| 摘要 |
A method and apparatus for generating depth values in a programmable graphics system. Depth values are calculated under control of a pixel program using a variety of sources as inputs to programmable computation units (PCUs) in the programmable graphics systems. The PCUs are used to compute traditional interpolated depth values and modified depth values. Th PCUs are also used to compute arbitrary depth values which, unlike traditional interpolated depth values and modified depth values, are not dependent on the coordinates of the geometry primitive with which the arbitrary depth values are associated. Several sources are available as inputs to the PCUs. Clipping with optional clamping is performed using either interpolated depth values or calculated depth values, where calculated depth values are arbitrary depth values or modified depth values. Final depth values, used for depth testing, are selected from interpolated depth values and arbitrary depth values after clipping is performed.
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