I try smth like this:

def main_rec():
    width = random.randint(150, 250)
    height = random.randint(150, 250)
    angle = rand_angle()
    c, s = np.cos(angle), np.sin(angle)
    R = np.array(((c, -s), (s, c)))

    center = (random.randint(0, 640), random.randint(0, 480))
    x1y10 = (center[0] - width / 2, center[1]   height / 2)
    x2y20 = (x1y10[0]   width, x1y10[1])
    x3y30 = (x2y20[0], x2y20[1] - height)
    x4y40 = (x3y30[0] - width, x3y30[1])
    x1y1 = (x1y10[0] * R[0][0]   x1y10[1] * R[0][1], x1y10[0] * R[1][0]   x1y10[1] * R[1][1])
    x2y2 = (x2y20[0] * R[0][0]   x2y20[1] * R[0][1], x1y10[1] * R[0][1]   x2y20[1] * R[1][1])
    x3y3 = (x3y30[0] * R[0][0]   x3y30[1] * R[0][1], x3y30[0] * R[1][0]   x3y30[1] * R[1][1])
    x4y4 = (x4y40[0] * R[0][0]   x4y40[1] * R[0][1], x4y40[1] * R[0][1]   x4y40[1] * R[1][1])

    points = [x1y1, x2y2, x3y3, x4y4]
    return points, angle / 3.14159 * 180

but I don't know how to set a condition for the corners to be right. I try to use rotation matrix. It makes normal rectangles only for angle = 0

CodePudding user response：

using numpy and rotation matrix code would be:

import numpy as np
import matplotlib.pyplot as plt

def create_rect(width,height,center):
    x,y = center
    w,h = width,height
    return np.array([[x-w/2,y-h/2],
                     [x w/2,y-h/2],
                     [x w/2,y h/2],
                     [x-w/2,y h/2],
                     [x-w/2,y-h/2]]).T

width = np.random.randint(150,250)
height = np.random.randint(150,250)
center = (np.random.randint(0, 640), np.random.randint(0, 480))

angle = np.random.randint(0,360)/360.0*2*np.pi
rotmat = np.array([[np.cos(angle),-np.sin(angle)],
                   [np.sin(angle),np.cos(angle)]])


rect = create_rect(width,height,center)

rot_rect = rotmat @ rect

plt.imshow(*rot_rect)