1、Vector3.back 即是Vector3(0, 0, -1)的简写

2、Vector3.down 即是Vector3(0, -1, 0)的简写

3、Vector3.forward 即是Vector3(0, 0, 1)的简写,也就是向z轴

4、Vector3.left 即是Vector3(-1, 0, 0)的简写

5、Vector3.one 即是Vector3(1, 1, 1)的简写

6、Vector3.right 即是Vector3(1, 0, 0)的简写,也就是向x轴

7、Vector3.up 即是Vector3(0, 1, 0)的简写,也就是向y轴

8、Vector3.zero 即是Vector3(0, 0, 0)的简写
