pleroy

@Agustin: You would notice differences if you were trying to replicate very accurately real-life missions: the old geopotential would exhibit drifts of hundreds of kilometers over a few months to a few years depending on the altitude. Things will get more interesting though when we extend this to the Moon, where the geopotential is very weird and affects orbit stability, or to Mars, where the position of Phobos and Deimos is currently bogus. More to come in future versions: stay tuned. @Someone2018: We started working on this in August. Making it correct was the first challenge, and then making it fast was even more interesting.

Thanks for the nice videos @AloE, and thanks for reporting the problem with 1b. I believe that I understand what is happening: there is a stupid mistake whereby the configuration of the integrator used in the game differs from the one we used to do the transit-time variation optimization. For the transit at JD2457721.38747, the former produces an effective transit at 20:34:47 (pretty much what you observe), the latter an effective transit at 21:18:08 (pretty much the correct value). Note that this probably tells us that the integrator is not converged for 1b, presumably because the step size we used is too large. Darn, we'll need to rerun the optimization... Created #1999 to track this. Follow the music there.

All working as intended. KSP is just a bit confused by our DLL because they are unmanaged and it tries to load them as if they were .Net assemblies.

Thanks for taking the time to find the mod causing the problem. From reading its description it's clear that it alters the physics, apparently in ways that are incompatible with Principia. We'll get in touch with @ferram4 to understand more.

@IncongruousGoat: This is a very bizarre bug, and not one that has been reported before. My gut feeling is that this is a nasty interaction with some other mod, but these problems are exceedingly difficult to debug. The thing that is especially strange is that Principia only translates parts, and never rotates them. So we could be guilty for the engine being off-centre, for instance, but it's harder to see how we would cause the antenna to rotate. If you can put your save on dropbox we'll take a look, but don't hold your breath, more likely than not we won't be able to pinpoint the cause.

I suspect that you have a mod that simulates a 32-bit architecture by claiming that the pointers are 32 bits. Something like that was in use when KSP didn't really work on 64-bit machines.

What do you mean by "when I use my build"? Build of what? Built how?

You need to have (1) a 64-bit processor (2) a 64-bit installation of Windows (3) a 64-bit installation of KSP. At least one of these prerequisites is missing (I suspect that you have a 32-bit installation of KSP).

@Clockwork13: As mentioned in the FAQs, you need version 6.0-2 of libc++. You must have a rather ancient version to be missing shared_mutex (it was added in the 3.4/3.5 timeframe).

@AloE: Yes, that's correct. That's mostly a round number (in JD) that's happens to fall shortly before the first observation of TRAPPIST-1. We run a fairly complex and expensive optimization to determine orbital elements that match the observed transits, so it's convenient to start a short time before the first observation. Also, many sources give dates like "7282.80570" where the leading JD245 is omitted.

@flyby2412: Cramer, the last version of Principia to support 1.2.2, can be obtained at https://goo.gl/XgRdRP. No support, no bug fixes, no questions answered. This being said, we recommend to use RP-1 with 1.3.1 and the latest Principia. Other people seem to have been successful with that setup.

@AloE: Regarding EVE and Scatterer: please see my response on the Principia thread. You want to download trappist-1 for principia δημόκριτος.zip which should do what you want.

Ah, thanks a lot for reporting this, @AloE. It turns out that while we coordinated with @GregroxMun when he was developing version 0.6.0 of his SLIPPIST-1 mod, we never fixed the link if the FAQs. So the version that you downloaded (trappist-1 for principia dedekind.zip) was designed for 0.5.x and had plenty of problems, one of which was an incompatibility with Kopernicus that caused the crash that you encountered. I have fixed the link in the FAQs to point to trappist-1 for principia δημόκριτος.zip. I suggest that you download this version and install it instead of what you have at the moment. It is better in a number of ways, in particular better alignment of the planetary textures, more realistic radius and atmospheres, data suitable for EVE and Scatterer, etc. (See PR #1856 and #1859 for details.) Apologies for the confusion caused by the outdated FAQs.

