Recall from Section 1 of compositePieIndicators.pl that the location of the text is defined as the first set of polygon coordinates on a line from the triangle.vertices file.

回想一下 compositePieIndicators.pl 的第 1 部分，文本的位置被定义为 triangle.vertices 文件中某一行的第一组多边形坐标。

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Triangles are popular with 3d implementations because you can define any polygon as a set of triangles.

任何多边形都可定义为一组三角形的集合，因此三角形在3d实现中应用十分广泛。

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In order to prevent us from drawing one poly more than one time we should have a flag on each polygon which will be set if the poly is drawn for the first time.

为了防止重画一个多边形，我们应当在每一个多边形上做一个标记，当多边形第一次被画的时候，设置这个标记当然画之前也要检查这个标记啦，不过肯定影响效率。

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Sol 1, as the days are known on Mars, was a busy time for the three-legged lander, which set down Sunday in relatively flat terrain cut by polygon-shaped fissures.

NPR: Phoenix Sends Color Photos of Mars to NASA