How to Find a point in cuboid using open gl

i am using open gl with visual studio and visual c++.I want to find a point of cube that lie开发者_Go百科 inside or outside.

@Nicol Bolas already commented it, but I'll give this as answer:

OpenGL is not meant to be used for this. OpenGL is a rendering API, i.e. it is meant for drawing stuff. And although OpenGL-1 and OpenGL-2 have rudimentary matrix manipulation functions it is neither a linear math library nor a computational geometry system. It may be (actually is) possible to abuse OpenGL for this kind of thing, but that doesn't mean you should do it.

Or simply put: OpenGL doesn't do this kind of stuff. You can't (well, should not) do that using OpenGL.