Point in frustum in Ortho projection mode

OpenGL OpenGL: Basic Coding
1

Hi All,

We’ve found this lovely tutorial on how to test if a point is inside a perspective frustum:

http://www.lighthouse3d.com/opengl/viewfrustum/index.php?clipspaceimp

What about orthographic one? Is there a way to extract it in the same way from A = M*P matrix?

Thanks,

Alberto