DirectX 11 coordinate system question

[tomtetlaw]

How do I make the coordinate system in DirectX 11 relative to the top left of the screen? I've setup an orthographic projection matrix, so that I can use screen coordinates but it makes more sense to me to have a top left origin, since I come from working with OpenGl.

I setup my projection matrix like this:
ww = the width of the window
and wh = the height of the window

projection = XMMatrixIdentity ();
projection = XMMatrixOrthographicLH (ww, wh, -1, 1);