[WIP][1.8.1, 1.9.1, 1.10.1, 1.11.0–2, 1.12.2–5] Principia—version ‎‎Колмогоров, released 2024-10-02—n-Body and Extended Body Gravitation

[SynX]

On 1/25/2020 at 8:15 AM, eggrobin said:

For the new moon (lunation number 248), the new release (Frege) is out.

• Celestial histories are now displayed as far as requested in the past (if available), rather than being limited to the time of launch.
• Miscellaneous bugs have been fixed (perhaps most visibly, the wild camera spin in the pause menu introduced in Fréchet).

 See the change log for more details.

We support two sets of versions of KSP: downloads are available for 1.8.1, and for 1.5.1, 1.6.1, 1.7.x. Make sure you download the right one (if you don't, the game will crash on load).

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

 

This mod is beyond awesome for geeks... Also since we have n body gravity, I wonder if the iconic 3-body motion is avalible. Another mod called Galaxy Unbound features a system with 3 stars, and it's disappointing that there isn't any three body motion.

Edited February 2, 2020 by SynX
adding information

[Agustin]

In the OP I can see a long trajectory display in tracking station or map view. I can´t do it in my pc increasing tolerance because it kills my memory. How am I supposte to use this feature?

[ArXen42]

@Augustin How much RAM do you have? I have 16GiB and KSP with just Astronomer's Visual Pack and Principia easily eats like 9GiB RAM. Principia has some heavy math under the hood, so I guess it may need considerable amount of RAM too.

 

Meanwhile, Kopernicus was just updated to support KSP 1.8.1. I'm sorry to ask noobish question, but what is the most up-to-date rescale (6.4x preferably) mod that is designed with compatibility with principia in mind (i.e. system stability)? I tested [1.4.2] [Kopernicus] [Sigma Dimensions] Realistic Rescale 1.1.1 and it seems to work fine (aside from some problems with Astronomer's Visual Pack that aren't related to Principia probably), but maybe there is something I'm missing and there is newer rescale mod out there?

Edited February 5, 2020 by ArXen42

[Croze97]

On 8/2/2017 at 1:34 PM, eggrobin said:

There is no way to do this, this UI comes with classes that Principia has to disable for things to work properly.

However, it provides replacements for all of those, see also the documentation on the subject.

• Principia does not support setting a celestial body as a target (since it has frame selection for interplanetary flight planning instead), but the option is provided under "KSP features" for use with other mods that require it, e.g. MechJeb. Click on "Select target celestial...", then click on the celestial.
• To focus view on a celestial body, simply left click on it.

• Principia comes with its own flight planning system; create manoeuvres there, and warp to them using the relevant button in the flight planning UI.
• Unfortunately it does not yet provide a tool to warp to an arbitrary point on the trajectory, but that can be worked around by making a flight plan, and putting a dummy manoeuvre at the desired point.

• To target a vessel, click "Select target vessel...", and click on the vessel.
• To switch to a vessel, target it, and press the "Switch To" button.

I see no 'Select target vessel' or 'Switch To' button. Am I blind? Running principia frege for 1.7.3 
 

https://imgur.com/a/SLoMD5H

[Croze97]

On 2/9/2020 at 4:06 AM, Croze97 said:

I see no 'Select target vessel' or 'Switch To' button. Am I blind? Running principia frege for 1.7.3 
 

https://imgur.com/a/SLoMD5H

Merr. I've tried getting in touch with someone to help me in the IRC twice in the past week and still no response here. I give up, no N-Body physics for me :c going to dedicate to an on-rails career mode and hopefully check back in a few months or something.

[eggrobin]

1 hour ago, Croze97 said:

I've tried getting in touch with someone to help me in the IRC

And, five days ago, you got an answer, from @Sir Mortimer (via the Discord bridge).

Quote

<Croze97> How to you actually switch vessel or set target? The wiki says there are buttons for it, and a tutorial in the l5 rendezvous video, but I don't see either buttons and the video just cuts to having the target set and never shows setting the target. I also used to just double click on crafts in map view to switch vessels (in principia) but sometimes

<Croze97> it doesn't work

<discord-> Sir Mortimer. — You need to unlock maneuver nodes. Upgrade mission control and the tracking station to level 2

 

Edited February 15, 2020 by eggrobin

[hypervelocity]

Hey guys, hope everyone's doing great today!

I am running into an issue on my Principia install and I think it might be related to this mod, however not entirely sure.

I am trying to complete a Moon Impact contract but whenever I try to hit Luna I end up going through the ground well below (~5km) surface (texture) level. When the craft finally crashes, the game also does automatically.

I have uploaded my KSP.log for your reference, hopefully this rough description rings a bell.

