| clearDepth | 是否应清除深度缓冲区？ |
| clearColor | 是否应清除颜色缓冲区？ |
| backgroundColor | 清除时使用的颜色，仅在 clearColor 为 true 时使用。 |
| depth | The depth to clear Z buffer with, used only if clearDepth is true. The valid
range is from 0 (near plane) to 1 (far plane). The value is graphics API agnostic: the abstraction layer will convert
the value to match the convention of the current graphics API. |
清除当前渲染缓冲区。
This clears the screen or the active RenderTexture you are drawing into.
In most other situations, some camera is drawing something somewhere, and probably
is clearing already with the background color of the skybox. The cleared area is limited by the active viewport.
This operation may alter the model/view/projection matrices.
另请参阅：GL.ClearWithSkybox。