@Override
                protected void controlUpdate(float tpf)
                {
                    float[] angles = this.getSpatial()
                            .getLocalRotation()
                            .toAngles(new float[3]);
                    angles[0] = angles[0] + (FastMath.PI / 500F);
                    this.getSpatial()
                            .setLocalRotation(new Quaternion().fromAngles(angles));
                }
Tests whether gamma correction works after a context restart. This test
generates a series of boxes, each one with a slightly different shade from
the other. If the boxes look the same before and after the restart, that
means that gamma correction is working properly.
<p>
Note that for testing, it may be helpful to bypass the test chooser and run
this class directly, since it can be easier to define your own settings
beforehand. Of course, it should still work if all you need to test is the
gamma correction, as long as you enable it in the settings dialog.
</p>

@author Markil 3
jme3-examples/src/main/java/jme3test/renderer/TestContextRestart.java