Abstract: An occlusion culling circuit for use in a graphics computer receives graphics primitives data including x and y coordinates for each pixel, a z depth value, and r, g, b, and a or index color data. For each group of primitives, the graphics computer scans the primitive and determines a volume which completely bounds the primitive. The z depth values for the pixels comprising the bounding volume are then compared by the occlusion culling circuit to the depths of the pixels in the already rendered primitives to determine whether any pixels in the incoming primitive are visible. If no pixels are visible, the occlusion culling circuit clears the result register and receives the next graphics primitive. If, on the other hand, one or more pixels is visible, the occlusion culling circuit completely renders the primitives bounded by the bounding volume.

Abstract: A solution to the problem of determining the degree of visibility for a bounding volume is to first sort the bounding volumes into an order in which they can be tested, after which they are rendered as if they were polygons in their own right. Prior to the testing of the next bounding volume a Bounding Volume Visibility (BVV) mode is enabled. This temporarily suspends write operations to the frame buffer and it resets a TOTAL PIXEL COUNTER and a VISIBLE PIXEL COUNTER. Then the polygon sides of the bounding volume are rendered, with each and every pixel of those polygons being checked for depth, as would be the pixels for "real" polygons. Each such pixel rendered causes an increment of the TOTAL PIXEL COUNTER, while each such pixel that meets the depth criteria in use causes an increment of the VISIBLE PIXEL COUNTER. The BVV mode is subsequently turned off, and the values of the two counters inspected. The inspecting entity may be software associated with the graphics application.

Abstract: An occlusion culling circuit for use in a graphics computer receives graphics primitives data including x and y coordinates for each pixel, a z depth value, and r, g, b, and a or index color data. For each group of primitives, the graphics computer scans the primitive and determines a volume which completely bounds the primitive. The z depth values for the pixels comprising the bounding volume are then compared by the occlusion culling circuit to the depths of the pixels in the already rendered primitives to determine whether any pixels in the incoming primitive are visible. If no pixels are visible, the occlusion culling circuit clears the result register and receives the next graphics primitive. If, on the other hand, one or more pixels is visible, the occlusion culling circuit completely renders the primitives bounded by the bounding volume.