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Contents of /fract/julia3.cgi

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Revision 1.1.1.1 - (show annotations) (vendor branch)
Sat Feb 24 15:57:15 2001 UTC (23 years, 8 months ago) by teddy
Branch: masse
CVS Tags: start
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 width, height= 570, 570 # Image size
9 xmax, ymax = width-1, height-1 # Coordinate maximums
10
11 inx=max(0, min(atoi(form['image.x'].value), xmax))
12 iny=max(0, min(atoi(form['image.y'].value), ymax))
13 debug= form.has_key('debug')
14
15 if form.has_key('iter'):
16 maxiter=atoi(form['iter'].value)
17 else:
18 maxiter= 270
19
20 c1, c2 = (-2+2j), (2-2j) # Corner coordinates
21
22 # Force c1 to be upper left and c2 to be lower right
23 c1, c2= complex(min(c1.real, c2.real), max(c1.imag, c2.imag)), \
24 complex(max(c1.real, c2.real), min(c1.imag, c2.imag))
25
26 def constant(x, y):
27 creal= (float(x)/xmax)*(c2.real - c1.real)+c1.real
28 cimag= (float(y)/ymax)*(c2.imag - c1.imag)+c1.imag
29 return complex(creal, cimag)
30
31 c= constant(inx, iny) # Julia set coordinate
32
33 julia= Image.new("L", (width, height))
34 draw= ImageDraw.Draw(julia)
35
36 def drawrect((x1, y1), (x2, y2)):
37 color= plot(x1, y1)
38 cut= 0
39 x, y= x1+1, y1
40 while x<=x2:
41 if color<>plot(x, y):
42 cut= 1
43 x= x+1
44 x, y= x2, y1+1
45 while y<=y2:
46 if color<>plot(x, y):
47 cut= 1
48 y= y+1
49 x, y= x2-1, y2
50 while x>=x1:
51 if color<>plot(x, y):
52 cut= 1
53 x= x-1
54 x, y= x1, y2-1
55 while y>y1:
56 if color<>plot(x, y):
57 cut= 1
58 y= y-1
59 if x2-x1<=1 or y2-y1<=1:
60 return
61 if cut:
62 if x2-x1 > y2-y1: # If wider than high
63 xc= ((x2-x1)/2)+x1
64 drawrect((x1, y1), (xc, y2))
65 drawrect((xc, y1), (x2, y2))
66 else: # if higher than wide
67 yc= ((y2-y1)/2)+y1
68 drawrect((x1, y1), (x2, yc))
69 drawrect((x1, yc), (x2, y2))
70 else:
71 if not debug:
72 draw.rectangle([x1, y1, x2, y2], fill= color)
73 if yorig >= 0: # The x axis is visible on image
74 # mirror over yorig, but keep within image
75 y1m= max(0, min(2*yorig-y1, ymax))
76 y2m= max(0, min(2*yorig-y2, ymax))
77 x1m= max(0, min(2*xorig-x1, xmax))
78 x2m= max(0, min(2*xorig-x2, xmax))
79 draw.rectangle([x1m, y1m, x2m, y2m], fill= color)
80
81 def plot(x, y):
82 z= constant(x, y)
83 i= 0
84 color= julia.getpixel((x, y))
85 if color<>0:
86 return color
87 while i<maxiter and abs(z)<2:
88 z= z**2+c
89 i= i+1
90 color= 16*i%256
91 if i>=maxiter or color==0:
92 if debug:
93 color= 255
94 else:
95 color= 1
96 try:
97 julia.putpixel((x, y), color)
98 if yorig >= 0: # The x axis is visible on image
99 ym= 2*yorig-y # ym is y mirrored over yorig
100 xm= 2*xorig-x
101 if ym >= 0 and ym <= ymax and xm>=0 and xm<=xmax:
102 # ym is on the image
103 julia.putpixel((xm-1, ym), color)
104 except IndexError, the_error:
105 print "coord", x, y, xm, ym
106 raise IndexError, the_error
107 return color
108
109 # Initial default values
110 yfrom= 0
111 yto= ymax
112 yorig= -1 # The pixel coordinate of the x axis; negative means not on image
113 xorig= -1
114
115 # Check if we should do mirroring
116 if c1.imag > 0 and c2.imag < 0: # the x axis is visible
117 yorig= int((-c1.imag/(c2.imag-c1.imag))*height) # pixel pos. of x axis
118 if c1.imag < abs(c2.imag): # the x axis is closer to top than bottom
119 yfrom= yorig # Begin at x axis
120 else:
121 yto= yorig # End at x axis
122
123 if c1.real < 0 and c2.real > 0:
124 xorig= int((-c1.real/(c2.real-c1.real))*height)
125
126 drawrect((0, yfrom), (xmax, yto))
127
128 print "Content-type: image/png"
129 print
130 julia.save(sys.stdout, "PNG")

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