[WIP][1.8.1, 1.9.1, 1.10.1, 1.11.0–2, 1.12.2–5] Principia—version ‎Καραθεοδωρή, released 2024-04-08—n-Body and Extended Body Gravitation

[pleroy]

3 hours ago, mateusviccari said:

Does this affect time warp speed?

Maybe.  Maybe not.

First, the speed-up only concerns the rotating-pulsating frame where we display equipotentials.  Second, if you have many cores, it won't make much of a difference, equipotentials will burn some of your cores but won't affect interactivity.  So we are left with the case where you don't have many cores (2-4) and you display equipotentials, then yes, there will be an improvement on warp speed.

[eggrobin]

A major issue was found in the previously released build for 伊藤: creating a manœuvre while the plotting frame was X–Y–Orbit would cause a crash, see #3689.

As a result, we have hotfixed the release; if you downloaded 伊藤 prior to this post, please click on the link in the OP or the GitHub readme to download it anew (the version string in the Principia UI should say 2023061805-伊藤-0-g2771ba5fa7f1d43341a5ca70adbd7f296449c300, not 2023061805-伊藤-0-gc3140c5f2bf7a8438e41cd5e3bcfcb2fd3f52356).

We apologize for the inconvenience.

[Wilds]

On 6/17/2023 at 5:29 PM, pleroy said:

This is not the log that we need.  As a matter of fact, for such a tricky bug we'd need a journal taken while the problem happens.  Details here.

ETA: We would actually very much like to be able to investigate this issue.  We have had a report years ago of a similar problem but we never managed to get to the root cause.  Interestingly, there was a Service Module.  So maybe that tells us something.  You would help us greatly by providing a journal.

I enabled journal, changed scenes, and launched a suborbital rocket with a 4 part capsule known for spinning. I reach around 550km apoapsis. At around 17mins into the flight, the capsule re-enters atmosphere. Spinning gets worse and worse, parachute is ripped off from high G spinning, and it krakens itself. I compressed it in 7zip format. If that is an issue, I can reupload.

https://www.mediafire.com/file/rkwgtdinquz85f5/JOURNAL.7z/file

 

Edited June 19, 2023 by Wilds

[pleroy]

38 minutes ago, Wilds said:

I enabled journal... I compressed it in 7zip format. If that is an issue, I can reupload.

https://www.mediafire.com/file/rkwgtdinquz85f5/JOURNAL.7z/file

Thanks.  I created issue #3697 to track this.  I verified that I could uncompress the journal.

PS: Don't expect a quick resolution, it's a big journal and probably a hard problem.

Edited June 19, 2023 by pleroy

[jd284]

For landing near my moon base, would a "Target-centered Moon-fixed" frame be feasible to add? The MCMF frame is somewhat helpful, but it is really difficult to judge the surface altitude, whether my landing burn will leave me 2 km above the surface or 2km below... and I can't tell easily how far from the target I will land either.

Alternatively, something like the standard Tgt-MO but with the target velocity set to the surface rotation velocity rather than its equivalent orbital velocity?

[Krazy1]

15 hours ago, jd284 said:

I can't tell easily how far from the target I will land either.

Just another option... use Trajectories mod and "show complete" option (or something like that) and it will plot the post-burn path and a red X at the landing spot. Also the landing target in KER shows a bullseye on the surface for the present landing spot along with time to impact and suicide burn countdown. You can do a pretty accurate and efficient landing with those tools. 

[Little 908]

How do you download this? My game is saying that there is game breaking bugs if it dont download it, thanks

[jd284]

6 hours ago, Krazy1 said:

Just another option... use Trajectories mod and "show complete" option (or something like that) and it will plot the post-burn path and a red X at the landing spot.

Does that know about Principia burns and trajectories? Because what I've tried so far just uses the faux maneuver node and assumes an instant impulse, whereas the real landing burn takes several minutes. So anything that doesn't correctly take the Principia burn into account will be off by hundreds of kilometers in my experience.

6 hours ago, Krazy1 said:

Also the landing target in KER shows a bullseye on the surface for the present landing spot along with time to impact and suicide burn countdown. You can do a pretty accurate and efficient landing with those tools. 

