eggrobin

[WIP][1.5.1, 1.6.1, 1.7.x] Principia—version Fibonacci, released 2019-09-28—n-Body and Extended Body Gravitation, axial tilt

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@pleroy so, in principle, one only needs to come up with a height map of a body. And then they can convert it into the C and S coefficients by taking discreet spherical harmonic transform (does that exist?)? 

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Hi, it would be a good idea and it will make things a lot more easier if you add an option in the next update to add a maneuver node to the apoapsis and to the periapsis and to the ascending and descending nodes.

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4 minutes ago, SnailnamedSnail said:

and how about adding maneuver by click on the trajectory, like in stock KSP?

You can't add a maneuver node by clicking on the trajectory like stock KSP with Principia installed.

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That's because maneuver nodes still use patched conics and are thus useless for n-body physics.

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Hi there!

Hey there!

I am using KSP 1.3.1 with RealismOverhaul, Realist Progression 0, RSS and a bunch of other mods with Principia 2018120707-Erdős-0-g3e2334a95bcfc6869b5464ecda5ae48b5412dba0 .

Unfortunately, my Scene load times seem extremely long.
Without principia, a scene change takes 10 - 15 seconds.
With 2018081110-Desargues, every scene load took at least 1:30 minutes.
With 2018120707-Erdős, this became even worse. Now every scene change takes 3 minutes!!

During that time, the Memory usage drops quickly by 2-3 Gb and then slowly builds up these 2-3 Gb until the scene change completes.

My savegame has about 36 vessels, and the save file has a size of 10 mb.
Is this to be expected with principia? I know 1-3 minutes doesn't seem like much, but it seriously disrupts the gameplay.

Is this a bug? Is there a workaround for this?

(I have reported this on GitHub as issue #2038)

 

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Hello, first I'd like to say how amazing this mod is! But when I put the principia-master and latest principia gamedata files in the gamedata folder and tried to load a save (or create a new one) it just crashes. Is it because I installed it incorrectly? Or is it that I'm running ksp v1.6 (I could easily see it being that, I wouldnt expect a mod made for v1.5.1 to work in v1.6, I just want to check that Im installing it correctly).

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3 minutes ago, Kerbal Astronautics said:

Hello, first I'd like to say how amazing this mod is! But when I put the principia-master and latest principia gamedata files in the gamedata folder and tried to load a save (or create a new one) it just crashes. Is it because I installed it incorrectly? Or is it that I'm running ksp v1.6 (I could easily see it being that, I wouldnt expect a mod made for v1.5.1 to work in v1.6, I just want to check that Im installing it correctly).

2 things.

1. You only need the folder extracted from the zip that's offered in the README. No other files are needed (principia master or anything else).

2. Principia only works for the versions it is advertised for. So yeah, it will crash with 1.6.

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Just now, scimas said:

2 things.

1. You only need the folder extracted from the zip that's offered in the README. No other files are needed (principia master or anything else).

2. Principia only works for the versions it is advertised for. So yeah, it will crash with 1.6.

Awesome, thank you!

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Posted (edited)

2019-01-06

 For the new moon (lunation number 235, partial eclipse), the new release (Εὔδοξος) is out.

  • We have added an enhanced selenopotential in RSS, complete to degree and order 30; this means that the moon now has mascons, making some low lunar orbits unstable. Note that you will only get the new selenopotential when making a new save.
    As a concrete example, consider this screenshot of a lunar orbit, whose periapsis decreases by 3400 m over the course of 18 orbits because of the irregularities of the Moon's gravitational field (another dozen orbits later, the spacecraft collides with the Moon, between craters Spencer Jones and Spencer Jones W).cHLv5hR.jpg
  • Saves are now encoded in base64 instead of hexadecimal, making them smaller and faster to load.
  • We have rerun the TRAPPIST-1 optimization, this time with a small enough integration time step allowing us to accurately model the dynamics of the system. Thanks to @AloE for spotting the incorrectly-timed transits.
    The resulting system has residuals similar to those reported by Grimm et al., with χ² = 358.79 vs. χ² = 342.29 in the paper.

See the change log for more details.

We support two sets of versions of KSP: downloads are available for 1.4.x & 1.5.1, and for 1.3.1. Make sure you download the right one (if you don't, the game will crash on load).
 

Edited by eggrobin
off-by-one-year.

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@pleroy I don't think that what I'm describing here has changed over the past few releases, so I'll still post it.

 

I'm still using Ἐρατοσθένης, and in specific circumstances the prograde and retrograde markers aren't where the prograde and retrograde directions are. Telling SAS to hold retrograde, for instance results in anything but the retrograde direction.
Case in point:

D0cFFb4.png

I think this error is present at all times, but just not noticeable. In this case I was aiming for L4 of the Mun/Kerbin system, but a trans-munar injection works perfectly fine.

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16 hours ago, Delay said:

@pleroy I don't think that what I'm describing here has changed over the past few releases, so I'll still post it.

