多边形平滑算法-ChaikinSmoothing

 1 import math
 2 
 3 # visualisation
 4 import matplotlib.pyplot as plt
 5 import matplotlib.lines as lines
 6 # visualisation
 7 
 8 def Sum_points(P1, P2):
 9     x1, y1 = P1
10     x2, y2 = P2
11     return x1+x2, y1+y2
12 
13 def Multiply_point(multiplier, P):
14     x, y = P
15     return float(x)*float(multiplier), float(y)*float(multiplier)
16 
17 def Check_if_object_is_polygon(Cartesian_coords_list):
18     if Cartesian_coords_list[0] == Cartesian_coords_list[len(Cartesian_coords_list)-1]:
19         return True
20     else:
21         return False
22 
23 class Object():
24 
25     def __init__(self, Cartesian_coords_list):
26         self.Cartesian_coords_list = Cartesian_coords_list
27 
28     def Find_Q_point_position(self, P1, P2):
29         Summand1 = Multiply_point(float(3)/float(4), P1)
30         Summand2 = Multiply_point(float(1)/float(4), P2)
31         Q = Sum_points(Summand1, Summand2)
32         return Q
33 
34     def Find_R_point_position(self, P1, P2):
35         Summand1 = Multiply_point(float(1)/float(4), P1)
36         Summand2 = Multiply_point(float(3)/float(4), P2)
37         R = Sum_points(Summand1, Summand2)
38         return R
39 
40     def Smooth_by_Chaikin(self, number_of_refinements):
41         refinement = 1
42         copy_first_coord = Check_if_object_is_polygon(self.Cartesian_coords_list)
43         while refinement <= number_of_refinements:
44             self.New_cartesian_coords_list = []
45 
46             for num, tuple in enumerate(self.Cartesian_coords_list):
47                 if num+1 == len(self.Cartesian_coords_list):
48                     pass
49                 else:
50                     P1, P2 = (tuple, self.Cartesian_coords_list[num+1])
51                     Q = obj.Find_Q_point_position(P1, P2)
52                     R = obj.Find_R_point_position(P1, P2)
53                     self.New_cartesian_coords_list.append(Q)
54                     self.New_cartesian_coords_list.append(R)
55 
56             if copy_first_coord:
57                 self.New_cartesian_coords_list.append(self.New_cartesian_coords_list[0])
58 
59             self.Cartesian_coords_list = self.New_cartesian_coords_list
60             refinement += 1
61         return self.Cartesian_coords_list
62 
63 if __name__ == "__main__":
64     Cartesian_coords_list = [(1, 1),
65                              (1, 3),
66                              (4, 5),
67                              (5, 1),
68                              (2, 0.5),
69                              (1, 1),]
70 
71     obj = Object(Cartesian_coords_list)
72     Smoothed_obj = obj.Smooth_by_Chaikin(number_of_refinements=5)
73 
74     # visualisation
75     x1 = [i for i, j in Smoothed_obj]
76     y1 = [j for i, j in Smoothed_obj]
77     x2 = [i for i, j in Cartesian_coords_list]
78     y2 = [j for i, j in Cartesian_coords_list]
79     plt.plot(range(7), range(7), 'w', alpha=0.7)
80     myline = lines.Line2D(x1, y1, color='r')
81     mynewline = lines.Line2D(x2, y2, color='b')
82     plt.gca().add_artist(myline)
83     plt.gca().add_artist(mynewline)
84     plt.show()
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原文地址：https://www.cnblogs.com/jeshy/p/15114956.html