Culling State

To improve rendering performance, you can cull out (or remove) a primitive that faces away from the camera. For single-sided primitives, this saves rendering time because a back-face is not visible. To enable culling, you need to know the winding order of the vertices (typically counter-clockwise). This example will remove any primitive whose back face is facing forward (given a counter-clockwise winding order):

SetRenderState(D3DRS_CULLMODE, D3DCULL_CCW);