The UI has not changed substantially. There have been a number of improvements and fixes regarding memory usage, but it's hard to tell if it has anything to do with what you observed: if you don't submit bug reports, there is no guarantee that bugs will get fixed.

We were on vacation, this is a bulk reply to the thread regarding the ephemeris. Yes, we neglect the acceleration exerted by vessels on celestials and on other vessels. It does save a lot of computations. It's not as small as @Teilnehmer believes, even though the vessels can be 10^15 times lighter than the celestials, because vessels can be very close to each other (so the 1/r^2 factor matters). Note that saving the state of the celestials to a file would be much slower than just recomputing the whole thing. We are able to integrate about 3 million seconds/second, and as @scimas mentioned the file would be huge. Just say no to disk I/O. We'd be interested to know more about this. We have not observed noticeable differences in performance ourselves except at very large warp factors or at very large distance from the Sun. If you could open an issue on GitHub with details that help reproduce the problem, that would be great. Right. The ephemeris is used to (lazily) compute the trajectories of the celestials, and the trajectories of the vessels are then computed in the resulting gravitational field. That would defeat the purpose of the ephemeris, which is to determine once and for all the gravitational field in time and space, and then to integrate the vessels in that field. So the two forces that you mention are computed in two completely separate steps, and possibly at different points in time. As an implementation detail, the mass of the vessels is taken to be exactly 0 in the ephemeris so the forces are not helpful, what we need are the accelerations. To be a bit more specific (for RSS): we start from the positions and velocities, derived from JPL data, for all the celestials at a fixed point in time (1950-01-01); we integrate this configuration forward in time with a Quinlan-Tremaine symmetric linear multistep 12th order integrator and a time step of 10 minutes; for each celestial, we compute polynomials of degree between 3 and 15 to approximate the positions and velocities over 8 points (80 minutes) to 1 mm; these polynomials are constructed in the Чебышёв basis for accuracy and evaluated in the monomial basis for performance; when we need to compute the trajectory of a vessel, we use these interpolating polynomials to compute the position of each celestial.

Dunno, did you report it on GitHub? We fixed two bugs that could match that description (see the change log) but it's hard to know for sure. Nope, the solar system is constructed when you start a new game.

Probably not: we have been supporting 1.2.2 until mid-May 2018.

I tested it with 1.4.3. It works fine. Not tested with older releases 1.4.x but should be ok.

@王小谦同学: I was able to download your KSP.log file, but unfortunately this is not the log file that we need for debugging. Please see the FAQs for information on reporting bugs, and where to find our log files. Also, if you have a save that you could upload that might be helpful.

Use the FAQs, Luke! The FAQs have instructions for installing "Trappist-1 for Principia". Two caveats, though: Our mini-mod is on top of GregroxMun's mod, not on top of RSS, so it's incompatible with RSS (you cannot be in two solar systems at the same time, right?). If you are using 1.4.3 there's a glitch and it will fail to load because of an incompatibility with Kopernicus. Give us a few days to update the .zip file.

Thanks to @scimas for the reply. Public service announcement: the links to the releases are in the README.md file on GitHub. By looking at the history of this file, it's easy to find previous versions of the mod.

@Delay is right: if using Kopernicus, you want to look at this section of our FAQs.

Cramer for 1.2.2 is at https://goo.gl/XgRdRP. We won't be looking into bugs or otherwise supporting Principia versions that target 1.2.2, though.

It has not escaped our notice that the specific physics computations we have implemented immediately suggest a possible extension to support angular momentum conservations. As a matter of fact, quite a few of the classes that manage parts, vessels and pile-ups were designed with this in mind: "if, in addition to position and speed, we also had rotation and angular momentum, then it would still work because...". We just never got to implement it. A bit of design will be required, but I think that the foundation is sound.

@AlliedForth @hypervelocity @scimas: I have added some words to the FAQ but basically reusing a save that was not created with Principia will have strange results because the celestials will be in different places. It should not crash, but it may or may not be what you expect. This is unrelated btw to the notion of adding new vessels: vessels get created and removed all the time as part of normal gameplay (e.g. when stages separate or when a rendezvous happens) so this is something that we have to handle properly.