I am on KSP 1.7.3, RSS 16.4, Kopernicus 1.7.3-2 and am using Vannadin's RSS Textures 2.0.0 (not sure if relevant to mention, just in case).

Edited February 16, 2020 by hypervelocity

[pleroy]

6 minutes ago, hypervelocity said:

I have uploaded my KSP.log for your reference, hopefully this rough description rigs a bell.

These are not the logs we need.  

[hypervelocity]

ughhh -  so sorry for making you remind me of these things. I have created a github issue per instructions & uploaded relevant files to gist. I do not have a crash folder. Thank you in advance!

[ItsJustLuci]

Just curious about this mod, would this mod make luanr orbits in rss unstable? like, would spacecraft need reboosting to maintain altitude?

[eggrobin]

59 minutes ago, lk00david said:

Just curious about this mod, would this mod make luanr orbits in rss unstable?

Some of them will be unstable: see the orbit shown in the release announcement for Εὔδοξος for an example.

There are however low lunar orbits that remain stable (so-called frozen orbits), and there is extensive literature on the subject. For instance, the figure below, from Martín Lara's 2011 paper Design of long-lifetime lunar orbits: A hybrid approach, shows the stable eccentricity corresponding to a given inclination for lunar orbits with selected semimajor axes (for a frozen orbit, the argument of periapsis ω is either 90° or 270°, so that the value plotted on the vertical axis, e sin ω, is ±e).

Note that only 4 non-equatorial inclinations are permitted for stable circular (e = 0) orbits at any of these altitudes.

You can use the orbit analysis tool to see the mean orbital elements of your current orbit; by aligning those with the values given by that figure, you should be able to keep your spacecraft in low lunar orbit without need for long-term stationkeeping.

  

 

[AloE]

On 2/16/2020 at 12:24 PM, hypervelocity said:

Moon Impact contract but whenever I try to hit Luna I end up going through the ground well below (~5km) surface (texture) level....

Vannadin's RSS Textures 2.0.0

@hypervelocity some thoughts:

• Are you using a timewarp mod like BetterTimeWarp (old issue #1346 ) & does the same thing happen whether the vessel is in 'timewarp'  or not?  
•  
• your description also reminds me of @pleroy's extensive work with #1628: "The proper fix is to detect that we are moving too close to a singularity (because we are inside a celestial) and delete the vessel. I have started some work towards this (#1640). (You'd hope that KSP would do this detection, but no, if you warp fast enough through a celestial everything is cool.)"
•  
• also is this the RSS texture pack you are using  where there was issue #2447 where an older release apparently may have led to some issues "some of the normal maps will have problem with principia. I don't know why. problem solved. these normal maps are using the alpha map as x-axis normal map."?  if so a quick check to swap the Moon normal & height maps with the oness released in the main RSS_textures would be prudent...e.g. close KSP, temporarily swap in just the Moon files (at least the normal & height files..though I would also swap the color & biome files so that any screenshots would show which files are being used while running a given test) & delete the Kopernicus cached model for the Moon = GameData\RealSolarSystem\RSSKopernicus\Cache\Moon.bin , then reload KSP & see if the problem persists when you try to impact the default RSS model of the Moon..
•  
• In a very speculative/curiosity driven direction: In the tracking station, what value does the info icon show for the 'problem' Moon's radius...(ie. rule out a big mismatch between an expectation based on Principia's gravity model of where the Lunar surface should be...just incase somehow something made Kopernicus build & feed to Unity a physical model of a Moon that has a radius say ~5000m bigger than the radius for the moon used by the Principia RSS gravity model...which speculatively might interact, say with the issues tangled with & described in #1628 mentioned above)
•  
• (and to a lesser extent, also of RSS #87 )

Edited February 19, 2020 by AloE
typos & clarity revisions

[juanml82]

Is the download link live? I go to https://share.weiyun.com/5uxy0OG and all I get is a white page, as in, no website is being loaded

[pleroy]

22 hours ago, juanml82 said:

Is the download link live? I go to https://share.weiyun.com/5uxy0OG and all I get is a white page, as in, no website is being loaded

Hmm, it does the same for me.  But then when I go to Weiyun it tells me that the sharing link is indeed https://share.weiyun.com/5uxy0OG.  Maybe they are having problems.  Can you try with the non-Weiyun links (they go to Google Drive so may be hard to access in China)?

[juanml82]

1 hour ago, pleroy said:

Hmm, it does the same for me.  But then when I go to Weiyun it tells me that the sharing link is indeed https://share.weiyun.com/5uxy0OG.  Maybe they are having problems.  Can you try with the non-Weiyun links (they go to Google Drive so may be hard to access in China)?

