24. Frustum clipping (clip space)

• When vertex shader writes into gl_Position, the resulting coordinate is considered to be in clip space. What this means is that the vertex becomes a subject for clipping.

• Thus, OpenGL clipping takes place in clip space as follows:

  • Any geometrical primitives outside the top, bottom, left and right of the view volume cube are clipped.

  • Anything in front near plane or behind the far plane is discarded:

    • if a triangle has at least one vertex in front or behind the view volume, the entire triangle is removed from the view.