Microsoft® Visual Basic® applications notify Microsoft Direct3D® that scene rendering is about to begin by calling the Direct3DDevice8.BeginScene method. BeginScene causes the system to check its internal data structures and the availability and validity of rendering surfaces. It also sets an internal flag to signal that a scene is in progress. After you begin a scene, you can call the various rendering methods to render the primitives or individual vertices that make up the objects in the scene. Attempts to call rendering methods when a scene is not in progress fail. For more information, see Rendering Primitives.

After you complete the scene, call the Direct3DDevice8.EndScene method. The EndScene method flushes cached data, verifies the integrity of rendering surfaces, and clears an internal flag that signals when a scene is in progress.

All rendering methods must be bracketed by calls to the BeginScene and EndScene methods. If surfaces are lost or internal errors occur, the scene methods fail and Err.Number is set to an error code. If BeginScene fails, the scene does not begin, and subsequent calls to EndScene will fail. When surfaces are lost during rendering, EndScene will fail.

To summarize these cases:

• If BeginScene returns any error, you must not call EndScene because the scene has not successfully begun.
• If BeginScene succeeds, but you get an error while rendering the scene, you must call EndScene.
• If EndScene fails, for any reason, you need not call it again.

For example, some simple scene code might look like the following example.

On Local Error Resume Next

Call d3dDevice.BeginScene
If Err.Number = DD_OK Then
    ' Render primitives only if the scene
    ' starts successfully.

    ' Close the scene.
    Call d3dDevice.EndScene
    If Err.Number <> DD_OK Then
        ' Code to handle error goes here.
    End If
End If