| 摘要 |
Objects are represented in a coordinate space which is twice scanned by scan lines, once in one direction and then once in another direction. At each scan line, a list of line segments is generated, where each line segment represents the intersection of the projection of a polygon and the scan line. The segments are then examined to determine which are visible segments, using the z values of the end points of the segments. The visible segments of a scan line are compared to the visible segments of a previous scan line or an accumulation of visible lines, and if the end points of a visible segment taken from a polygon differ by less than a threshold amount, the lines formed between end points in one scan line and the adjacent scan line are considered to be visible lines. Where the two scans are a horizontal scan and a vertical scan, the threshold amount for vertical scans is the distance between horizontal scans and the threshold amount for horizontal scans is the distance between vertical scans. <IMAGE>
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