Ah, I hadn't noticed the google drive download. Thanks!

[ganlhi]

Hello there! After many years of KSP I finally took the time to play with Principia, and it's fantastic! I now have the best of both worlds between the "storytelling" and custom experience of KSP and the true orbital mechanics I experienced in Orbiter a long time ago

I just have one concern: besides doing it manually, what is working to perform burns automatically? Obviously, Mechjeb can't do it. I was thinking of a custom script with kOS, but is there something else? And for kOS, does someone already has a working script (juste pointing in the right direction and burning at the right time for the right duration, nothing more)?

[AloE]

Happy sarbian nycat day (MM Feb 22) :-)

Also, in the process of drafting some saves to contrast (for some kids (me included ;-)) the special double sunrise (or sunset) points on Mercury with what I find to be an even more remarkable potential & rare possibility of 'somewhat perpetual combined sunrise AND sunset points" on some planets in the Trappist1 system I've been using Frege's fixed surface frame to help find the 'wobble' patterns of the 'Trappist1 Sun' in the sky.  The results surprised me enough, so below is a link to an album of some screenshots for easy viewing (I even created for myself a second simulation in KSP 1.8.1 to compare with the simulation in KSP 1.7.3 to check) (Ok I included the sarbian nycats too ;-):

Principia Frege In pursuit of Trappist1 System Rare "Sunrise-Sunset" points

(image below links to album which also includes some (ultra time warp draft ;-) ingame video capture of some examples of such points)

Edited February 23, 2020 by AloE

[eggrobin]

For the new moon (lunation number 249), the new release (Frenet) is out.

Nothing new this time; we have been working on the preservation of angular momentum, but it is not quite ready yet.

See the change log for more details.

We support two sets of versions of KSP: downloads are available for 1.8.1, and for 1.5.1, 1.6.1, 1.7.x. Make sure you download the right one (if you don't, the game will crash on load).

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

[hypervelocity]

On 2/18/2020 at 8:55 PM, AloE said:

@hypervelocity some thoughts:

• Are you using a timewarp mod like BetterTimeWarp (old issue #1346 ) & does the same thing happen whether the vessel is in 'timewarp'  or not?  
•  
• your description also reminds me of @pleroy's extensive work with #1628: "The proper fix is to detect that we are moving too close to a singularity (because we are inside a celestial) and delete the vessel. I have started some work towards this (#1640). (You'd hope that KSP would do this detection, but no, if you warp fast enough through a celestial everything is cool.)"
•  
• also is this the RSS texture pack you are using  where there was issue #2447 where an older release apparently may have led to some issues "some of the normal maps will have problem with principia. I don't know why. problem solved. these normal maps are using the alpha map as x-axis normal map."?  if so a quick check to swap the Moon normal & height maps with the oness released in the main RSS_textures would be prudent...e.g. close KSP, temporarily swap in just the Moon files (at least the normal & height files..though I would also swap the color & biome files so that any screenshots would show which files are being used while running a given test) & delete the Kopernicus cached model for the Moon = GameData\RealSolarSystem\RSSKopernicus\Cache\Moon.bin , then reload KSP & see if the problem persists when you try to impact the default RSS model of the Moon..
•  
• In a very speculative/curiosity driven direction: In the tracking station, what value does the info icon show for the 'problem' Moon's radius...(ie. rule out a big mismatch between an expectation based on Principia's gravity model of where the Lunar surface should be...just incase somehow something made Kopernicus build & feed to Unity a physical model of a Moon that has a radius say ~5000m bigger than the radius for the moon used by the Principia RSS gravity model...which speculatively might interact, say with the issues tangled with & described in #1628 mentioned above)
•  
• (and to a lesser extent, also of RSS #87 )

@AloE, thank you for your extensive research. In this case, item #3 did it - I removed Vannadin's texture pack & reinstalled RSS-Textures and I was able to impact the moon without any game crashes. Thank you for your suggestion!

Edited February 24, 2020 by hypervelocity

[scimas]

On 2/22/2020 at 5:57 AM, ganlhi said:

I just have one concern: besides doing it manually, what is working to perform burns automatically? Obviously, Mechjeb can't do it. I was thinking of a custom script with kOS, but is there something else? And for kOS, does someone already has a working script (juste pointing in the right direction and burning at the right time for the right duration, nothing more)?

Simple kOS approach works as long as you have unlocked manoeuvre nodes (in case of career mode). Lock steering to the manoeuvre vector. Calculate the time required to burn the necessary Δv. Start burning at the appropriate time and stop once the calculated time has elapsed.

