On Windows, how does OpenGL differ from DirectX?

Question

I don\'t have any hands on experience with graphics programming. I got this doubt when I was reading about graphics programming.

From what I understand, because Wind

Answer 1

DirectX is a layer to use the hardware functions of the graphic card. Since Windows Vista, default OpenGL implementation (the one provided from Microsoft) uses DirectX, so OpenGL is really slow. However, graphic card manufacturers provides drivers with OpenGL using directly using the graphic card and not passing through directX, so performances should be the same. If you have an integrated graphic card with poor driver, OpenGL may uses DirectX.