff but so far I've concentrated on the two body mechanics and dabbled a bit with simulating rocket launches. Your Unity Asset looks pretty interesting. Has it been popular? I've also considered making (code) assets for Unity, so please do share any experiences you've got.
  - kartikkumar 10y ago
    I've developed a lot of open-source space simulation code and got a few projects in the pipeline. Maybe worth having a chat? My email is in my profile. Anyone interested, feel free to ping me.
  - musgravepeter 10y ago
    The Kepler equation solver is the standard Newton iteration, which is ok until e gets larger. The actual N-body simulator in gravity engine allows for better orbits and the integrator is configurable (Hermite, Leapfrog) and easy to extend. Colwells book has LOTS on this subject too (https://www.willbell.com/MATH/mc12.htm https://www.willbell.com/MATH/mc12.htm) There are about 20 GE users so far, so it seems somewhat "niche". Offering an asset forces me to think a lot more about usability and documentation. I have recently added support for any solar system object and real world units - with tunable scaling. Not things I would have done if I was not making it an Asset. It's gratifying to get some uptake and the people who use it seem to like it. If you like Three Body stuff, checkout my iOS/Android three body app. LOTS of solutions to explore. (https://itunes.apple.com/us/app/threebody-lite/id951920756?mt=8/ https://itunes.apple.com/us/app/threebody-lite/id951920756?m... or https://play.google.com/store/apps/details?id=com.nbodyphysics.threebodylite&hl=en https://play.google.com/store/apps/details?id=com.nbodyphysi...)
    - exDM69 10y ago
      Thanks for all the good links. Get in touch if you want to chat about projects.

by exDM69 10y ago

musgravepeter 10y ago

I'm a big fan of orbiting problems. There are some cool references on your gitlab - I'll need to dig through them sometime. Now some of my "tooting": I did a quick JS Kepler evolver (http://nbodyphysics.com/blog/2016/05/29/planetary-orbits-in-javascript/ http://nbodyphysics.com/blog/2016/05/29/planetary-orbits-in-...) and some very funky regularizing integration for the three body problem (http://nbodyphysics.com/blog/threebodyv2/ http://nbodyphysics.com/blog/threebodyv2/). Lots more side projects queued up - latest is a Unity Asset, Gravity Engine. Under "hugely ambitious" is trying to grok http://www.cds.caltech.edu/~marsden/volume/missiondesign/KoLoMaRo_DMissionBook_2011-04-25.pdf http://www.cds.caltech.edu/~marsden/volume/missiondesign/KoL... and do real three-body trajectories.

exDM69 10y ago
Good stuff and interesting projects. I spent a while going through your blog posts and other stuff. Do you mind if I drop you an email to exchange some ideas? Your Kepler's equation solver looks like a pretty standard textbook Newton iteration. I'm sure you're aware of its shortcomings, look at libtwobody for a more advanced solver (Laguerre-Conway) and the bibliography for the papers describing it. There's also a universal variable solver which doesn't have issues for near-parabolic orbits and handles elliptic/parabolic/hyperbolic orbits with no special cases. I've also got an interest in 3-body and n-body stuff but so far I've concentrated on the two body mechanics and dabbled a bit with simulating rocket launches. Your Unity Asset looks pretty interesting. Has it been popular? I've also considered making (code) assets for Unity, so please do share any experiences you've got.
- kartikkumar 10y ago
  I've developed a lot of open-source space simulation code and got a few projects in the pipeline. Maybe worth having a chat? My email is in my profile. Anyone interested, feel free to ping me.
- musgravepeter 10y ago
  The Kepler equation solver is the standard Newton iteration, which is ok until e gets larger. The actual N-body simulator in gravity engine allows for better orbits and the integrator is configurable (Hermite, Leapfrog) and easy to extend. Colwells book has LOTS on this subject too (https://www.willbell.com/MATH/mc12.htm https://www.willbell.com/MATH/mc12.htm) There are about 20 GE users so far, so it seems somewhat "niche". Offering an asset forces me to think a lot more about usability and documentation. I have recently added support for any solar system object and real world units - with tunable scaling. Not things I would have done if I was not making it an Asset. It's gratifying to get some uptake and the people who use it seem to like it. If you like Three Body stuff, checkout my iOS/Android three body app. LOTS of solutions to explore. (https://itunes.apple.com/us/app/threebody-lite/id951920756?mt=8/ https://itunes.apple.com/us/app/threebody-lite/id951920756?m... or https://play.google.com/store/apps/details?id=com.nbodyphysics.threebodylite&hl=en https://play.google.com/store/apps/details?id=com.nbodyphysi...)
  - exDM69 10y ago
    Thanks for all the good links. Get in touch if you want to chat about projects.