ABSTRACT
This chapter presents how to derive a secondary texture from a normal depth-only shadow map. Hierarchical min/max shadow maps were introduced in order to quickly (hierarchically) reject or accept sub-blocks in a shadow filter footprint that are in full light or in full shadow. Walking the min/max shadow hierarchy does add to the texturing cost. The plane equation is stored if the block of shadow map pixels that is considered for constructing one min/max pixel lies within a plane. The plane equation allows to decide if a pixel is in front or behind a plane and does not suffer from the need for a high depth bias. Because T stores min/max depth or a plane equation it can be called a hybrid min/max plane shadow map (HPSM). The chapter discusses how to construct an HPSM, how to use the HPSM to quickly reject expensive filter operations, and other uses for HPSMs.
