Is there a way to...

I want to create real moving wheels. (not just the texture rotating trick)

Is there a way to take a wheel that is already linked to a car and write a script that can do this.

When the car is moving forward, it will...

1.) get the velocity of the car
2.) translate the velocity into an object rotation speed
3.) rotate the object at that speed
4.) keep doing this constantly so that it stays with the changes of velocity.

Something kinda similar to the texture rotating trick here.

default
{
    state_entry()
    {
        llSetTimerEvent(0.20);
    }
    timer()
    {
        vector vel = llGetVel();
        float speed = llVecMag(vel);
        llSetTextureAnim(ANIM_ON | SMOOTH | LOOP | REVERSE, 0, 0, 0, 0, 1, speed*0.5);            
                    
    }
}

You can use llTargetOmega on child prims of a linked object, but the result may not totally be satisfactory, in that the resulting object can't be physical. I'd do it with textures, as you described.

The only problem with that is when I go in reverse, the textures spin forward. It looks weird.

Why not reverse the way the texture rotates, then?

Indeed. There's even a constant for it.

http://secondlife.com/badgeo/wakka.php?wakka=llSetTextureAnim

It sounds like he was talking about the suggestion to use llTargetOmega

Perhaps. But then again, this situation seems to be tailor-made for llSetTextureAnim. Most vehicles I see with spinning wheels use a combination of that and llSetRot for moving about.

I agree with Jeff here. Using llSetRot for creating a "spinning wheels" effect will look much less appealing then one with llSetTextureAnim (alot choppier), and it will generate many more object updates then are neceessary (llSetTextureAnim causes 1 update for every call, even when the anim is playing, whereas if you use llSetRot for this, youll need to call it very often, thus generating a significant number of partial updates.) llSetRot should be used to simulate the wheels effect when the car is turning left and right, and llSetTextureAnim the wheels spinning.
==Chris

I agree 100%.

But, if you do want to use llTargetOmega, read this

a link to that thread can also be found in the comments of llTargetOmega in the LSL WIKI

but even llTargetOmega is a "trick" (client-side) instead of real rotation of the physical object

Been dealing with rotations a lot with a couple of my new games. Biggest problem with the rotating textures is it's all client-side so it may appear different to multiple ppl. Tihs may nto be important with tires, but good to know.

If it is important, this can be dealt with my llTextureAnimation() followed with an llSetRot() at the end to set the object to the correct resting rotation.

This works smoother than it may seem it would. I use this method on my slot machine and looks very realistic.

Since there is no way to physically rotate with llSetRot() without using a PWM type motor and this method results in very unsmooth stepping, I'd abandon the idea.

If someone has a way to use llSetRot() alone to smoothly rotate an object and I've jsut missed a method, please let us know .