Angle

Troubleshooting General Help
1

Im trying to get the Y rotation from a object to and transfer it to another.



so, to get the angle im using:

localRotation.toAngleAxis(new Vector3f(Vector3f.UNIT_Y))



and to set:

Quaternion quaternion = new Quaternion();
quaternion.fromAngleAxis(rotation, Vector3f.UNIT_Y);
setLocalRotation(quaternion);
localRotation.normalize();



it works well till 180 degree, then it starts to rotate counter-clockwise, then when it back to 0 dregree it back to normal.

Someone knows what I'm doing wrong?
2

Come one guys… there's such a few documentation and the tutorials are so out of date…

so i just have you ppl… give me a hand here.

3
hvilela said:

Im trying to get the Y rotation from a object to and transfer it to another.


if the X and Z rotation of the 2nd object are always, 0 something like this could work.


        box2.getLocalRotation().y = box.getLocalRotation().y;
        box2.getLocalRotation().w = box.getLocalRotation().w;


4

i also tried a few other ways but i couldn't get it to work hehe.

my math kung fu is very limited :frowning:

5

Yes, the other 2 axis are always zero, and your code does works.

But, I was wondering how to get just one value that represents the rotation on the Y axis, because I'm transfering it over the net (it's a multiplayer game), so it would reduce my data size.

My "get" code works well, juts my "set" code is buggy.

6

If you want to just transfer the value accross the net as an angle ( eg 180 degrees ), then in JME you will need to convert that angle to radians



getLocalTranslation().y = FastMath.DEG_TO_RAD * 180;

7

My Problem is not about convert to degree, I can transfer the value in radian too.

My problem is that on a quaternion the Y value by it self do not represent all the rotation on the Y axis. That happen because a quaternion is represented by 4 values instead 3: x, y, z and w.



The code above can get the REAL y rotation:

localRotation.toAngleAxis(new Vector3f(Vector3f.UNIT_Y))



But now I can't set it.
8

I think both funcions was wrong.

Now I discovered that a quaternion can be build from 3 angles and transformed to this too, so now it's solved:



Get:

localRotation.toAngles(null)[1]



Set:

setLocalRotation(new Quaternion(new float[] {0, rotation, 0}));