Shading State (Direct3D 9)
Direct3D supports both flat and Gouraud shading. The default is Gouraud shading. To control the current shading mode, your C++ application specifies a member of the D3DSHADEMODE enumerated type for the D3DRS_SHADEMODE render state.
The following C++ code example demonstrates the process of setting the shading state to flat shading mode.
// This code example assumes that d3dDevice is a // valid pointer to a IDirect3DDevice9 interface. // Set the shading state. d3dDevice->SetRenderState(D3DRS_SHADEMODE, D3DSHADE_FLAT);