How to check if an object lies outside the clipping volume in OpenGL?

Question

I\'m really confused about OpenGL\'s modelview transformation. I understand all the transformation processes, but when it comes to projection matrix, I\'m lost :(

If

Answer 1

For anyone relying on the accepted answer, it is incorrect (at least in current implementations). OpenGL clips in the z plane the same as the x and y as -w < z < w (https://www.khronos.org/opengl/wiki/Vertex_Post-Processing).

The two tests for z should then be: std::abs(Pclip.z) < Pclip.w

Checking for zero will exclude all the drawn points that are closer to the near field clip plane than the far field clip plane.