egg changed the topic of #principia to: Logs: https://esper.irclog.whitequark.org/principia | <scott_manley> anyone that doubts the wisdom of retrograde bop needs to get the hell out | https://xkcd.com/323/ | <egg> calculating the influence of lamont on Pluto is a bit silly…
<queqiao->
⟨ferristik⟩ what is this game/simulation?
<queqiao->
⟨ferristik⟩ oh i see
<queqiao->
⟨Kirk (He/Him)⟩ Oh egg If I were to add more moons to Neptune, is there anything that needs to be done for Principia to recognize them?
<queqiao->
⟨egg⟩ They need a gravity model and initial state or we will crash. See the wiki page on config files.
<queqiao->
⟨Kirk (He/Him)⟩ How are the gravity models for the other gas giant moons that we don't have any information on handled? Just leave the spherical, or try to guess?
<queqiao->
⟨egg⟩ Don't try to guess, you'll hurt yourself.
<queqiao->
⟨charon_s.⟩ for the gravity model, generally speaking, we simply need mass, rotation period and axial tilt for a sphere, those parameters are easy to obtain just through observation. but if you want a more precise gravity model for a non-spherical body (aka geopotential model), considering no spacecraft have had orbit any gas giant moons, it's impossible. Nonetheless, there is a way to guess. Knowing the moon's dimension and volume, we can...
<queqiao->
... use a best-fit ellipsoid to roughly match its geopotential model for non-spherical gravity field.
<queqiao->
⟨charon_s.⟩ for the gravity model, generally speaking, we simply need mass, rotation period and axial tilt for a sphere, those parameters are easy to obtain just through observation. but if you want a more precise gravity model for a non-spherical body (aka geopotential model), considering no spacecraft have had orbit any gas giant moons, it's impossible. Nonetheless, there is a way to guess. Knowing the moon's dimension and volume, we can...
<queqiao->
... use a best-fit ellipsoid to roughly match its geopotential model for non-spherical gravity field.
<queqiao->
⟨sichelgaita⟩ For the record, I am somewhat concerned by the performance implications of adding more celestials (satellites, comets, asteroids, etc.) to Principia. For one thing, the integration of the solar system is quadratic in the number of celestials, so adding ~8 satellites to Neptune increases the cost of that computation by ~50%. Then the integration of the vessels is linear, so these extra satellites will cost you ~25% no matter...
<queqiao->
... where in the solar system you are. Finally, drawing the noodles will get more costly (how much depend on where they are, we don't draw them if they would be too close, so maybe satellites are fine).
<queqiao->
⟨sichelgaita⟩ I am not saying that it shouldn't be done, but maybe it should be packaged separately so that you can easily add/remove, say, the extra satellites of Neptune, and that the poor sap who is trying to land on the moon doesn't pay for these satellites that they will not even see.
<queqiao->
⟨charon_s.⟩ Partially agree with that. Adding so much celestials will definitely hit the performance, but from my experience, it will not hit too much. I test my mod with all the celestials added (total 141 for current version), it is not too laggy, but surely without those celestials the game will run smoother. I've take the concerns into consideration, and several versions before I already tweak the mod to package separately.
<queqiao->
⟨Kerbinator⟩ iirc your mod's correct way to use is, extract one or a few celestials, and then open a specific save for it
<queqiao->
⟨Kerbinator⟩ it's not meant to must be use in full, anyway
<queqiao->
⟨charon_s.⟩ correct. I also emphasized in the introduction.
<queqiao->
⟨Kirk (He/Him)⟩ Going off the satellite cutoff currently used by RSS, the only satellites of Neptune above the 200 km cutoff appear to be Triton and Proteus, of which Triton already exists. So, hopefully adding a single extra moon to Neptune won't cause too many issues