Polygon clipping method based on intersection point sorting

Abstract

The invention discloses a polygon clipping method based on intersection point sorting. The polygon clipping method comprises steps including that 1, whether segments are intersected or not is judged according to opposite clipping positions of four intersection points of a clipped side, and in and out properties of the intersection points are analyzed, 2, a solid polygon is subjected to intersection by means of taking sides of a clipped polygon sequentially, whether final points of the clipped sides can form a result polygon or not is judged according to sequence and the in and out properties of the intersection points on each clipped side, vertexes of the clipped polygon forming the result polygon are inserted into an intersection point linked list, and accordingly a point pair consisting of an in point and an out point is formed, 3, pointer directions of all intersection points are set according to the in and out properties of the intersection points and a sequence number of a final point of the recorded solid polygon, vertexes of the solid polygon forming the result polygon are inserted into the intersection point linked list, and secondary sorting of the intersection points is completed, and 4, a result vortex linked list is traversed, and the result polygon is outputted according to the pointer directions. The polygon clipping method has important actual application values in the field of computer graphics.

Description

technical field [0001] The invention relates to the technical field of polygon clipping in computer graphics, in particular to a polygon clipping method based on intersection sorting. Background technique [0002] Cropping is a fundamental operation in graphics. Classical polygon clipping algorithms, such as Sutherland-Hodgeman algorithm, beam-Barsky algorithm, etc., require clipping polygons to be rectangles, but in practical applications, clipping polygons and solid polygons may be general polygons and contain inner rings. Weiler algorithm, Vatti algorithm, and Greiner-Hormann algorithm can process the clipping of general polygons within a certain period of time. Among them, the Weiler algorithm uses a tree data structure, and the Vatti and Greiner-Hormann algorithms use a bilinear linked list data structure. After improving the above three algorithms, Liu Yongkui and others proposed a new polygon clipping algorithm (Liu's algorithm), which optimized the original data str...

AI Technical Summary

Problems solved by technology

However, the intersection point of the algorithm adopts a double-pointer structure. Inserting the intersection point into the solid polygon and clipping the polygon vertex list makes the number of sides participating in the intersection increase due to the increase in the number of polygon vertices, resulting in redundancy in the algorithm. When the number of polygon intersection points When the number is increasing, the impact of repeated intersection calculations on the efficiency of the algorithm is more obvious

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