[SOLVED] Not again... can't rotate Vector

Ahem… I have a textured quad shown below as A. I want to rotate it so that it looks like B or C.

So I have this:

Vector3f dir = new Vector3f((float) Math.cos(angle), (float) Math.sin(angle), 0);

and then:

float rot=dir.x;
node.setLocalRotation(new Quaternion().fromAngles(0, 0, (float)Math.acos(rot)));

This works for getting B, but since C is negative I don’t get the desired result… I’ve tried with Quatertion.lookAt, but still wasn’t able to make sense of what I got…
Thanks for you patience :stuck_out_tongue:

Why turn an angle into a vector just to turn it back into an angle?

node.setLocalRotation(new Quaternion().fromAngles(0, 0, angle));

Else you will have to use atan2() but it’s really strange to find yourself using any of the atan() type methods.

1 Like

Because entity system :wink:
Now I have this:

public class Direction implements EntityComponent {
    private final Vector3f direction;
    private final float angle;
    private Quaternion facing;

    public Direction( float angle ) {
        this.direction = new Vector3f((float) Math.cos(angle), (float) Math.sin(angle), 0);

    public Vector3f getDirection() {
        return direction;
    public float getAngle() {
        return angle;

    public String toString() {
        return "Direction[" + direction + "]";

Sort of redundant, but at least I have the information on both forms when I need them.

Yeah, well… Vector3f direction seems completely unnecessary.

Well why not using this (I don’t know which ones right :smiley: )

Quaternion q;
Vector3f v = q.mult(Vector3f.UNIT_Z);

Or was it

Vector3f v = new Vector3f();
v = Vector3f.UNIT_Z.mult(q);

Note that it does make a difference, I only can’t remember :stuck_out_tongue:
Also note that you need to transform jme’s 3d coords to 2d, ie:

float x = v.x;
float y = v.z;