Method and apparatus for reducing illumination calculations through efficient visibility determination

摘要

A computer graphics system reduces the number of lighting calculations required to render a scene having objects illuminated by light sources by classifying each primitive for objects in an illuminated scene as either hidden or visible using a z-buffer. In a first approach, only one pass is made through the display list of primitives for the scene, and lighting calculations are performed only for primitives classified as visible. In a second approach, two passes are made through the display list. In the first pass, the display list is fully traversed to set-up the z-buffer, and no lighting calculations are performed. When the second pass of the display list is performed, each primitive is classified as hidden or visible, and lighting calculations are performed for each primitive classified as visible as the display list is traversed. Lighting calculations may be performed using either Gouraud or Phong shading.