Convert from Pixels/twips to opengl coords

How can I normalize or convert pixel coordinates to OpenGl Cords for polygons.
I am building a 3d Object Creator, just in the works, and was wandering how to incorporate OGL

Sincerely: JEEP THANG

Does this have anything to do with texturing, or are your trying to project a windows point into OpenGL coordinates. If the latter use gluUnProject. If its texturing someone else has to answer. I haven’t explored it yet.