python掃描線填充算法詳解

更新時間：2020年02月19日 13:18:49 作者：油醋三椒

這篇文章主要為大家詳細介紹了python掃描線填充算法，文中示例代碼介紹的非常詳細，具有一定的參考價值，感興趣的小伙伴們可以參考一下

本文實例為大家分享了python掃描線填充算法，供大家參考，具體內(nèi)容如下

介紹

1.用水平掃描線從上到下掃描由點線段構(gòu)成的多段構(gòu)成的多邊形。

2.每根掃描線與多邊形各邊產(chǎn)生一系列交點。將這些交點按照x坐標進行分類，將分類后的交點成對取出，作為兩個端點，以所填的色彩畫水平直線。

3.多邊形被掃描完畢后，填色也就完成。

數(shù)據(jù)結(jié)構(gòu)

活性邊表：

新邊表：

代碼（使用數(shù)組）

import numpy as np
from PIL import Image
from PIL import ImageDraw
from PIL import ImageFont
 
array = np.ndarray((660, 660, 3), np.uint8)
array[:, :, 0] = 255
array[:, :, 1] = 255
array[:, :, 2] = 255
 
for i in range(0,660,1):
 array[i,330]=(0,0,0)
for j in range(0,660,1):
 array[330,j]=(0,0,0)
 
 
def creat_Net(point, row, y_min,y_max ): 
 Net = [([ ] * y_max ) for i in range(y_max )] 
 point_count = point.shape[0]
 for j in range(0, point_count): 
 x = np.zeros(10) 
 first = int(min(point[(j+1)%point_count][1] , point[j][1])) 
 x[1] = 1/((point[(j+1)%point_count][1]-point[j][1])/(point[(j+1)%point_count][0]-point[j][0])) # x 的增量
 x[2] = max(point[(j+1)%point_count][1] , point[j][1]) 
 if(point[(j+1)%point_count][1] < point[j][1]):
  x[0] = point[(j+1)%point_count][0] 
 else:
  x[0] = point[j][0] 
 Net[first].append(x) 
 return Net

def draw_line(i,x ,y ):
 for j in range(int(x),int(y)+1):
 array[330-i,j+330]=(20,20,20)
 

def polygon_fill(point):
 y_min = np.min(point[:,1])
 y_max = np.max(point[:,1]) 
 Net = creat_Net(point, y_max - y_min + 1, y_min, y_max) 
 x_sort = [] * 3
 for i in range(y_min, y_max): 
 x = Net[i]
 if(len(x) != 0): 
  for k in x :
  x_sort.append(k) 
 x_image = [] * 3 
 for cell in x_sort:
  x_image.append(cell[0])
 x_image.sort()
 if(len(x_image) >= 3 and x_image[0]==x_image[1] and x_image[2]>x_image[1]):
  x_image[1] = x_image[2] 
 draw_line(i, x_image[0], x_image[1])
 
 linshi = [] * 3 
 for cell in x_sort:
  if cell[2] > i: 
  cell[0] += cell[1]
  linshi.append(cell)  
 x_sort = linshi[:] 

 x_image = [] * 3 
 for cell in x_sort:
 x_image.append(cell[0])
 x_image.sort()
 
 draw_line(i, x_image[0],x_image[1]) 

def main(): 
 point = [[55,40], [100,80], [100,160],[55,180], [10,160], [10,80]]
 point = np.array(point) 
 polygon_fill( point )
 image = Image.fromarray(array)
 image.save('saomao.jpg')
 image.show() 

if __name__ == "__main__":
 main()

實例：