- Vertex Specification - Vertex Processing - Vertex Post-
Processing - Primitive Assembly - Fragment Shader - Per-Sample
Processing Vertex Post-Processing is the stage in the OpenGL
Rendering Pipeline where the vertex outputs of the Vertex
Processing undergo a variety of operations. Many of these are
setup for Primitive Assembly and Rasterization stages.
Primitives generated by previous stages are collected and then
clipped to the view volume. Each vertex has a clip-space
position (the gl_Position output of the last Vertex Processing
stage). The viewing volume for a vertex is defined by: This
volume can be modified by depth clamping as well as the addition
of user-defined clip-planes. The total volume that primitives
are clipped to, including user-defined clip planes, is the
clipping volume. The way primitives are clipped to this clipping
volume depends on the basic Primitive type: - Points are not
really "clipped". If a point is in any way outside of the
clipping volume, then the primitive is discarded (ie: n