[WIP][1.8.1, 1.9.1, 1.10.1, 1.11.0–2, 1.12.2–5] Principia—releases every new moon—n-Body and Extended Body Gravitation

[ZAJC3W]

  On 4/18/2021 at 7:41 PM, DanDucky said:

i7-4710HQ CPU @ 2.50GHz

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7 years old laptop CPU must be highlighting computational burden of principia.

On similar speed wise setup(AMD FX-8320) more than 6-8 ships in orbits was struggle too, 1000x time warp was fastest it would go.

Edited April 18, 2021 by ZAJC3W

[DanDucky]

7 years old laptop CPU must be highlighting computational burden of principia. @ZAJC3W

while in space it's perfectly fine, unrecognizable from stock, it's just when in atmosphere where it takes a hit.

Edited April 18, 2021 by DanDucky

[DanDucky]

  On 4/18/2021 at 11:51 AM, ZAJC3W said:

Check console for warnings/errors

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I don't see anything bad in console

I can deal with the lag at the beginning, but when it gets really bad I can't. hopefully there is a way to prevent principia from messing with atmosphere?

 

edit: the crash is from far, but the lag is from principia

Edited April 18, 2021 by DanDucky

[ZAJC3W]

Try reverting back to Principia version from before persistent rotation was implemented, 5-6 versions back from the top of my head. 

If I remember correctly that's when atmospheric forces started being used by Principia.

If this improves your experience then try raising an issue on GitHub, with logs and all. 

Imho atmospheric flight can be left for FAR to be dealt with, and Principia's rotation forces and all should kick in outside of it.

 

[pleroy]

  On 4/18/2021 at 11:45 PM, DanDucky said:

I don't see anything bad in console

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That would be because Principia does not log anything in the console.  As it stands the video is useless because it doesn't show the Principia UI.  It doesn't help that it ends before the point where the speed gets back to normal.

  16 hours ago, DanDucky said:

hopefully there is a way to prevent principia from messing with atmosphere?

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No there is not because Principia really does nothing at all with the atmosphere, it just gets the forces computed by FAR and applies them.

  16 hours ago, DanDucky said:

the lag is from principia

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How do you know that?  Do you have evidence that the problem goes away when you remove Principia, or are you speculating?  For all I know, it could just be that the FAR computations on an under-powered machine eat up all the resources.

  On 4/19/2021 at 9:20 AM, ZAJC3W said:

Try reverting back to Principia version from before persistent rotation was implemented, 5-6 versions back from the top of my head. 

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That's a terrible advice to give because (1) we don't support old versions, so if there is actually a bug it will never get fixed (2) the support of rotations has nothing to do with anything (3) integration with FAR, which could possibly have something to do with the problem was added at the same time as support for 1.4.4 -- who wants to revert to that?

  7 hours ago, ZAJC3W said:

Imho atmospheric flight can be left for FAR to be dealt with, and Principia's rotation forces and all should kick in outside of it.

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Cool idea, because, in fact, atmospheric flight is left to FAR.  As for the handling of rotations, believe it or not the laws of physics work the same whether you are in the atmosphere or not.

[DanDucky]

  On 4/19/2021 at 4:34 PM, pleroy said:

 It doesn't help that it ends before the point where the speed gets back to normal.

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it ended as soon as it crashed, there is no more footage. this is likely an issue with FAR as when I do not have far installed it does not crash at that point in flight (after booster separation). Additionally these issues with booster separation are persistent through ought craft files that produce a lot of "debris" Though I do know that this is not the place to ask and it is likely to do with my ass pc specs.

  On 4/19/2021 at 4:34 PM, pleroy said:

Do you have evidence that the problem goes away when you remove Principia

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yes, I can record some if u need it.

  On 4/19/2021 at 4:34 PM, pleroy said:

No there is not because Principia really does nothing at all with the atmosphere, it just gets the forces computed by FAR and applies them.

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okey dokey.

  On 4/19/2021 at 4:34 PM, pleroy said:

As it stands the video is useless because it doesn't show the Principia UI

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should I re-record with the ui open?

[eggrobin]

  On 4/19/2021 at 11:13 PM, DanDucky said:

should I re-record with the ui open?

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That might be slightly less useless; please also film a launch that doesn’t crash, so that we can actually see a transition to lower lag in space (without an intervening scene change), and figure out if it is correlated with something on the Principia side.

[DanDucky]

  On 4/19/2021 at 11:19 PM, eggrobin said:

That might be slightly less useless

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ok, I'm working on it. Sorry for all the confusion, I thought my problem laid within my excrementsty pc, so I never really provided that great info.

