The ID3D10Device

 ID3D10Device *g_d3dDevice = NULL

Declares an ID3D10Device pointer as NULL. Later when we initialize D3D10 we will actually create it with the function D3D10CreateDeviceAndSwapChain(), but for now this is sufficient. But what exactly is the ID3D10Device? Our d3dDevice will be the access point to the video hardware. All of the methods involved in drawing to the screen and accessing VRAM are handled through this device.