| clearDepth | Whether to clear both the depth buffer and the stencil buffer. | 
| clearColor | Whether to clear the color buffer. | 
| clearFlags | Which render targets to clear, defined using a bitwise OR combination of RTClearFlags values. | 
| backgroundColor | 要清除的颜色。 | 
| depth | 要清除的深度(默认值为 1.0)。 | 
| stencil | Stencil to clear with (default is 0). | 
添加“清除渲染目标”命令。