liang-barsky算法Python

以下是 Liang-Barsky 算法的 Python 实现：

def liang_barsky(x1, y1, x2, y2, xmin, ymin, xmax, ymax):
    dx = x2 - x1
    dy = y2 - y1
    p1 = -dx
    p2 = dx
    p3 = -dy
    p4 = dy
    q1 = x1 - xmin
    q2 = xmax - x1
    q3 = y1 - ymin
    q4 = ymax - y1

    posarr = [1]
    negarr = [0]
    posind = 1
    negind = 1

    if p1 == 0 and q1 < 0 or p3 == 0 and q3 < 0:
        print("Line is outside the clipping window")
        return

    if p1 != 0:
        r1 = q1 / p1
        r2 = q2 / p2
        if p1 < 0:
            negarr.append(r1)
            posarr.append(r2)
            negind += 1
            posind += 1
        else:
            negarr.append(r2)
            posarr.append(r1)
            negind += 1
            posind += 1

    if p3 != 0:
        r3 = q3 / p3
        r4 = q4 / p4
        if p3 < 0:
            negarr.append(r3)
            posarr.append(r4)
            negind += 1
            posind += 1
        else:
            negarr.append(r4)
            posarr.append(r3)
            negind += 1
            posind += 1

    xn1 = 0
    yn1 = 0
    xn2 = 0
    yn2 = 0
    rn1 = 0
    rn2 = 1

    for i in range(1, posind):
        rn = posarr[i]
        if rn < rn2:
            rn2 = rn

    for i in range(1, negind):
        rn = negarr[i]
        if rn > rn1:
            rn1 = rn

    xn1 = x1 + rn1 * dx
    yn1 = y1 + rn1 * dy
    xn2 = x1 + rn2 * dx
    yn2 = y1 + rn2 * dy

    print("The coordinates of the clipped line are: ({:.2f}, {:.2f}) and ({:.2f}, {:.2f})".format(xn1, yn1, xn2, yn2))

这个程序假设输入的线段的起点和终点坐标分别为 (x1, y1) 和 (x2, y2)，裁剪窗口的四个边界坐标分别为 xmin, ymin, xmax 和 ymax。函数 `liang_barsky` 的输出为经过裁剪后的线段的两个端点的坐标。