Nicholl-Lee-Nicholl线段裁剪算法的python代码

Nicholl-Lee-Nicholl (NLL) 线段裁剪算法是一种用于处理空间分割问题的有效技术，主要用于地图制图、计算机图形学等领域。它通过减少冗余计算来优化线段之间的相交检查。以下是简单的Python代码示例，采用了递归的方式实现：

def nll_line_segment_intersection(line1, line2):
    # 线段表示为两个点(x1, y1), (x2, y2)
    x1, y1 = line1[0]
    x2, y2 = line1[1]
    a1, b1 = (y2 - y1), (x1 - x2)

    x3, y3 = line2[0]
    x4, y4 = line2[1]
    a2, b2 = (y4 - y3), (x3 - x4)

    # 计算交叉矩阵
    det = a1 * b2 - a2 * b1

    if det == 0:  # 并行
        return None

    t1 = ((a2 * (x1 - x3)) + (b2 * (y1 - y3))) / det
    t2 = ((a1 * (x1 - x3)) + (b1 * (y1 - y3))) / det

    if 0 <= t1 <= 1 and 0 <= t2 <= 1:  # 区间内
        return [(x1 + t1 * (x2 - x1), y1 + t1 * (y2 - y1))]
    elif t1 < 0 or t2 < 0:  # 线段外
        return []
    else:  # 相交
        return nll_line_segment_intersection((x1, y1), (x1 + t1 * (x2 - x1), y1 + t1 * (y2 - y1))) + \
               nll_line_segment_intersection((x1 + t1 * (x2 - x1), y1 + t1 * (y2 - y1)), (x2, y2))

# 使用示例
line1 = [(0, 0), (10, 10)]
line2 = [(5, 5), (15, 15)]
intersection_points = nll_line_segment_intersection(line1, line2)
if intersection_points:
    print("Intersection points:", intersection_points)
else:
    print("No intersection.")