粒子系统的排序模式。
| None | 无排序。 |
| Distance | Sort based on distance to the camera position. For orthographic cameras, this mode is the same as sorting by depth. |
| OldestInFront | 将最早的粒子排序到前面。 |
| YoungestInFront | 将最新的粒子排序到前面。 |
| Depth | Sort based on depth from the camera plane. |