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Aeroboi

What causes shaking shreding krakeny things?

Question

I have this test vessel in orbit around Eve. Launching it, reloading it the consequences are the same.

vjjoBGS.png

Whenever I decouple this vessel weird stuff happens. First notice the black edges on the fuel tank adapters. And another thing, the camera is shaking, as in vibrating for no apparent reason.

ehe2EEC.png

For some reason the ore tank broke off seen in the lower right corner :confused:

cj1Q3qz.png

And sometimes the graphical glitch covers the entire vessel with black tints and stripes.

0Pfy8Xl.png

I've forgotten to screenshot the event but during one instance Gilly seemed to accelerate out of the solar system but only graphically, I could still get a encounter.
The kraken also seemed to auto decouple all the individual parts off of my ship. It wasn't explosive, all the parts just let loose from their joints. It was pathetic to look at.

Remember, the camera is shaking, virbrating or perhaps better interpreted as jittering.

I really want to test out this ship. What do you guys make of this one? Should I rebuild it? Any known editor applications that are known to trigger this behavior?

Thanks :)

 

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9 minutes ago, steuben said:

Do you have autostruts enabled?  If so what are they set to?

It's all varieties of autostrut and "root part" autostrut also which is the problem of course. Didn't thought of it since I haven't ran into the issue since "ever" and understood it would only happen when docking as opposed to undocking.

The craft works fine with heaviest and grandparent autostrut :)

Unfortunately however there are quite a few parts autostrutted to root as the docked vessels are part of a large multistage rocket. Many of these parts are better strutted towards heaviest and unfortunately root. I need this for the method I use to bring these stages along on the main lifter.

Is there a mod with which you can auto autostrut all parts or have some of them autostrutted with a action group? If not I have to individually re strut all the root strutted parts. It would be annoying.

 

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I use notepad to do a bulk changes of autostruts, deploy state, etc. A simple search and replace will get you what you need.

I've used Excel as well for it. But it is a bit more of a setup to get it done. I usually do a could of different changes at the same time if I have to invoke Excel.

The magic word is "autostrutMode = "

I've done all the work in the craft file. But, if you are careful and use backups, the principle should work as well in the persistent.sfs.

 

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3 minutes ago, mystifeid said:

Try Kerbal Joint Reinforcement.

I have on some installs. But this vessel is for a stock challenge so no KJR.

1 minute ago, steuben said:

I use notepad to do a bulk changes of autostruts, deploy state, etc. A simple search and replace will get you what you need.

I've used Excel as well for it. But it is a bit more of a setup to get it done. I usually do a could of different changes at the same time if I have to invoke Excel.

The magic word is "autostrutMode = "

I've done all the work in the craft file. But, if you are careful and use backups, the principle should work as well in the persistent.sfs.

 

Excellent idea. I feel more comfortable just changing the craft file for this. I'm not always ..... careful :D
Still, a mod for this would be even better.

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1 hour ago, Aeroboi said:

I really want to test out this ship. What do you guys make of this one? Should I rebuild it? Any known editor applications that are known to trigger this behavior?

Craft shaking themselves apart is something that just happens sometimes. I've encountered it since long before autostruts even were a thing. I don't know the reason, but it's very much present in stock.

Since autostruts exist, I've experienced it more frequently. However, with autostruts it's often possible to fix the issue by enabling/disabling them on selected parts, or setting them to another target.

However.... as you also report graphics glitches and other oddities, I'm totally at a loss as to reasons and remedies.

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One of the main reasons (in the olden days) used to be part clipping. But that shouldn't be a problem anymore ... "shouldn't". However, when I see parts vibrating, 95% of my brain says "autostruts" ... but 5% still says "maybe it's some kind of clipping thing that still happens".

 

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5 hours ago, Aeroboi said:

Is there a mod with which you can auto autostrut all parts or have some of them autostrutted with a action group? If not I have to individually re strut all the root strutted parts. It would be annoying.

For ships already in orbit, you'll have to edit the save file. You can use any text editor, like other people have said. I've also heard people talk about this tool, but I can't personally vouch for it: KerbalEdit

For ships you haven't launched yet, you can use the Editor Extensions Redux mod. It's good for lots of other things too. 

 

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3 hours ago, bewing said:

One of the main reasons (in the olden days) used to be part clipping. But that shouldn't be a problem anymore ... "shouldn't". However, when I see parts vibrating, 95% of my brain says "autostruts" ... but 5% still says "maybe it's some kind of clipping thing that still happens".

Not in my case, I assure you. Late night thought, pure conjecture: perhaps a floating point thing when a vessel happens to come out with actual, perfect symmetry?

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1 hour ago, Laie said:

perhaps a floating point thing

There is a probably-floating-point thing that gives this symptom, when very heavy things are attached to a very light thing, such as ore tanks attached around a strut.  The bug number is the new-ish 19530, but it has been around for at least a year.  The light part seems to be bounced around by rounding error in the very large reaction forces feels from the heavy things it is holding in place.

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Can changes in the hardware of the pc running the game cause differences in behaviour like this ?  If you're getting into rounding errors,  then surely FPS differences will influence those ?  Does the Unity physics engine take advantage of different code paths on different processors (AVX etc) which might cause differences in the way floating points get rounded up or down, different precision levels?

 

Edited by AeroGav

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19 minutes ago, AeroGav said:

Does the Unity physics engine take advantage of different code paths on different processors (AVX etc) which might cause differences in the way floating points get rounded up or down, different precision levels?

Basically nobody knows because Unity is distributed as closed-source, obfuscated binary blobs AFAIK.

 

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Graphics frames per second shouldn't affect the physics simulation, because KSP always simulates physics in steps 0.02seconds of simulated time, slowing the game clock if necessary
https://forum.kerbalspaceprogram.com/index.php?/topic/132637-fps-and-physics-timesteps/

Different hardware can round differently, or even different settings on the processor, but everyone seems to follow the IEEE 754 standard for single and double precision, so the size of round-off should be the same for everyone.  We are generally able to confirm each others bug reports, even on things like the wandering of orbital parameters.

I'm just guessing that Aeroboi's tanks might be mounted on a light part, but hope I guessed correctly because that would be easy to design around.

Edited by OHara
extra extra words

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