I guess I could try getting better at this... so far most attempts to land like this have ended in disaster, either lithobraking during the burn, or wasting fuel and running out, or just landing too far away. Might be the lunar masscons interfering or just KER not having the correct trajectory. Or maybe I just suck at suicide burns...

However I've gotten really good at rendezvous in orbit with planned Principia burns, ending up within no more than a few meters and under 10 m/s, so the option for applying that to landings as well would be really cool.

[Krazy1]

On 6/24/2023 at 9:03 AM, jd284 said:

assumes an instant impulse

Yes I think that's true. If you have a long burn it will be way off. The discrepancy between stock 2-body gravity and n-body when landing is negligible (typically) so the landing prediction will be fairly close for short burns. For example landing on Minmus with 2 distinct burns, one deorbit burn and then a suicide landing burn. But for long burns (like Tylo and Duna) there's a significant opportunity to add continuous-burn prediction for landing. Trajectories does atmospheric path predictions... Principia does continuous burns... an integrated tool would be excellent. 

On 6/24/2023 at 9:03 AM, jd284 said:

Or maybe I just suck at suicide burns...

I usually start the burn earlier than KER says and at lower thrust in favor of survival over efficiency. And I'm not surprised if I have to try 2-3 times for a low TWR landing... so a better way would be appreciated.

[Krazy1]

Just an upvote to address persistent rotation. I see https://github.com/mockingbirdnest/Principia/issues/2556 but it's quite old.

Persistent rotation really needs to have persistent SAS too. Otherwise, the stock "warp freeze" behavior is better IMO. An option to disable persistent rotation (until SAS is added) would be much appreciated.

One example, when trying to gather science in orbit I wrap-stop-warp-stop... frequently to get science in different biomes. I need to EVA to get EVA reports and interact with sensors. I need to find the door- I know where it was in daylight but the ship tumbles when I warp and it's on the dark side now and I can't get out fast enough to get the science before the biome changes. 

[MK2-DroneCore]

Bug(Maybe) Report:

Device:HP Laptop, 15.7GB of memory ,run KSP1 with Pricipia_伊藤 and RealFuel

Bug:

When I create a ManeuverPlan in the Kerbin-Center-Inertail Reference, my used-memory is about 13GB. But things changed in an unexpected way when I change my reference to Kerbin-Orbital(You know,which navigate you to an L-point) my used-memory suddenly jumped to  15.7GB, and the game crushed.

Is that a bug somehow? Or maybe you could give me some advice to play Principia in a not-very-good computer.

//  Edit is below //

Sorry I didn't notice that some player has already reported this problem.

Really a good mod maker, hope Principia will be better and better

 

Edited July 5, 2023 by MK2-DroneCore
The bug has been fixed already,but I didn't notice that

[AloE]

Thank you! for the new reference frame & orbital plane equipotential line plot, especially the EML...

For anyone who has not yet made a KSP GameData with Principia: fyi...this is an excellent addition to Principia &

combined with RSS is helpful for exploring Lunar DROs as well as the planned NRHO of the upcoming Lunar Gateway DSL & SLS Artemis missions...

 

		ESA, JAXA, NASA Gateway station DSL & SLS Artemis III Lunar NRHO	Forum Thread with saves & details
DRO 'Lunar Retro Square Orbit' (EML frame)	Conceptual 'surface' represented by the EML equipotential plane: Pink shows approx. 'Retro Square' path	DRO 'Lunar Retro Square Orbit' 18 years (MCI frame)	AP distance adjusts the corner sharpness of the 'Retro Square'

[jd284]

12 hours ago, AloE said:

combined with RSS is helpful for exploring Lunar DROs as well as the planned NRHO of the upcoming Lunar Gateway DSL & SLS Artemis missions...

Absolutely agreed!

Though I wish their mission documents explained the trajectories better, I haven't yet managed to do an even semi-efficient launch to get there. Basically always end up making the equivalent of a handbrake turn... really brings home the point why for 50 years, space travel has been almost entirely Hohmann transfers with maybe the occasional gravity assist.

[jd284]

I had an issue with my Earth orbital station suddenly vibrating rapidly after I switched to it from the tracking station, in order to do a rendezvous of a probe that had its nearest approach at that time. So both ships were in physics range, about 250m from each other.

