Direct3D supports both flat and Gouraud shading. The default is Gouraud shading. To control the current shade mode, your application uses the D3DSHADEMODE enumerated type. See D3DRENDERSTATE_SHADEMODE.
The following code fragment demonstrates the process of setting the shading state to flat shading mode:
// This code fragment assumes that lpD3DDevice3 is a valid pointer to
// a Direct3DDevice3.
// Set the shading state.
lpD3DDevice3->SetRenderState(D3DRENDERSTATE_SHADEMODE,
D3DSHADE_FLAT);