Before rendering objects in a scene, clear the viewport on the render-target surface or a subset of the viewport. Clearing the viewport causes the system to set the desired portion of the render-target surface and any attached depth or stencil buffers to a desired state. This resets the areas of the surface that will be rendered again, and it resets the corresponding areas of the depth and stencil buffers, if any are in use. Clearing a render-target surface can set the desired region to a default color or texture. For depth and stencil buffers, this can set a depth or stencil value.

Use the IDirect3DMobileDevice::Clearmethod to clear the viewport.

Note:

Applications that render scenes covering the entire area of the render-target surface can improve performance by clearing the attached depth and stencil buffer surfaces, if any, instead of the render target. In this case, clearing the depth buffer causes Microsoft® Direct3D® Mobile to rewrite the render target on the next rendered frame, thereby making an explicit clear operation on the render target redundant. However, if your application renders only to a portion of the render-target surface, explicit clear operations are required.

See Also