[0.21] RotationFreeze

[Virindi]

Ever try to create a space station around Minmus? Have a ship run out of fuel in orbit of the sun and need to refuel it? If so then you might have encountered the spontaneous rotation problem. In high orbits, floating point inaccuracy causes craft to experience spontaneous rotational acceleration (even after stopping everything by turning on and off time acceleration).

Normally this is not a huge problem, since small rotations can be easily corrected by the use of SAS. However, when you are docking it can end up making docking impossible because the target craft will be rotating no matter what you do, and there is no way to tell it to hold attitude.

Enter RotationFreeze: a plugin which adds a simple toggle button which locks the rotation of nearby craft. Now, docking in orbit of the sun is just as easy as it is in low Kerbin orbit.

Source code is included in the zip file. MIT license.

http://kerbalspaceprogram.com/0-21-rotationfreeze/

[BigFatStupidHead]

So, no more needing to dock perpendicular to the plane of my orbit?

[Starwaster]

well, if there's a need for this that other people feel then kudos I guess....

but am I REALLY the only one who has not experienced this problem rescuing a craft orbiting the sun?

(just a little confused as to what this problem is that I'm supposed to be experiencing...)

[Virindi]

So, no more needing to dock perpendicular to the plane of my orbit?

It does not cancel rotation with respect to you, it stops it with respect to the reference frame (I believe this is the object you are in orbit of). So for instance, if your target is in an equatorial orbit and pointed at the ground, as it orbits it will no longer be pointed there. This is how you would expect things to work with an object in space that is not experiencing any rotational acceleration. As long as you dock at a speed faster than ridiculously slow you shouldn't have much problem with this sort of rotation, unless your orbital period is very small.

The problem that is solved is instead a 'bug' in the game which causes objects to experience phantom rotational acceleration, something which would not happen to a real object unless it was acted on by some force. This only occurs in the game when your orbital period is large.

[Virindi]

well, if there's a need for this that other people feel then kudos I guess....

but am I REALLY the only one who has not experienced this problem rescuing a craft orbiting the sun?

(just a little confused as to what this problem is that I'm supposed to be experiencing...)

I'll try to get a video of it. The amount of phantom rotational acceleration applied appears to depend on several factors, from number of struts on the craft to how long the game has been running, to how far out the craft is in the orbit. If I leave the game on for 12 hours with a craft in solar orbit that has 50 struts on it, the rotational acceleration will cause it to spin so fast the craft explodes. Obviously before it gets to that point I would typically restart the game. Depending on the situation though, it is possible to have enough of this rotational acceleration at game start that it is impossible to dock two craft.

It could have something to do with the fact that my computer is very slow, or you just aren't building things as complicated as I am. Dunno.

[Starwaster]

I'll try to get a video of it. The amount of phantom rotational acceleration applied appears to depend on several factors, from number of struts on the craft to how long the game has been running, to how far out the craft is in the orbit. If I leave the game on for 12 hours with a craft in solar orbit that has 50 struts on it, the rotational acceleration will cause it to spin so fast the craft explodes. Obviously before it gets to that point I would typically restart the game. Depending on the situation though, it is possible to have enough of this rotational acceleration at game start that it is impossible to dock two craft.

It could have something to do with the fact that my computer is very slow, or you just aren't building things as complicated as I am. Dunno.

Well I did build a station around Minmus using zzz's geodesic domes, greenhouse, FusTek modules and 14 large kethane tanks. A tug is semi-permanently docked to it. I did have a set of tanks explode when filled but at the time I blamed it on a kethane tank collision body issue. Since editing the tanks so that they're rotated 180 degrees when radially attached, I haven't had any problems with it so I'm not convinced it's the same thing.

On the other hand I did have ship's nuclear drive spontaneously fall off shortly after leaving Kerbin orbit. Is THAT due to your phantom forces?

Could be..... could also be linked to the disturbing revelation that a large chunk of stock parts have no breakingForce or breakingTorque assigned....

Anyway I think I'm going to go put something in orbit around the sun and leave it there for a few hours while I go do some chores. We'll see what transpires!

[Neutrinovore]

I think people are missing the point. I believe that Virindi is claiming that this plugin tames the Kraken!

We shall see, sir. We shall see.

[Virindi]

I think people are missing the point. I believe that Virindi is claiming that this plugin tames the Kraken!

We shall see, sir. We shall see.

Hardly. It only freezes other vessels, as in, completely prevents them from rotating, similar to being in time warp. It does not alter the current vessel. Also, the results can be hilariously bad if you impact one of these frozen vessels at high speed, since they will explode rather than rotate. Thus, it is a toggle

[Virindi]

Well I did build a station around Minmus using zzz's geodesic domes, greenhouse, FusTek modules and 14 large kethane tanks. A tug is semi-permanently docked to it. I did have a set of tanks explode when filled but at the time I blamed it on a kethane tank collision body issue. Since editing the tanks so that they're rotated 180 degrees when radially attached, I haven't had any problems with it so I'm not convinced it's the same thing.

On the other hand I did have ship's nuclear drive spontaneously fall off shortly after leaving Kerbin orbit. Is THAT due to your phantom forces?

Could be..... could also be linked to the disturbing revelation that a large chunk of stock parts have no breakingForce or breakingTorque assigned....

Anyway I think I'm going to go put something in orbit around the sun and leave it there for a few hours while I go do some chores. We'll see what transpires!

I don't know if your spontaneous explosions are caused by the rotation or not. I have only had my stuff explode for no reason a couple times. One time, I was moving a shuttle with two other shuttles strutted to the side of it to Laythe and it started spinning when I came out of time warp and parts flew off. The other time, I had a shuttle in Kerbin orbit around 100km and had had the game on for awhile and when I switched to the shuttle from the tracking station it exploded into a million pieces instantly. I didn't get a chance to see any rotation, but it could have been there.

If you're testing it out, be sure to use a ton of struts