角和矩形的交点

import math

import matplotlib.pyplot as plt


def calc_theta(point1, point2):
    delta_x = point2[0] - point1[0]
    delta_y = point2[1] - point1[1]
    if delta_x > 0:  # 第一第四象限，直接用反正切函数
        return math.atan(delta_y / delta_x)
    elif delta_x == 0 and delta_y > 0:
        return math.pi / 2
    elif delta_x == 0 and delta_y < 0:
        return -math.pi / 2
    elif delta_y >= 0:
        return math.atan(delta_y / delta_x) + math.pi
    else:
        return math.atan(delta_y / delta_x) - math.pi


def calc_cross(bbox, center, theta1, theta2):
    [xmin, ymin, xmax, ymax] = bbox
    [x, y] = center
    up_right_theta = calc_theta(center, [xmax, ymax])
    up_left_theta = calc_theta(center, [xmin, ymax])
    down_right_theta = calc_theta(center, [xmax, ymin])
    down_left_theta = calc_theta(center, [xmin, ymin])
    # 第一个交点
    if down_right_theta < theta1 < up_right_theta:  # 和(xmax,?)相交，(?-y)/(xmax-x)=tan(theta1)
        cross_point1 = [xmax, math.tan(theta1) * (xmax - x) + y]
        cross_flag1 = 0  # 和x=xmax相交
    elif up_right_theta <= theta1 <= up_left_theta:  # 和(?,ymax)相交，(ymax-y)/(?-x)=tan(theta1)
        cross_point1 = [(ymax - y) / math.tan(theta1) + x, ymax]
        cross_flag1 = 1  # 和y=ymax相交
    elif down_left_theta <= theta1 <= down_right_theta:  # 和(?,ymin)相交，(ymin-y)/(?-x)=tan(theta1)
        cross_point1 = [(ymin - y) / math.tan(theta1) + x, ymin]
        cross_flag1 = 3  # 和y=ymin相交
    else:  # 和(xmin,?)相交，(?-y)/(xmin-x)=tan(theta1)
        cross_point1 = [xmin, math.tan(theta1) * (xmin - x) + y]
        cross_flag1 = 2  # 和x=xmin相交
    # 第二个交点
    if down_right_theta < theta2 < up_right_theta:  # 和(xmax,?)相交，(?-y)/(xmax-x)=tan(theta1)
        cross_point2 = [xmax, math.tan(theta2) * (xmax - x) + y]
        cross_flag2 = 0
    elif up_right_theta <= theta2 <= up_left_theta:  # 和(?,ymax)相交，(ymax-y)/(?-x)=tan(theta1)
        cross_point2 = [(ymax - y) / math.tan(theta2) + x, ymax]
        cross_flag2 = 1
    elif down_left_theta <= theta2 <= down_right_theta:  # 和(?,ymin)相交，(ymin-y)/(?-x)=tan(theta1)
        cross_point2 = [(ymin - y) / math.tan(theta2) + x, ymin]
        cross_flag2 = 3
    else:  # 和(xmin,?)相交，(?-y)/(xmin-x)=tan(theta1)
        cross_point2 = [xmin, math.tan(theta2) * (xmin - x) + y]
        cross_flag2 = 2

    return {"points": [cross_point1, cross_point2], "flag": [cross_flag1, cross_flag2]}


def make_polygon(bbox, center, cross_point, cross_flag):
    [xmin, ymin, xmax, ymax] = bbox
    cross_point1 = cross_point[0]
    cross_point2 = cross_point[1]
    cross_flag1 = cross_flag[0]  #
    cross_flag2 = cross_flag[1]

    if cross_flag1 == 0 and cross_flag2 == 0:
        if cross_point1[1] < cross_point2[1]:
            point_list = [center, cross_point1, cross_point2]
        else:
            point_list = [center, cross_point1, [xmax, ymax], [xmin, ymax], [xmin, ymin], [xmax, ymin], cross_point2]
    elif cross_flag1 == 0 and cross_flag2 == 1:
        point_list = [center, cross_point1, [xmax, ymax], cross_point2]
    elif cross_flag1 == 0 and cross_flag2 == 2:
        point_list = [center, cross_point1, [xmax, ymax], [xmin, ymax], cross_point2]
    elif cross_flag1 == 0 and cross_flag2 == 3:
        point_list = [center, cross_point1, [xmax, ymax], [xmin, ymax], [xmin, ymin], cross_point2]