Two problems with this:

1. Since the burn has to be calculated at full thrust (flight planner takes thrust limit into account, but only if it's in place before you created the manoeuvre, so it will be full thrust most of the time), and the values reported by kOS only change every physics tick, the burns will never be perfect.

2. The manoeuvre disappears as soon as the burn time, as determined by Principia, has passed. Which means you have to do some trickery in kOS to avoid errors with trying to lock to a node that doesn't exist. Which further decreases the possible accuracy of manoeuvre execution.

A function that does the node execution: https://github.com/scimas/KOS-Scripts/blob/master/Script/library/lib_manoeuvre.ks

Code to calculate the burn time: https://github.com/scimas/KOS-Scripts/blob/31f3a5e73358cdcd5972aa20ee5566283075d74c/Script/library/lib_navigation.ks#L230

On 2/23/2020 at 6:59 AM, eggrobin said:

we have been working on the preservation of angular momentum, but it is not quite ready yet.

Really excited about this! Is it supposed to conserve across time warp? And does it account for movement of resources around ship, like fuel or ore?

Edited February 24, 2020 by scimas

[AloE]

6 hours ago, hypervelocity said:

@AloE, thank you for your extensive research. In this case, item #3 did it - I reverted Vannadin's texture pack to stock RSS-Textures and I was able to impact the moon without any game crashes. Thank you for your suggestion!

you are welcome.  In that case, likely would have been better for me to have suggested for you to have just deleted the kopernicus \GameData\RealSolarSystem\RSSKopernicus\Cache\Moon.bin while you still had the 16k textures in GameData...did you happen to try that before reverting to the 'regular' RSS textures?

The Moon height map in VaNnadin's 16k texture pack is a massive 32bit DXT5 where as the stock RSS height map is a small 8 bit file (sadly the tools I have to split the RGBA channels do not work for a file that large for a detailed look)...so it might be that just deleting the Moon.bin would resolve the issue as well when using the 16k texture pack (PQS link below). 

As a habit, I delete my ModuleManager cache & .bin in the \GameData\RealSolarSystem\RSSKopernicus\Cache\ anytime I make any type of Kopernicus related .cfg or texture edit.  & remembering to create & use a new save is helpful when changing anything in the principia gravity model for a system...I tangled with that confusion when I mistakenly had not fully weeded out some of the old optimization "Trappist1 for Principia"  folders and/or saves lingering around in my plethora of various GameData folders...  

On 2/21/2016 at 6:34 AM, The White Guardian said:

But there is one step that nobody should forget: if you edit your planet's config file, after editing, ALWAYS remove the planet's 'Cache.bin' file, otherwise the old scaledspace model will stay in place while landing, which is a very eerie sight, though easy to fix.

 

 

[hypervelocity]

@AloE, very interesting what you point out in terms of clearing Kopernicus' cache. I did not try that before reverting to original RSS-Textures but I did test with previous versions of Vannadin's pack & concluded versions 1.2.1 & 2.0.0 work just fine - seemingly v 2.1.0 is causing the issues I described.

I am in the process of generating a save file for @pleroy to analyze using the faulty texture pack - I have created a github issue over at Principia's repository if you want to follow the case.

Thank's everyone, what a great community!!!

[pleroy]

On 2/23/2020 at 3:05 AM, AloE said:

The results surprised me enough, so below is a link to an album of some screenshots for easy viewing (I even created for myself a second simulation in KSP 1.8.1 to compare with the simulation in KSP 1.7.3 to check)

So @AloE I understand what you are trying to do, but I am not sure what I am seeing on these pairs of screenshots: what is on the left and what is on the right (I noticed different planet names and obviously different illumination)?

[pleroy]

16 hours ago, scimas said:

Really excited about this! Is it supposed to conserve across time warp? And does it account for movement of resources around ship, like fuel or ore?

It is conserved across time warp: the motion is completely continuous when warping and unwarping.  This makes it possible to do spin stabilization but also more exotic rotational motions (we've played a lot with the Джанибеков effect in our tests).

When resources move around the ship (or when the ship changes form), the masses and positions of parts change and Principia recomputes the moment of inertia; it then adjusts the angular velocity to preserve angular momentum (basically what figure skaters do).

In essence, Principia is the source of truth for the angular momentum and it will correct what is done by KSP/Unity to make the motion physically correct.

[AloE]

Just now, pleroy said:

makes it possible to do spin stabilization but also more exotic rotational motion...When resources move around the ship (or when the ship changes form), the masses and positions of parts change and Principia recomputes the moment of inertia; it then adjusts the angular velocity to preserve angular momentum

very much looking forward to that!  I had hoped that might be the answer (thanks  @scimas for asking the clarifying questions :-)