I have searched all of the internet but just couldn't find the answer. I am using LibGDX and this is part of my code that loops over and over:

public void render()
{
    GL11 gl = Gdx.gl11;

    float centerX = (float)Math.cos(yaw) * (float)Math.cos(pitch);
    float centerY = (float)Math.sin(yaw) * (float)Math.cos(pitch);
    float centerZ = (float)Math.sin(pitch);
    System.out.println(centerX+" "+centerY+" "+centerZ+" ~ "+GDXRacing.camera.position.x+" "+GDXRacing.camera.position.y+" "+GDXRacing.camera.position.z);
    Gdx.glu.gluLookAt(gl, GDXRacing.camera.position.x, GDXRacing.camera.position.y, GDXRacing.camera.position.z, centerX, centerY, centerZ, 0, 1, 0);

    if(Gdx.input.isKeyPressed(Keys.A))
    {
        yaw--;
    }
    if(Gdx.input.isKeyPressed(Keys.D))
    {
        yaw++;
    }
}

I might just be bad at the math, but I dont get it. Does someone have a good explanation and an idea about how to deal with this? I am trying to make a first person camera. By the way, the camera is translated by +10 on the Z axis. Currently when I run the application, this is what I get:

Watch video in browser | Download video (for those who cant download the video, everything shakes in a clockwise/anticlockwise action, depending on if I increase or decrease the Yaw value)

-Thank you.

[edit]

and with this code:

public void render()
{
    GL11 gl = Gdx.gl11;

    float centerX = (float)(MathUtils.cosDeg(yaw)*4);
    float centerY = 0;
    float centerZ = (float)(MathUtils.sinDeg(yaw)*4);
    System.out.println(centerX+" "+centerY+" "+centerZ+" ~ "+GDXRacing.camera.position.x+" "+GDXRacing.camera.position.y+" "+GDXRacing.camera.position.z);
    Gdx.glu.gluLookAt(gl, GDXRacing.camera.position.x, GDXRacing.camera.position.y, GDXRacing.camera.position.z, centerX, centerY, centerZ, 0, 1, 0);

    if(Gdx.input.isKeyPressed(Keys.A))
    {
        yaw--;
    }
    if(Gdx.input.isKeyPressed(Keys.D))
    {
        yaw++;
    }
}

it slowly swings from the left to the right. This approach worked for turning left and right for 2d games though. What am I doing wrong?