In order to improve the raster conversion speed of circles, the characteristics of raster circles were analyzed, and a hybrid run-length algorithm for rapid circle drawing, mainly based on double-stepping in combination with detail mode analysis, was proposed. The double-stepping was adopted in the mode with larger horizontal run-length for raster circles. In addition, the mixed single and double stepping was adopted for the area with sharp curvature change as well as the run-length mode in the 45?direction. Furthermore, each horizontal run-length was controlled and output at one time. The characteristics of raster circles and the advantages of both multi-step algorithm and run-length algorithm were effectively included. Therefore, only about 2. 86 basic operations are needed for generating one point, and the I/O number substantially reduces. The experimental results show that the circle-drawing speed of the proposed algorithm is significantly superior to that of the existing other algorithms. The average circle-drawing speed of the proposed algorithm is twice more than that of the classical Bresenham algorithm. Moreover, the proposed algorithm can be extended to the drawing of ellipse and other conic curves.%为了提高圆弧的光栅转换速度,分析了光栅圆弧的特性,提出了一种以2点步进为主、结合细节模式分析的快速绘制圆弧的混合行程算法.该算法在光栅圆弧水平行程较长的模式采用2点步进,在曲率变化剧烈的区域和45°方向的行程模式采用单点和2点混合步进,并控制所有水平行程一次性输出,有效利用了光栅圆弧的特性和多步法及行程算法的优势,使得平均每生成一点仅消耗约2.86次基本运算,大幅度减少了I/O次数.实验和分析结果表明,新算法的圆弧速度明显优于现有其他算法,其平均圆弧绘制速度较经典Brcscnham算法提高1倍以上,且可推广到椭圆或其他二次曲线的绘制中.
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