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Contents of /fract/julia2.cgi

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Revision 1.1.1.1 - (show annotations) (vendor branch)
Sat Feb 24 15:57:15 2001 UTC (23 years, 1 month ago) by teddy
Branch: masse, MAIN
CVS Tags: start, HEAD
Changes since 1.1: +0 -0 lines
Imported sources (take 2)

1 #!/usr/bin/python
2
3 import cgi, Image, ImageDraw, sys
4 from string import atoi
5
6 form= cgi.FieldStorage()
7
8 maxiter= 270
9
10 width, height= 570, 570 # Image size
11 xmax, ymax = width-1, height-1 # Coordinate maximums
12
13 inx=max(0, min(atoi(form['image.x'].value), xmax))
14 iny=max(0, min(atoi(form['image.y'].value), ymax))
15
16 c1, c2 = (-2+2j), (2-2j) # Corner coordinates
17
18 # Force c1 to be upper left and c2 to be lower right
19 c1, c2= complex(min(c1.real, c2.real), max(c1.imag, c2.imag)), \
20 complex(max(c1.real, c2.real), min(c1.imag, c2.imag))
21
22 def constant(x, y):
23 creal= (float(x)/xmax)*(c2.real - c1.real)+c1.real
24 cimag= (float(y)/ymax)*(c2.imag - c1.imag)+c1.imag
25 return complex(creal, cimag)
26
27 c= constant(inx, iny) # Julia set coordinate
28
29 debug= 0
30
31 julia= Image.new("L", (width, height))
32 draw= ImageDraw.Draw(julia)
33
34 def drawrect((x1, y1), (x2, y2)):
35 color= plot(x1, y1)
36 cut= 0
37 x, y= x1+1, y1
38 while x<=x2:
39 if color<>plot(x, y):
40 cut= 1
41 x= x+1
42 x, y= x2, y1+1
43 while y<=y2:
44 if color<>plot(x, y):
45 cut= 1
46 y= y+1
47 x, y= x2-1, y2
48 while x>=x1:
49 if color<>plot(x, y):
50 cut= 1
51 x= x-1
52 x, y= x1, y2-1
53 while y>y1:
54 if color<>plot(x, y):
55 cut= 1
56 y= y-1
57 if x2-x1<=1 or y2-y1<=1:
58 return
59 if cut:
60 xc= ((x2-x1)/2)+x1
61 yc= ((y2-y1)/2)+y1
62 drawrect((x1+1, y1+1), (xc, yc)) # upper left
63 drawrect((xc+1, y1+1), (x2-1, yc)) # upper right
64 drawrect((x1+1, yc+1), (xc, y2-1)) # lower left
65 drawrect((xc+1, yc+1), (x2-1, y2-1)) # lower right
66 else:
67 if not debug:
68 draw.rectangle([x1+1, y1+1, x2-1, y2-1], fill= color)
69 if yorig >= 0: # The x axis is visible on image
70 # mirror over yorig, but keep within image
71 y1m= max(0, min(2*yorig-(y1+1), ymax))
72 y2m= max(0, min(2*yorig-(y2-1), ymax))
73 x1m= max(0, min(2*xorig-(x1+1), xmax))
74 x2m= max(0, min(2*xorig-(x2-1), xmax))
75 draw.rectangle([x1m, y1m, x2m, y2m], fill= color)
76
77 def plot(x, y):
78 z= constant(x, y)
79 i= 0
80 while i<maxiter and abs(z)<2:
81 z= z**2+c
82 i= i+1
83 color= 16*i%256
84 if i>=maxiter:
85 if debug:
86 color= 255
87 else:
88 color= 0
89 try:
90 julia.putpixel((x, y), color)
91 if yorig >= 0: # The x axis is visible on image
92 ym= 2*yorig-y # ym is y mirrored over yorig
93 xm= 2*xorig-x
94 if ym >= 0 and ym <= ymax and xm>=0 and xm<=xmax:
95 # ym is on the image
96 julia.putpixel((xm, ym), color)
97 except IndexError, the_error:
98 print "coord", x, y, xm, ym
99 raise IndexError, the_error
100 return color
101
102 # Initial default values
103 yfrom= 0
104 yto= ymax
105 yorig= -1 # The pixel coordinate of the x axis; negative means not on image
106 xorig= -1
107
108 # Check if we should do mirroring
109 if c1.imag > 0 and c2.imag < 0: # the x axis is visible
110 yorig= int((-c1.imag/(c2.imag-c1.imag))*height) # pixel pos. of x axis
111 if c1.imag < abs(c2.imag): # the x axis is closer to top than bottom
112 yfrom= yorig # Begin at x axis
113 else:
114 yto= yorig # End at x axis
115
116 if c1.real < 0 and c2.real > 0:
117 xorig= int((-c1.real/(c2.real-c1.real))*height)
118
119 drawrect((0, yfrom), (xmax, yto))
120
121 print "Content-type: image/png"
122 print
123 julia.save(sys.stdout, "PNG")

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