ID3DXMesh有normal开灯光全黑怎么回事？

oいばらの泪o

D3DLIGHT9 light;
        memset(&light, 0, sizeof(D3DLIGHT9));
        light.Type       = D3DLIGHT_DIRECTIONAL;
        light.Diffuse.r  = 1.0f;
        light.Diffuse.g  = 1.0f;
         light.Diffuse.b  = 1.0f;
        light.Diffuse.a  = 1.0f;
        D3DXVECTOR3 vecDir;
     vecDir = D3DXVECTOR3(0.0f,-0.3f,0.5);
         D3DXVec3Normalize( (D3DXVECTOR3*)&light.Direction, &vecDir );
         light.Direction = vecDir;
         Graphic::device->SetLight(0, &light);
         Graphic::device->LightEnable( 0, TRUE );
        Graphic::device->SetRenderState(D3DRS_LIGHTING, true);

        D3DMATERIAL9 material;
        ZeroMemory(&material, sizeof(D3DMATERIAL9));    // clear out the struct for use
    material.Diffuse = D3DXCOLOR(1.0f, 1.0f, 1.0f, 1.0f);    // set diffuse color to white
    material.Ambient = D3DXCOLOR(1.0f, 1.0f, 1.0f, 1.0f);    // set ambient color to white