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Poisson Disc
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from math import pi, sin, cos, hypot, floor | |
import cairocffi as cairo | |
import random | |
R = 0.012 | |
class Grid(object): | |
def __init__(self, r): | |
self.r = r | |
self.size = r / 2 ** 0.5 | |
self.cells = {} | |
def points(self): | |
return self.cells.values() | |
def normalize(self, x, y): | |
i = int(floor(x / self.size)) | |
j = int(floor(y / self.size)) | |
return (i, j) | |
def nearby(self, x, y): | |
result = [] | |
i, j = self.normalize(x, y) | |
for p in xrange(i - 2, i + 3): | |
for q in xrange(j - 2, j + 3): | |
if (p, q) in self.cells: | |
result.append(self.cells[(p, q)]) | |
return result | |
def nearest(self, x, y): | |
def func((bx, by)): | |
return hypot(x - bx, y - by) | |
return sorted(self.nearby(x, y), key=func) | |
def insert(self, x, y): | |
for bx, by in self.nearby(x, y): | |
if hypot(x - bx, y - by) < self.r: | |
return False | |
i, j = self.normalize(x, y) | |
self.cells[(i, j)] = (x, y) | |
return True | |
def poisson_disc(x1, y1, x2, y2, r, n): | |
x = x1 + (x2 - x1) / 2.0 | |
y = y1 + (y2 - y1) / 2.0 | |
active = [(x, y)] | |
grid = Grid(r) | |
grid.insert(x, y) | |
while active: | |
ax, ay = random.choice(active) | |
for i in xrange(n): | |
a = random.random() * 2 * pi | |
d = random.random() * r + r | |
x = ax + cos(a) * d | |
y = ay + sin(a) * d | |
if x < x1 or y < y1 or x > x2 or y > y2: | |
continue | |
if not grid.insert(x, y): | |
continue | |
active.append((x, y)) | |
break | |
else: | |
active.remove((ax, ay)) | |
return grid | |
def render(grid): | |
scale = 1024 | |
width = height = scale | |
surface = cairo.ImageSurface(cairo.FORMAT_RGB24, width, height) | |
dc = cairo.Context(surface) | |
dc.set_line_cap(cairo.LINE_CAP_ROUND) | |
dc.set_line_join(cairo.LINE_JOIN_ROUND) | |
dc.scale(scale, scale) | |
dc.set_source_rgb(0, 0, 0) | |
dc.paint() | |
for x1, y1 in grid.points(): | |
if hypot(x1 - 0.5, y1 - 0.5) > 0.45: | |
continue | |
for x2, y2 in grid.nearest(x1, y1)[1:2]: | |
if hypot(x2 - 0.5, y2 - 0.5) > 0.45: | |
continue | |
dc.move_to(x1, y1) | |
dc.line_to(x2, y2) | |
dc.set_source_rgb(0.996, 0.961, 0.922) | |
dc.set_line_width(R * 0.8) | |
dc.stroke_preserve() | |
dc.set_source_rgb(0.192, 0.243, 0.290) | |
dc.set_line_width(R * 0.4) | |
dc.stroke_preserve() | |
return surface | |
def main(): | |
grid = poisson_disc(0, 0, 1, 1, R, 32) | |
surface = render(grid) | |
surface.write_to_png('output.png') | |
if __name__ == '__main__': | |
main() |
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