[pipai]

Running KSP 1.11.1 with Grassmann on Arch Linux.

Principia seriously lags while the Principia window is open during landing. This also affects Kerbals walking on the surface. No error logs, but I assume it's trying to calculate a bunch of trajectories and erroring out because we're landed.

Not a huge deal because you can just close the window, but it was fairly annoying until I found the workaround.

[eggrobin]

  On 4/25/2021 at 6:16 AM, pipai said:

Principia seriously lags while the Principia window is open during landing. This also affects Kerbals walking on the surface.

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This sounds like a symptom of the same issue as https://github.com/mockingbirdnest/Principia/issues/2957 and https://github.com/mockingbirdnest/Principia/issues/2953; it should be fixed in the next version, Green.

The Principia window spawns an asynchronous orbit analyser (this is used to give you a short description of orbit you are currently in, e.g., « circular semisynchronous Kerbin orbit » or something around those lines). This is not new, and is not a performance problem in itself (it runs fairly rarely and does so in the background). When the vessel lands, it becomes « unmanageable » by Principia, and all Principia-side state is destroyed. Due to a bug in our handling of the interruption of a numerical integration, the destruction of a running analyser is very slow, especially since Grassmann. This explains lag on landing. A walking Kerbal just keeps landing and taking off.

[DanDucky]

sorry, I forgot about this thread.

I a small amount of the lag was removed when I removed principia, but I think that was just all around lag from my computer being dogexcrements. sorry for all the confusions, somehow it got in my head that it was principia, idk

[eggrobin]

For the new moon (lunation number 264), the new release (Green) is out, fixing a few bugs (two crashes and a temporary but potentially very long freeze).

 See the change log for more details.

For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.

[Xurkitree]

Is there any way to extract Keplerian orbital elements from principia orbits at a particular time? I'm hoping to try out something and I'd like to know whether this is possible.

[OHara]

The elements of the Kepler orbit currently tangent to the Principia orbit (the 'osculating orbit') are saved in *.sfs files, so you can make named quicksaves at the moments you want, then in the quicksave files find VESSEL with your vessel name, then ORBIT to see the elements in the usual KSP format.

Just to be sure you noticed, Principia will draw the osculating Keplerian orbit; the option is in the main Principia dialog => KSP Features => Display patched conics

[eggrobin]

For the new moon (lunation number 265), the new release (Gröbner) is out.

It addresses one part of #2400, namely the lag on scene change far from 1951 in the absence of vessels. This means that @scimas’s custom initial states are no longer needed for late-starting games.

 See the change log for more details.

For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.

  On 6/2/2021 at 4:01 PM, Xurkitree said:

Is there any way to extract Keplerian orbital elements from principia orbits at a particular time? I'm hoping to try out something and I'd like to know whether this is possible.

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It depends what you mean by « Keplerian orbital elements » (and possibly on what you mean by « extract »), which in turns depends on what « something » is. In this perturbed Keplerian context, there are many kinds of elements, suitable for various applications.

In a lot of cases you care about mean elements. These encompass many definitions, but the concept is « elements that smooth out the perturbations that are on the scale of one revolution », so as to tell you something meaningful about the whole orbit around a given time ; they will still change over time (in particular you will encounter nodal and apsidal precession). The orbit analyser gives you mean elements.

Osculating elements do not really tell you meaningful things about the overall orbit, since they change significantly along the orbit; they are primarily useful as a way to express the exact position and velocity at the current time, for systems that prefer that to cartesian coordinates. KSP handles osculating elements, so this is what is surfaced in the stock UI, and in other mods (MechJeb, KJR, etc.).

[Blalo]

I know this has been asked over and over again, but is there a way to ONLY use the axil tilt part of this mod?

[mateusviccari]

  On 6/9/2021 at 7:08 PM, eggrobin said:

For the new moon (lunation number 265), the new release (Gröbner) is out.

It addresses one part of #2400, namely the lag on scene change far from 1951 in the absence of vessels. This means that @scimas’s custom initial states are no longer needed for late-starting games.

 See the change log for more details.

For the convenience of our Chinese users, the binaries can be downloaded either from Google Drive or from 腾讯微云.

It depends what you mean by « Keplerian orbital elements » (and possibly on what you mean by « extract »), which in turns depends on what « something » is. In this perturbed Keplerian context, there are many kinds of elements, suitable for various applications.

In a lot of cases you care about mean elements. These encompass many definitions, but the concept is « elements that smooth out the perturbations that are on the scale of one revolution », so as to tell you something meaningful about the whole orbit around a given time ; they will still change over time (in particular you will encounter nodal and apsidal precession). The orbit analyser gives you mean elements.

