本算法的直线穿越过程通过先找到任何一个与直线相交的三角形(多数情况下是最左边的一个)，再分别向两边穿越， 最终找出所有经过的三角形。-A straight line through the process of this algorithm to find any one by first intersected triangle (in most cases is the leftmost one), and then were to both sides through the end