Propeller problem

Note: do NOT tell me to upload texture and use it. I don't have 10L =|. Plus, it won't be looking good. <- read carefully, please =)

Good daytime to you.
I want to make thing with 3 rotating parts (2 propellers, 1 axle). parts consists of multiply objects. When each part on itself, they rotate just fine. But when they are linked to main body, only their ex-parent objects rotate.

So is there any way to rotate only those parts? Constructive help would be appreciated.

And yet, again, do NOT[/] tell me to use texture.

Unfortunately the way that rotation works is that only the prim that has the llTargetOmega() call gets rotated and then only around its central axis (turn on local axis in the edit menu and edit link parts and you can see what I am talking about). You can easily make the axle rotate, but if you want propellers you'll have to make them so their central axis is over the axle. If you do that they might get out of sync as well. You can just make the blades 2 cylinders or 2 cubes and have them rotate about their axis.

I think you have eliminated all possible responses to your question.

Rotating multiple linked prims is very difficult, if not impossible. Although I am certainly not an expert at rotating things.

If it were me I would make the propeller and axle into one sculpted prim which can be rotated while linked to the rest, but that would require you to upload a sculptie map (texture.) If I made it, it would look as good or better than any prim propeller I could make.

Good luck, though. Maybe someone smarter than me knows how to do it.

I am not sure about your set up. But you might want to look at the page:
http://www.lslwiki.net/lslwiki/wakka.php?wakka=llTargetOmega

In my experience, the clue is to make the propella axis the root prim, at the whole thing (axis and blades) move just fine.

If you need to make the propellas part of a larger structure you are in trouble, but it can be handled. If that larger structure need to move (fast) as well, I know of no smooth way to do this.

A possible workaround might be to wear the propeller as a seperate attachment. TargetOmega should still work for that...

to use target omega (the smoothest movement) the linked rotationg part MUST be a single prim.

there IS another option, but it is neither as moth nor as efficient as the previous but WOULD allow you to move multiple prims in synch, around an axis.

however it requires multiple scripts to even approach the smoothness of target omega, and even then can be subject to jerkiness and slightly out of synch behaviors. plus there is a trade off between smoothness and speed.

How?
1) a timing script that sends a link message to the prims that need to move in synch
2) a separate receiver script for each prim that needs to move (this is so movements will be near simultaneous)

each receiver script calls llSetLocalRot when triggered, and updates the prims rotation around it's axis (you may need to use set primitive params to also move the object if the prims center is not the axis it moves around, cuts can obviate this need)

but you are much better off to sculpty your multiprim rotating parts or otherwise reduce them to single prims, and use target omega, which will be faster, more efficient, less laggy, and more realistic.

You could make/buy/use a sculpty propeller.

I agree.. a sculpted propeller and llTargetOmega really is the best way to do this. I've tried making something similar with a multiple-prim rotary fan, using the method Void describes above, and I found that keeping the individual prims' movements synchonized, even at low speeds, is more a matter of luck than anything else.

Because the simulator is moving each prim separately, how well it can keep them in synch depends on what else is happening on the sim; even minor discrepancies in timing look very odd, and the results are just so unpredictable.

Eventually, I gave up in disgust, bought a sculpted texture, slapped in llTargetOmega and cursed myself for wasting so much time trying to do it the hard way, when the easy way gave so much better results.

How's he gonna buy a sculpty prop when he can't afford to upload one texture?

which leads to the next suggestion... get a job! (or just camp long enough to pay the upload fee FHS)

I have made several propellas and other large composed structures which rotate using llTargetOmega - super smooth.

The "trick" is to let the structure be physical, and to let it be suspended in bearings. These bearings are best made as "ball bearings" - two small balls (5 cm) at each end of the axis around which the structure is to rotate - each small ball resting in a hollowed sphere with a hole diameter of around 35 cm, and a rest wall size at around 25 cm.

The resulting structure is very stable, and I have had them run for months. One can even move the bearings carefully, and the rotating structure will follow. It was the way in which I finally made a smooth windmill which could turn into the wind.

But, if you are at the level of attachments, this technique cannot be used, the precision of the physics engine is not good enough.

I would not reccomend this for a vehicle

He he - well, actually I did try to make an avatar powered scriptless vehicle (a rickshaw), where the wheels were done this way. The wheels turns as a consequence of the friction between the ground and the wheels. It looks kind of realistic, and as long there are not too many bumps in the surface it is OK. Too many bumps, and the wheels are thrown out of their bearings.

Bearings are a very powerfull building idea - I have build watermills, pistons, gears, and swings using bearings - and you can build some really amazing mobiles.