Matrix4f transform = new Matrix4f(rot);
transform.mul(drotX);
transform.mul(drotY);
Matrix4f tmp = new Matrix4f(rot);
tmp.invert();
transform.mul(tmp);
DirectionalLight[] lights = scene.getLights();
for (int i=0; i<lights.length; ++i) {
Vector3f direction = lights[i].getDirection();