参考资料：Python-OpenCV——绘图（画线，矩形，圆，加文字）_zangba9624的博客-CSDN博客

示例代码

# -*- coding:utf-8 -*-
import cv2
import numpy as np
 
img = cv2.imread("1.jpg", 1)
pts = np.array([[10, 10], [400, 10], [400, 400], [10, 400]], np.int32)  # 数据类型必须为 int32
pts = pts.reshape((-1, 1, 2))

# 绘制未填充的多边形
cv2.polylines(img, [pts], isClosed=True, color=(0,0,255), thickness=1)

# 绘制填充的多边形
# cv2.fillPoly(img, [pts], color=(255, 255, 0))
cv2.imshow('img', img)
cv2.waitKey()