Liang-Barsky线段裁剪算法python

Liang-Barsky线段裁剪算法是一种经典的计算机图形学算法，用于在二维空间中高效地判断两条或多条线段是否相交。Python实现这个算法的关键在于理解其数学原理，并编写循环来处理每一对线段的交点检查。

该算法基于四个条件（边界、左端点、右端点和斜率），通过逐次比较这些条件来确定两条线段是否相交。以下是算法的一个简化版Python实现：

def liang_barsky(a1, b1, a2, b2):
    # 线段参数：(x1, y1), (x2, y2)
    direction = ((b2[0] - a2[0]) * (a1[1] - b1[1])) > ((a2[1] - b2[1]) * (a1[0] - b1[0]))
    
    t_max, t_min = float('-inf'), float('inf')
    if direction:
        x_diff = b1[0] - a1[0]
        y_diff = b1[1] - a1[1]
        u_max = min((a2[0] - a1[0]) / x_diff, (a2[1] - a1[1]) / y_diff) if x_diff != 0 else float('inf')
        u_min = max((b2[0] - a1[0]) / x_diff, (b2[1] - a1[1]) / y_diff) if x_diff != 0 else float('-inf')
    else:
        x_diff = b1[0] - a1[0]
        y_diff = b1[1] - a1[1]
        v_max = min((a2[0] - a1[0]) / x_diff, (a2[1] - a1[1]) / y_diff) if x_diff != 0 else float('inf')
        v_min = max((b2[0] - a1[0]) / x_diff, (b2[1] - a1[1]) / y_diff) if x_diff != 0 else float('-inf')
        
    t = [u_min, v_min, u_max, v_max]
    for ti in t:
        if ti >= 0 and ti <= 1:
            return True

    return False

# 示例用法
line1 = [(0, 0), (5, 5)]
line2 = [(2, 2), (8, 8)]
if liang_barsky(line1, line2):
    print("两条线段相交")
else:
    print("两条线段不相交")