The station seemed to vibrate at about half my framerate, seemingly switching between two states, "relaxed" and "agitated", finally ending up in the "agitated" state. At that point, multiple parts which still had their autostrut settings enabled, picked up the vibration and, being too far from equilibrium, it kept escalating to tear the station apart. Editing the savegame to disable autostruts didn't fix the vibration, but after shaking for a bit the ship eventually calmed down, with nearly all parts remaining out of alignment from each other even in subsequent time-warp.

However, turning on "hack gravity" in the tracking station before switching to the station, I was able to avoid the vibration: 1. Hack gravity, 2. switch to the ship, 3. while still loading press "Escape" to immediately pause when loaded, 4. once it's fully loaded unhack gravity and press "Escape" to resume. Maybe the pausing was unnecessary.

Since "hack gravity" hides the ship from Principia, I believe this might indicate a bug in Principia (version 2023061805-伊藤-0-g277). It may perhaps be processing both the probe and the station in consecutive frames and something is getting confused? I think in all prior rendezvous, which had no such problem, only one vessel was initially in physics range and the other came into range while the scene was already loaded.

While I lost the trajectory history of the station, it wasn't particularly interesting (just a ~250km LEO), so I'll keep playing for now and hope it doesn't happen again.

But if it's of interest, I can provide the samegame (using several dozen mods, including some custom ones of my own), or try to record a journal. I noticed a few things in the logs too:

Spoiler

The KSP.log file has the following entry, appearing twice for every time I loaded the savegame:

[ERR 17:35:00.265] Timing5 threw during LateUpdate: System.NullReferenceException: Object reference not set to an instance of an object
  at principia.ksp_plugin_adapter.MapNodePool.RenderMarkers (principia.ksp_plugin_adapter.DisposableIterator apsis_iterator, principia.ksp_plugin_adapter.MapNodePool+Provenance provenance, principia.ksp_plugin_adapter.ReferenceFrameSelector`1[ReferenceFrameParameters] reference_frame) [0x0006c] in <7270d71defee465385a53fa8988d42f8>:0
  at principia.ksp_plugin_adapter.PrincipiaPluginAdapter.RenderPredictionMarkers (System.String vessel_guid, principia.ksp_plugin_adapter.XYZ sun_world_position) [0x000cb] in <7270d71defee465385a53fa8988d42f8>:0 
  at principia.ksp_plugin_adapter.PrincipiaPluginAdapter.BetterLateThanNeverLateUpdate () [0x00043] in <7270d71defee465385a53fa8988d42f8>:0 
  at (wrapper delegate-invoke) <Module>.invoke_void()
  at Timing5.LateUpdate () [0x00023] in <4deecb19beb547f19b1ff89b4c59bd84>:0

Further the glog ERROR file has the following message (with slightly different values) for each savegame load:

E0711 17:36:43.004952 16006 matrix_computations_body.hpp:478] Difficult diagonalization: rows: 4 columns: 4
{-1.23284452533668900e+03 kg, +9.41466737458540592e-07 kg, +6.96834337787777258e-07 kg, -5.49126906291839134e-02 kg}
{+9.41466737458540592e-07 kg, -1.23284452449861510e+03 kg, +1.07289282524902774e-06 kg, -8.45474027450237031e-02 kg}
{+6.96834337787777258e-07 kg, +1.07289282524902774e-06 kg, -1.23284452515405155e+03 kg, -6.25783157239858667e-02 kg}
{-5.49126906291839134e-02 kg, -8.45474027450237031e-02 kg, -6.25783157239858667e-02 kg, +3.69853357498935566e+03 kg}
, stopping with: rows: 4 columns: 4
{-1.23284452594816230e+03 kg, +1.13686837721616030e-13 kg, +6.01345759870939719e-14 kg, -9.74992801083599622e-18 kg}
{-1.13686837721616030e-13 kg, -1.23284452594816230e+03 kg, -7.10542735760098924e-15 kg, -2.12730496490487696e-17 kg}
{-5.45998509716029296e-14 kg, -1.06581410364015003e-13 kg, -1.23284452594815775e+03 kg, -4.28040564578623436e-17 kg}
{+1.27122238243985609e-18 kg, -1.53560344092193722e-17 kg, -4.27334688455902673e-17 kg, +3.69853357784448281e+03 kg}

Not sure if these are actually related however.

