Oolite Bulletins

The Wiki wrote:

rotational_velocity

May be applied to a sub-entity, like the following entry to the subentity spines of the Weeviloid Hunter. Takes the form of quaternions. The following example enables rotation around the Z-axis.

Example:

<key>rotational_velocity</key>
<string>0.707 0.0 0.0 0.707</string>

I recall trying this in the past and it didn't work on a whole station, but I sometimes have hassle getting things to rotate at all so that's not a major reason not to give it a try anyway and check yourself.

The "station as a sub-ent" is another way (it's how I did the rotating gates in Lave Academy), but it gets fiddly keeping everything in the right place and getting docking correct.

Killer Wolf wrote:

nuts, is it?

i didn't realise there were subent specific attributes. or maybe i forgot, i'm getting old

well, what about creating the hermit as a tiny cube out of sight behind the dock, and have the rock etc as rotational-velocitying subents, would that be doable?

Definitely, you coud define a comms array as the 'main' ship, fixed in place, and get the rest of the rock as a rotating subentity of the comms array... still, it does sound much more sensible to allow different rotations for different stations in future, to avoid much fiddlitude...

sounds like either the "rotational velocity" should be able to be applied to ANY item, or the "rotating" attribute should have a speed element : would either of these be implementable in the next version?

Or just a rotational frequency in Hertz? (+ cw, - ccw)

I suppose the original Quaternions meant that rotation wouldn't necessarily be limited to the z-axis, but theoretically could be rotated about any arbitrary axis.

DaddyHoggy wrote:

Or just a rotational frequency in Hertz? (+ cw, - ccw)

I suppose the original Quaternions meant that rotation wouldn't necessarily be limited to the z-axis, but theoretically could be rotated about any arbitrary axis.

Why theoretical? Quaternions define a three dimensional rotation, and when using it on subentities, you can rotate them along any axis.

When you read the wiki correct, you see it says:

The following example enables rotation around the Z-axis.

So it says example, not only axis. And I tried in game: You can really use any axis. Quaternions are just difficult to understand, so everyone just picks that example instead of generating one themselves.

Anyway, as of 1.75 (and possibly 1.74.2) we will be able to have stations rotating at different speeds inside the same system, by using station_roll inside each station's shipdata entry. As an example
will make your rotating station spin at 1/8 the speed of a standard coriolis. (the standard roll is defined as 0.4)

Thargoid wrote:

And along similar lines, why is rotational velocity a quaternion when rotation is always around the Z-axis? Wouldn't it be simpler all around to just be an RPM number (positive or negative to allow clockwise or anti-clockwise rotation)?

it can be any axis : i've prepped a buoy for my new station that uses all 3 axes. of course, the rotation doesn't need to just be for a docking attribute, there's all kinds of effects it could be used for.

Kaks - excellent, that should open up a few nice effects. point to think about, i'm assuming the docking puter routine won't have a problem adjusting it's rotation speed? it's not hardcoded to use the existing rotation speed?

Killer Wolf wrote:

..point to think about, i'm assuming the docking puter routine won't have a problem adjusting it's rotation speed? it's not hardcoded to use the existing rotation speed?

Should not be a problem as it is hardcoded to match with the station roll of the particular station it is docking with.

It seems to work ok when the rotation is -0.4 too, (ie anti-clockwise as opposed to the usual & clockwise 0.4). I've definitely spent too much time docking, -0.4 felt 'unnatural'...

I'll crank the speed up to 2 & -2, and see what problems we get! 0.8 was already a bit too much for the manual docking computer!

I can report that I have sucessfully (and easily) docked with the bigger version of the hermit in both an Anaconda and even a Kirin XM. Not using a Caddy at the moment, but I guess that'd be the real acid test!!!

That default Material that Oolite surfaces the rock hermit with (because the model is missing it's texture info is pretty cool), if the red was blue we'd have ships that looked like the old ship identification chart that came with some versions of Elite !

Griff wrote:

That default Material that Oolite surfaces the rock hermit with (because the model is missing it's texture info is pretty cool),

Except when in the shade of a planet. My first encounter with your non-textured model was in such a situation. It was impossible to find the port. I flew a few circles around it without success.
At last I engaged my docking computer. That send me to a spot were I still could see no port. When fully colliding with the rock I cancelled docking and looked backward. Only than I could see the contours against a black sky, but still nothing from the tubing. The non-textured model definitely needs light for that.

Griff. They are full of beauty.