Osculating elements do not really tell you meaningful things about the overall orbit, since they change significantly along the orbit; they are primarily useful as a way to express the exact position and velocity at the current time, for systems that prefer that to cartesian coordinates. KSP handles osculating elements, so this is what is surfaced in the stock UI, and in other mods (MechJeb, KJR, etc.).

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Let's say I launched only one vessel and landed it on Mars in 1952. If I time warp to 2020 and save the game, is this lander included in the definition "absence of vessels" since it is landed, or will it have its trajectory recomputed all the way back to 1952 every time I load the game or switch scenes, despite being landed?

[CFYL]

Hi there! I don't know if this is a new question but, is principia a simulation of Newtonian Physics or does it take into account the theory of relativity?

[Delay]

  On 6/11/2021 at 12:50 PM, AllenLi said:

is principia a simulation of Newtonian Physics or does it take into account the theory of relativity?

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If anything, it's probably Newtonian. It's certainly not based on relativity as, for instance, Mercury's orbit doesn't exhibit apsidal precession.

[scimas]

  On 6/10/2021 at 10:48 PM, mateusviccari said:

landed it

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Landed vessels are not managed by Principia, meaning they don't exist as far as Principia is concerned. So no, landed vessels will not have any impact on Principia's computation.

[Sesshaku]

Is it normal to have a relative inclination to the moon of around 23-19º?? Going to the moon with Principia is a lot harder than other planets due to that. I've read people saying you can launch with a relative inclination of 0.3, But that never happens in my career.

I've read somewhere that it was a bug from RSS Expansion but I don't have that mod.

[pleroy]

  On 6/10/2021 at 10:48 PM, mateusviccari said:

Let's say I launched only one vessel and landed it on Mars in 1952. If I time warp to 2020 and save the game, is this lander included in the definition "absence of vessels" since it is landed, or will it have its trajectory recomputed all the way back to 1952 every time I load the game or switch scenes, despite being landed?

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Principia does not preserve the history of landed vessels, so your landed vessel should not cost anything in terms of scene change after you warp to 2020.

(Ah, I missed that @scimas had replied already.)

Edited June 12, 2021 by pleroy

[pleroy]

  On 6/11/2021 at 12:50 PM, AllenLi said:

Hi there! I don't know if this is a new question but, is principia a simulation of Newtonian Physics or does it take into account the theory of relativity?

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Newtonian.  Besides being computationally expensive (the Einstein–Infeld–Hoffmann equations typically require some kind of iterative resolution) relativity really has a minuscule effect compared to many other things that Principia doesn't take into account, like orbital decay or radiation pressure.

  On 6/12/2021 at 3:58 AM, Sesshaku said:

Is it normal to have a relative inclination to the moon of around 23-19º?? Going to the moon with Principia is a lot harder than other planets due to that.

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Principia accurately represents the characteristics of the solar system.  The inclination of the Moon on the ecliptic is 5° and the obliquity of the Earth is 23°.  Depending on how the two combine, going to the Moon may be hard, especially if you start, say, from Cape Canaveral.

[Sesshaku]

  On 6/12/2021 at 9:38 AM, pleroy said:

Newtonian.  Besides being computationally expensive (the Einstein–Infeld–Hoffmann equations typically require some kind of iterative resolution) relativity really has a minuscule effect compared to many other things that Principia doesn't take into account, like orbital decay or radiation pressure.

Principia accurately represents the characteristics of the solar system.  The inclination of the Moon on the ecliptic is 5° and the obliquity of the Earth is 23°.  Depending on how the two combine, going to the Moon may be hard, especially if you start, say, from Cape Canaveral.

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Cool, just wanted to confirm if it was just hard, or something was wrong with my install.

Any tips for launching from Cape Canaveral? Like at what angle should I aim an orbit and such. Or if it's possible to aim a polar orbit like the soviets from there. I am afraid I don't have much data on real historical maneuvres.

Edited June 12, 2021 by Sesshaku

[pleroy]

  On 6/12/2021 at 1:36 PM, Sesshaku said:

Any tips for launching from Cape Canaveral? Like at what angle should I aim an orbit and such. Or if it's possible to aim a polar orbit like the soviets from there. I am afraid I don't have much data on real historical maneuvres.

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I wouldn't know, I don't play Principia, I write it   This is a question that gets asked often on Discord (server KSP-RO, channel #principia), you might find hints there.

Edited June 12, 2021 by pleroy