 

[eggrobin]

For the new moon (lunation number 291), the new release (岩澤) is out.

The manœuvre markers (specifically their Frenet trihedra) are now draggable. Thanks to @Al2Me6 for this contribution.

See the change log for more details.

[olegst90]

Can I somehow decrease CPU load at the expense of precision? Is it controlled by Tolerance and  Steps settings?

[eggrobin]

For the new moon (lunation number 292), the new release (Jacobi) is out.

A pinnable hover tooltip is displayed when the cursor is hovered over a manœuvre marker, emulating the stock KSP node markers. Thanks to @Al2Me6 for this contribution.

See the change log for more details.

[budy]

I got it and I didn't have this problem the last time I had it but I cant get it to show on the nav ball when I make a maneuver. anybody know why its not showing and how to use it. all the tutorials I can find have it.

 

P.S. i think it has something to do with career mode.

Edited August 18, 2023 by budy

[jd284]

19 hours ago, budy said:

I got it and I didn't have this problem the last time I had it but I cant get it to show on the nav ball when I make a maneuver. anybody know why its not showing and how to use it. all the tutorials I can find have it.

It's an option on the flight plan window: "Show on navball".

[RedTyro]

Question about RSS/RO/RP-1 and Principia - the FAQ says not to install on an existing save, but then later it says to make sure all your ships are grounded.  I'm relatively early on in an RP-1 career and am considering adding Principia, but I'd hate to lose my progress so far.  I'm early in the game, though (1953 or 54) and I don't have any vessels in flight.  Is it too late to add Principia to this career?  Will the planet locations be accurate to the current date or will they start at Jan 1, 1951?  Will it break anything if I don't have any flights in progress?

Thanks!

[jd284]

On 8/29/2023 at 8:32 AM, RedTyro said:

Question about RSS/RO/RP-1 and Principia - the FAQ says not to install on an existing save [...]  Will it break anything if I don't have any flights in progress?

It will probably be fine, though of course you should make a backup of your save.

When I installed Principia I had a couple of ships in low orbit around Earth, and they were fine too [1]. This is just with RSS, no RO/RP-1 though, but I doubt they would make a difference here.

Principia recalculates the planetary positions every time a game is loaded, so those should be fine too. The main issue is really only transfer orbits which will no longer find their target and most likely crash at periapse without a course correction.

[1] However they were no longer aligned with the Moon's orbit, and of course as I found out it's no longer even possible to keep a station orbiting in the same plane as the Moon's orbit...

[RedTyro]

15 hours ago, jd284 said:

It will probably be fine, though of course you should make a backup of your save.

When I installed Principia I had a couple of ships in low orbit around Earth, and they were fine too [1]. This is just with RSS, no RO/RP-1 though, but I doubt they would make a difference here.

Principia recalculates the planetary positions every time a game is loaded, so those should be fine too. The main issue is really only transfer orbits which will no longer find their target and most likely crash at periapse without a course correction.

[1] However they were no longer aligned with the Moon's orbit, and of course as I found out it's no longer even possible to keep a station orbiting in the same plane as the Moon's orbit...

Awesome, I'll try it out.  Thanks!

[eggrobin]

For the new moon (lunation number 293), the new release (Jensen) is out.

No user-visible changes in this version as we have been laying the groundwork for a mechanism that would help optimize burns to meet certain criteria.

See the change log for more details.

[Krazy1]

I'm seeing a problem with AN not displaying on a highly eccentric orbit. I just installed Jensen. I'm sure at some point in the past (Principia version unknown) this was displaying as expected. Could you check this? 

Spoiler

KSP 1.12.5 with JNSQ. I'm coming back from Minmus and need to dock with a ship in equatorial LKO, and inclination change at AP is way less dV. I suppose I can guess where it is based on 180 deg. from DN. The orbit analysis doesn't show time to AN/DN. KER also doesn't give the soonest AN/ DN values (and based on conics).

 

[RiceCakes85]

Absolutely love this mod...is there any integration to create an alarm for a planned maneuver?  Im not finding one in the flight planner.