├── .gitignore
├── README.md
└── main.py


/.gitignore:
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1 | *.png
2 | *.jpg
3 | 
4 | 


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/README.md:
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1 | ## Field
2 | 
3 | Creating computer art by simulating charged particle field lines.
4 | 
5 | ![Sample](http://i.imgur.com/9DxjkoX.png)
6 | 


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/main.py:
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 1 | from math import hypot, atan2, sin, cos, pi, radians
 2 | import cairo
 3 | import colorsys
 4 | import random
 5 | 
 6 | class Model(object):
 7 |     def __init__(self):
 8 |         self.particles = []
 9 |     def add(self, x, y, m=1.0):
10 |         self.particles.append((x, y, m))
11 |     def test(self, x, y):
12 |         dx = 0
13 |         dy = 0
14 |         for px, py, pm in self.particles:
15 |             d = hypot(x - px, y - py)
16 |             angle = atan2(y - py, x - px)
17 |             dx += pm * cos(angle) / d
18 |             dy += pm * sin(angle) / d
19 |         angle = atan2(dy, dx) + pi / 2
20 |         dx = cos(angle)
21 |         dy = sin(angle)
22 |         return (dx, dy)
23 | 
24 | def points(sides):
25 |     x = 0.5
26 |     y = 0.5
27 |     rotation = 0
28 |     angle = 2 * pi / sides
29 |     rotation = rotation - pi / 2
30 |     angles = [angle * i + rotation for i in range(sides)]
31 |     d = 0.35
32 |     return [(x + cos(a) * d, y + sin(a) * d) for a in angles]
33 | 
34 | def draw_path(dc, model, scale, width, r, g, b):
35 |     n = 128
36 |     f = 1 / 1024.0
37 |     sx = random.random()
38 |     sy = random.random()
39 |     for m in [-1, 1]:
40 |         x, y = sx, sy
41 |         dc.move_to(x, y)
42 |         for j in range(n):
43 |             dx, dy = model.test(x, y)
44 |             dc.line_to(x, y)
45 |             p = 1.0 - (j / (n - 1.0)) ** 2
46 |             a = p * 0.3
47 |             dc.set_source_rgba(r, g, b, a)
48 |             dc.set_line_width(width * p / scale)
49 |             if j:
50 |                 dc.stroke()
51 |             dc.move_to(x, y)
52 |             x += dx * f * m
53 |             y += dy * f * m
54 |             if x < -0.1 or y < -0.1 or x > 1.1 or y > 1.1:
55 |                 break
56 | 
57 | def main():
58 |     size = 4096
59 |     scale = size
60 |     surface = cairo.ImageSurface(cairo.FORMAT_RGB24, size, size)
61 |     dc = cairo.Context(surface)
62 |     dc.set_line_cap(cairo.LINE_CAP_ROUND)
63 |     dc.set_line_join(cairo.LINE_JOIN_ROUND)
64 |     dc.scale(scale, scale)
65 |     dc.set_source_rgb(0, 0, 0)
66 |     dc.paint()
67 |     model = Model()
68 |     for x, y in points(5):
69 |         model.add(x, y)
70 |     model.add(0.5, 0.5, 0.1)
71 |     for i in range(512):
72 |         h = random.random() * 0.06 + 0.04
73 |         s = random.random() * 0.8 + 0.2
74 |         v = random.random() * 0.2 + 0.8
75 |         r, g, b = colorsys.hsv_to_rgb(h, s, v)
76 |         w = random.random() * 48 + 16
77 |         draw_path(dc, model, scale, w, r, g, b)
78 |     surface.write_to_png('output.png')
79 | 
80 | if __name__ == '__main__':
81 |     main()
82 | 


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