旋转四元数意味着：将另一个四元数乘以原始四元数的右侧或左侧（取决于要旋转的空间）。例如，如果希望向量先绕x轴旋转90度，然后绕z轴旋转90度，则可以使用以下代码实现这一点：

// your quaternion (rotation of 90 degrees around Z axis)
Quaternion rotation = new Quaternion().setEulerAngles(0, 0, 90);
// quaternion expressing rotation of 90 degrees around X axis
Quaternion x90deg = new Quaternion().setEulerAngles(0, 90, 0);
// concatenation (right-multiply) of the X rotation with the Z rotation
Quaternion result = new Quaternion(rotation).mul(x90deg);
// test: rotate (0, 0, 1) around X axis 90 deg, followed by Z axis 90 deg
// the first rotation will yield (0, -1, 0), and the second rotation (1, 0, 0) as a result
Vector3 v = new Vector3(0, 0, 1);
result.transform(v);
// v = (1, 0, 0)