Cad interface

hello everyone, i am working on a construction cost estimation software, which works with a cad interface. the software will import dxf dwg file, and i will estimate room area wall area and some object lengths with the help of cad windows in teh software, whhere should i start? i am writing on c# and for cad interface i know i need opengl, can you help me with that?

This probably doesn’t have anything to do with OpenGL. Presumably, the user sketches out a room/rooms in an existing CAD package, exports that data to some file, and then you read that in, compute areas from walls in the drawing/layout, and generating some cost estimates. How do you see OpenGL being involved?