Ambient light is surrounding light that radiates from all directions. For information about how Direct3D uses ambient light, see Mathematics of Lighting.
A C++ application sets the color of ambient lighting by invoking the IDirect3DDevice9::SetRenderState method and passing the enumerated value D3DRS_AMBIENT as the first parameter. The second parameter is a color value. The default value is zero.
// This code example assumes that d3dDevice is a // valid pointer to an IDirect3DDevice9 interface. // Set the ambient light. d3dDevice->SetRenderState(D3DRS_AMBIENT, 0x00202020);