# Rotations - what is with the x coordinate?

Hi all,

I am building a small radar type thing, so I can find where things are. To do this I use:

1. I use the CameraNode.
2. I get the target node’s position relative to the camera, by subtracting the world position of the camera from the world position of the node.
3. I rotate it into the local space of the camera, by getting the world rotation of the camera node, converting it to a rotation matrix, taking the transpose of that matrix, and multiplying the vectors out.
4. I then plot the z,x coordinates on a plane and draw a line of height y at that position.

The problem I have is that for some strange reason the x coordinate seems to be flipped. or maybe the y coordinate is flipped. I don’t know. it just seems to be in the opposite handedness space.

have I done something wrong?

try here:

``` // note: cn = camera node             Quaternion q = new Quaternion(cn.getWorldRotation());             Matrix3f r = new Matrix3f();             q.toRotationMatrix(r);             r.transposeLocal();                                     Vector3f v = new Vector3f(400,0,0);             v.subtractLocal(cn.getWorldTranslation());                         r.mult(v,v);             v.normalizeLocal();             v.multLocal(400f); System.out.println("["+v.x+","+v.y+","+v.z+"]"); ```

here is a quick screenshot. I am inverting the x coordinate. It works.

[/img]

Looks good… but can you blow those planets up in fiery explosions??

(Sorry, it’s been a weird day.)

ahh… that will be released in a service pack

Excellent!