A system, method and computer program product are provided for avoiding reading
z-values in a graphics pipeline. Initially, near z-values are stored which are
each representative of a near z-value on an object in a region. Such region is
defined by a tile and a coverage mask therein. Thereafter, the stored near z-values
are compared with far z-values computed for other objects in the region. Such comparison
indicates whether an object is visible in the region. Based on the comparison,
z-values previously stored for image samples in the region are conditionally read
from memory.