Hmm, this has been reported by @scimas a long time ago (#1868) but somehow it fell off our radar screen.  We have code to set the markers but apparently it stopped working with some KSP upgrade.  We should try to figure out what's happening.

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28 minutes ago, pleroy said:

Hmm, this has been reported by @scimas a long time ago (#1868) but somehow it fell off our radar screen.  We have code to set the markers but apparently it stopped working with some KSP upgrade.  We should try to figure out what's happening.

The markers are perfectly fine.

I manually executed the burn, aligned with both the retrograde marker and the maneuver node marker. As you can see, the burn was done correctly. It's the direction SAS aims at that's incorrect.

It seems to me that the markers are indeed pointing where Principia wants them to point, but SAS gets its prograde/retrograde/etc. directions from the stock KSP gravity model. Stock KSP looks at my orbit from an inertially fixed Kerbin frame, and in comparison to the Kerbin/Mun barycentric reference frame the directions are reversed.

 

Take a look at this really professional model of what I think is going on. The blue line represents the standard, patched conics trajectory. The arrows represent prograde.
MiDXl9l.png

Edited by Delay

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54 minutes ago, Delay said:

The markers are perfectly fine.

I manually executed the burn, aligned with both the retrograde marker and the maneuver node marker. As you can see, the burn was done correctly. It's the direction SAS aims at that's incorrect.

Yes, this is what issue #1868 is about, @pleroy was a bit confused.

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51 minutes ago, eggrobin said:

 @pleroy was a bit confused.

Well, the problem is a little confusing. Intuitively it seems as if the direction was correct and the markers are off, when in reality the opposite is the case.

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Hello n-body physics community -  and thank you for a great job, I like the Principia a lot. The player must finally think in the game))) - So my questions is simple and annoying:   Please any chance for 1.6.x? version of Principia, or any road map for the future...?   Good luck - and one more time, thanks you for great  mod...

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On 1/12/2019 at 11:05 PM, Delay said:

I think this error is present at all times

Unfortunately, this is not the case; in all my attempts to reproduce the issue, the SAS correctly pointed to the chosen marker as I changed the plotting frame (and thus the orientation of the markers).

I definitely remember encountering it myself, but I do not know how to reliably reproduce it; the steps given by @scimas in #1868 do not appear to work for me.

Do you have a save with no mods other than Principia and for which you have deterministic reproduction steps for this issue?

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33 minutes ago, eggrobin said:

Unfortunately, this is not the case;

What I meant by that is "if it is present, it is a negligibly tiny error in most situations", with going to L4 not being included in "most situations".

 

I'll try to recreate it in a copy that only contains Principia. Right now I have Scatterer, VSR, DistandObjectEnhancement, MM and EVE as well.

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I have experienced the same thing, but not only in the last releases. It's like the SAS prograde is linked to a different frame of reference in the navball. If you change the reference by clicking on the navball then the SAS prograde was fine. But when changing to the other reference then the SAS autopilot doesn't notice or something. 

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@eggrobin
Out of curiosity: I would like to know how high you guess the chance that Principia will do Trajectories-esque atmospheric predictions in the future, taking drag and lift etc. into consideration in atmospheres and allowing for (e.g.) aerobraking maneuvers?

I reckon that Trajectories itself only works with the standard KSP model, incorporating similar predictions into Principia would be a powerful feature and a good feature to spend time on in my opinion.

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@eggrobin @pleroy

I just had a problem with the flight plan.

I set up a node and the "ignition" timer was wrong. It was about 10 minutes behind; for Kerbin that was a noticeable difference. I then loaded a quicksave and now the timer is indeed counting down correctly.

Here's the maneuver I've planned. Unfortunately I made the screenshot after having loaded the quicksave.
XUYU0Hw.png

I know that my version is out of date, if this has already been fixed it would be nice to direct me to that version.

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And I think the Gui is giving me some kind of lock inputs which forces me to alt + f12.
Its when I change the tolerance and steps and tweak with it I think.
At least I think it's principia.

Edited by Agustin

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2019-02-04

 For the new moon (lunation number 236), the new release (Εὐκλείδης) is out.

Support for KSP 1.6.1 has been added.

This release fixes a long-standing issue (reported in November 2017 by @Agustin, in June 2018 on GitHub as #1868 by @scimas, and by @Delay in January 2018) where, under some circumstances, the SAS would not point the ship towards the markers (it would point the ship towards the position that the markers would have in stock instead).

It also fixes a relatively rare issue involving fragments of vessels getting close to the centre of a celestial on reentry (#2056).

See the change log for more details.

We support two sets of versions of KSP: downloads are available for 1.4.x, 1.5.1, & 1.6.1, and for 1.3.1. Make sure you download the right one (if you don't, the game will crash on load).

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@eggrobin Could you please change the names of the zip files themselves? They cause errors on opening because of all the greek letters, because winRAR atleast doesn't recognise the zip as a valid zip file. Changing the name removes this problem.

 

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