Source Code for Module visgraph.drawing.bezier

 1   
 2 -def splitline(pt1, pt2, percent=0.5): 
 3      ''' 
 4      Return a point which splits the given line at the 
 5      given percentage... 
 6   
 7      Example: splitline( (0,0), (20, 30), 0.1) 
 8      ''' 
 9   
10      pt1_x, pt1_y = pt1 
11      pt2_x, pt2_y = pt2 
12   
13      deltax = (pt2_x - pt1_x) * percent 
14      deltay = (pt2_y - pt1_y) * percent 
15   
16      return int(pt1_x + deltax), int(pt1_y + deltay) 
17   
18 -def calculate_bezier(points, steps = 30): 
19      ''' 
20      Arbitrary depth and arbitrary precision bezier implementation.  Takes 
21      a list of (x,y) point tuples and returnes the points to draw for the 
22      bezier curve. 
23      ''' 
24      ret = [] 
25      points = [ (float(x),float(y)) for x,y in points ] 
26   
27      for i in xrange(steps+1): 
28   
29          pcent = i / float(steps) 
30   
31          layers = [ points, ] 
32          while len(layers[-1]) != 1: 
33              l_points = layers[-1] 
34              newpoints = [ splitline( l_points[i], l_points[i+1], pcent) for i in xrange(len(l_points)-1) ] 
35              layers.append(newpoints) 
36   
37          ret.append(layers[-1][0]) 
38   
39      return ret 
40   
41  if __name__ == '__main__': 
42      print calculate_bezier( [ (0,0), (3, 20), (20, 23), (20, 20)] ) 
43   
44      print calculate_bezier( [ (0,0), (10,10) ], 10) 
45