中文说明：3D方式演示欧拉角通过鼠标就可以更改欧拉角的方位，其中代码适用于欧拉角方向余弦矩阵的转换。
English Description：
The Euler angle is demonstrated in 3D mode. The orientation of Euler angle can be changed by mouse. The code is applicable to the transformation of cosine matrix of Euler angle direction.