Antialiasing is a method of making lines and edges appear smoother on the screen. Direct3D supports two ways to perform antialiasing, called edge antialiasing and full-scene antialiasing. For details about these techniques, see Antialiasing in the Common Techniques and Special Effects section.
By default, Direct3D default doesn't perform antialiasing. The D3DRENDERSTATE_ANTIALIAS render state can be set to one of the members of the D3DANTIALIASMODE to enable full-scene antialiasing. (The default value, D3DANTIALIAS_NONE disables full-scene antialiasing.)
To enable edge-antialiasing (which requires a second rendering pass), set the D3DRENDERSTATE_EDGEANTIALIAS render sate to TRUE. To disable it, set D3DRENDERSTATE_EDGEANTIALIAS to FALSE.