| 摘要 |
When rendering a three-dimensional image, which is modeled from interconnected polygons, on a display area, a visibility preprocessor determines a visibility status for each of the polygons that can be projected onto a projection plane of a selected part of the display area. Based on the visibility status of the polygons, a Coarse-Z testing circuit can skip those polygons that are concluded to be hidden, and performs a Coarse-Z test for those polygons that are not concluded to be hidden. A graphics rendering circuit is controlled by the Coarse-Z testing circuit to render the polygons, which are concluded to be currently and completely visible during the Coarse-Z test thereof. A Z-testing circuit is controlled by the Coarse-Z testing circuit to perform a Z-test for those polygons whose status is indeterminate, and controls the graphics rendering circuit so as to render points which are concluded to be visible during the Z-test.
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