vessel.SetPosition() issue :)

[EvilKot]

Greetings. Just wanna say sorry for my english, i hope you'll understand my question from code i posted below...

I've found a bug and looking for help to overcome it:

vessel.SetPosition(vessel.GetWorldPos3D());

sets the vessel a little bit behid from previous position.

For example i want my vessel to stay in current position:

public override void OnFixedUpdate()
        {
            base.OnFixedUpdate();

            vessel.SetPosition(vessel.GetWorldPos3D());
        }

but it starts flying backwards ( in vessel.transform.down direction) lol

This is my attempt to catch delta bug:

public override void OnFixedUpdate()
        {
            base.OnFixedUpdate();

            bug = Vector3d.Distance(vessel.GetWorldPos3D(), prevPos);       //here is it!   
            vessel.SetPosition(vessel.GetWorldPos3D(); //+ (vessel.transform.up * bug));   this will work every secon'd time   
            prevPos = vessel.GetWorldPos3D();

        }

The interesting thing is that "bug" is changing with speed, ship mass, and direction.

Any ideas?

[EvilKot]

Ah, solution always come after posting:

public override void OnFixedUpdate()
        {
            base.OnFixedUpdate();

            bug += vessel.GetWorldPos3D().magnitude - prevPos.magnitude;
            vessel.SetPosition(vessel.GetWorldPos3D() + (vessel.transform.up*(float)bug));           
            prevPos = vessel.GetWorldPos3D();           
        }

this works, but only in surface.

In orbit this is laggy as hell.

Edited November 22, 2013 by EvilKot

[EndlessWaves]

For example i want my vessel to stay in current position

That's almost certainly not the right way of doing whatever you're trying to do.

Hackness aside, I can think of a few possible reasons for this behaviour:

1. Different definition of position. Vessel represents a collection of parts, so how exactly do you define it's position? Even without getting into the detail of unity structure there are several options - root component, current control location, center of mass, geometric center. Have you tried the different functions giving the vessel's position (e.g. vessel.transform.position) and seeing whether they show the same behaviour.

2. Your code may be running before the physics and/or other classes (orbit), so if their are forces acting on the vessel that frame then they'll more them slightly from the position you specify. Ditto for the vessel.GetWorldPos3D() if it returns a pre-computed value.

3. GetWorldPos may be designed for more approximate duties and is less accurate then SetPos, hence your deviation.

P.S. I wouldn't call base.OnFixedUpdate() or similar methods.

[EvilKot]

Thank you, i'll look for another way

[EvilKot]

SetPosition is the only func i can use for my "mod", i'll try to find more accurate position.

[EndlessWaves]

Don't get too hung up on Vessel, it seems to be a class used to represent data about a collection of physics objects (part rigidbodies joined by Joints) and not an entity itself. Any methods it has that apply to physics matters are almost certainly convenience methods that loop through all the parts and issue commands to each of them.