retrieve the constant's register index in the description table. This also
allows us to use a single uniform handle for both the vertex and pixel
shaders in a PS3 Cg program.

cannot used DirectX 10 because my video card only supports DX9, and there
is no compatibility layer. DX11 has feature levels for older hardware so
it would work with a DX9 card, but it's not available for WinXP.

tweak the triangle tutorial to make it shorter.