    elif cross_flag1 == 1 and cross_flag2 == 0:
        point_list = [center, cross_point1, [xmin, ymax], [xmin, ymin], [xmax, ymin], cross_point2]
    elif cross_flag1 == 1 and cross_flag2 == 1:
        if cross_point1[0] > cross_point2[0]:
            point_list = [center, cross_point1, cross_point2]
        else:
            point_list = [center, cross_point1, [xmin, ymax], [xmin, ymin], [xmax, ymin], [xmax, ymax], cross_point2]
    elif cross_flag1 == 1 and cross_flag2 == 2:
        point_list = [center, cross_point1, [xmin, ymax], cross_point2]
    elif cross_flag1 == 1 and cross_flag2 == 3:
        point_list = [center, cross_point1, [xmin, ymax], [xmin, ymin], cross_point2]

    elif cross_flag1 == 2 and cross_flag2 == 0:
        point_list = [center, cross_point1, [xmin, ymin], [xmax, ymin], cross_point2]
    elif cross_flag1 == 2 and cross_flag2 == 1:
        point_list = [center, cross_point1, [xmin, ymin], [xmax, ymin], [xmax, ymax], cross_point2]
    elif cross_flag1 == 2 and cross_flag2 == 2:
        if cross_point1[1] > cross_point2[1]:
            point_list = [center, cross_point1, cross_point2]
        else:
            point_list = [center, cross_point1, [xmin, ymin], [xmax, ymin], [xmax, ymax], [xmin, ymax], cross_point2]
    elif cross_flag1 == 2 and cross_flag2 == 3:
        point_list = [center, cross_point1, [xmin, ymin], cross_point2]

    elif cross_flag1 == 3 and cross_flag2 == 0:
        point_list = [center, cross_point1, [xmax, ymin], cross_point2]
    elif cross_flag1 == 3 and cross_flag2 == 1:
        point_list = [center, cross_point1, [xmax, ymin], [xmax, ymax], cross_point2]
    elif cross_flag1 == 3 and cross_flag2 == 2:
        point_list = [center, cross_point1, [xmax, ymin], [xmax, ymax], [xmin, ymax], cross_point2]
    else:
        if cross_point1[0] < cross_point2[0]:
            point_list = [center, cross_point1, cross_point2]
        else:
            point_list = [center, cross_point1, [xmax, ymin], [xmax, ymax], [xmin, ymax], [xmin, ymin], cross_point2]

    return point_list

def angle_intersect_rectangle(bbox,center,theta1,theta2):
    dic=calc_cross(bbox,center,theta1,theta2)
    cross_point=dic["points"]
    cross_flag=dic["flag"]
    return make_polygon(bbox,center,cross_point,cross_flag)

while 1:
    # bbox=[xmin,ymin,xmax,ymax]
    bbox = eval(input("输入bbox:"))
    [xmin, ymin, xmax, ymax] = bbox
    # center=[xc,yc]
    center = eval(input("输入center:"))

    th1 = eval(input("输入角度1："))
    th2 = eval(input("输入角度2："))

    theta1 = th1 / 180 * math.pi
    theta2 = th2 / 180 * math.pi



    point_list =angle_intersect_rectangle(bbox, center,theta1, theta2)

    x = []
    y = []
    for p in point_list:
        x.append(p[0])
        y.append(p[1])

    x.append(point_list[0][0])
    y.append(point_list[0][1])



    plt.figure(num=3, figsize=(8, 5))
    plt.plot([xmax, xmin, xmin, xmax, xmax], [ymax, ymax, ymin, ymin, ymax], color="red")
    plt.plot(x, y, color="yellow")
    plt.show()

上述代码可稍作修改将矩形也画出，便于观察。下面是几个实验结果：

本文地址：https://blog.csdn.net/qq_40268672/article/details/107674760