275 lines
9.0 KiB
Python
275 lines
9.0 KiB
Python
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# Source: https://github.com/python/pyperformance
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# License: MIT
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# create chaosgame-like fractals
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# Copyright (C) 2005 Carl Friedrich Bolz
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import math
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import random
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class GVector(object):
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def __init__(self, x=0, y=0, z=0):
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self.x = x
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self.y = y
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self.z = z
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def Mag(self):
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return math.sqrt(self.x ** 2 + self.y ** 2 + self.z ** 2)
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def dist(self, other):
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return math.sqrt((self.x - other.x) ** 2
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+ (self.y - other.y) ** 2
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+ (self.z - other.z) ** 2)
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def __add__(self, other):
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if not isinstance(other, GVector):
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raise ValueError("Can't add GVector to " + str(type(other)))
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v = GVector(self.x + other.x, self.y + other.y, self.z + other.z)
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return v
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def __sub__(self, other):
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return self + other * -1
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def __mul__(self, other):
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v = GVector(self.x * other, self.y * other, self.z * other)
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return v
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__rmul__ = __mul__
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def linear_combination(self, other, l1, l2=None):
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if l2 is None:
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l2 = 1 - l1
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v = GVector(self.x * l1 + other.x * l2,
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self.y * l1 + other.y * l2,
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self.z * l1 + other.z * l2)
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return v
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def __str__(self):
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return "<%f, %f, %f>" % (self.x, self.y, self.z)
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def __repr__(self):
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return "GVector(%f, %f, %f)" % (self.x, self.y, self.z)
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class Spline(object):
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"""Class for representing B-Splines and NURBS of arbitrary degree"""
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def __init__(self, points, degree, knots):
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"""Creates a Spline.
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points is a list of GVector, degree is the degree of the Spline.
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"""
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if len(points) > len(knots) - degree + 1:
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raise ValueError("too many control points")
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elif len(points) < len(knots) - degree + 1:
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raise ValueError("not enough control points")
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last = knots[0]
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for cur in knots[1:]:
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if cur < last:
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raise ValueError("knots not strictly increasing")
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last = cur
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self.knots = knots
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self.points = points
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self.degree = degree
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def GetDomain(self):
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"""Returns the domain of the B-Spline"""
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return (self.knots[self.degree - 1],
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self.knots[len(self.knots) - self.degree])
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def __call__(self, u):
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"""Calculates a point of the B-Spline using de Boors Algorithm"""
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dom = self.GetDomain()
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if u < dom[0] or u > dom[1]:
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raise ValueError("Function value not in domain")
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if u == dom[0]:
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return self.points[0]
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if u == dom[1]:
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return self.points[-1]
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I = self.GetIndex(u)
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d = [self.points[I - self.degree + 1 + ii]
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for ii in range(self.degree + 1)]
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U = self.knots
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for ik in range(1, self.degree + 1):
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for ii in range(I - self.degree + ik + 1, I + 2):
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ua = U[ii + self.degree - ik]
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ub = U[ii - 1]
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co1 = (ua - u) / (ua - ub)
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co2 = (u - ub) / (ua - ub)
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index = ii - I + self.degree - ik - 1
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d[index] = d[index].linear_combination(d[index + 1], co1, co2)
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return d[0]
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def GetIndex(self, u):
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dom = self.GetDomain()
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for ii in range(self.degree - 1, len(self.knots) - self.degree):
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if u >= self.knots[ii] and u < self.knots[ii + 1]:
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I = ii
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break
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else:
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I = dom[1] - 1
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return I
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def __len__(self):
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return len(self.points)
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def __repr__(self):
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return "Spline(%r, %r, %r)" % (self.points, self.degree, self.knots)
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def write_ppm(im, w, h, filename):
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with open(filename, "wb") as f:
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f.write(b'P6\n%i %i\n255\n' % (w, h))
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for j in range(h):
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for i in range(w):
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val = im[j * w + i]
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c = val * 255
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f.write(b'%c%c%c' % (c, c, c))
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class Chaosgame(object):
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def __init__(self, splines, thickness, subdivs):
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self.splines = splines
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self.thickness = thickness
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self.minx = min([p.x for spl in splines for p in spl.points])
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self.miny = min([p.y for spl in splines for p in spl.points])
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self.maxx = max([p.x for spl in splines for p in spl.points])
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self.maxy = max([p.y for spl in splines for p in spl.points])
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self.height = self.maxy - self.miny
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self.width = self.maxx - self.minx
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self.num_trafos = []
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maxlength = thickness * self.width / self.height
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for spl in splines:
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length = 0
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curr = spl(0)
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for i in range(1, subdivs + 1):
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last = curr
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t = 1 / subdivs * i
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curr = spl(t)
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length += curr.dist(last)
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self.num_trafos.append(max(1, int(length / maxlength * 1.5)))
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self.num_total = sum(self.num_trafos)
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def get_random_trafo(self):
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r = random.randrange(int(self.num_total) + 1)
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l = 0
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for i in range(len(self.num_trafos)):
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if r >= l and r < l + self.num_trafos[i]:
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return i, random.randrange(self.num_trafos[i])
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l += self.num_trafos[i]
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return len(self.num_trafos) - 1, random.randrange(self.num_trafos[-1])
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def transform_point(self, point, trafo=None):
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x = (point.x - self.minx) / self.width
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y = (point.y - self.miny) / self.height
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if trafo is None:
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trafo = self.get_random_trafo()
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start, end = self.splines[trafo[0]].GetDomain()
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length = end - start
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seg_length = length / self.num_trafos[trafo[0]]
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t = start + seg_length * trafo[1] + seg_length * x
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basepoint = self.splines[trafo[0]](t)
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if t + 1 / 50000 > end:
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neighbour = self.splines[trafo[0]](t - 1 / 50000)
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derivative = neighbour - basepoint
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else:
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neighbour = self.splines[trafo[0]](t + 1 / 50000)
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derivative = basepoint - neighbour
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if derivative.Mag() != 0:
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basepoint.x += derivative.y / derivative.Mag() * (y - 0.5) * \
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self.thickness
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basepoint.y += -derivative.x / derivative.Mag() * (y - 0.5) * \
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self.thickness
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else:
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# can happen, especially with single precision float
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pass
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self.truncate(basepoint)
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return basepoint
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def truncate(self, point):
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if point.x >= self.maxx:
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point.x = self.maxx
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if point.y >= self.maxy:
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point.y = self.maxy
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if point.x < self.minx:
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point.x = self.minx
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if point.y < self.miny:
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point.y = self.miny
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def create_image_chaos(self, w, h, iterations, rng_seed):
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# Always use the same sequence of random numbers
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# to get reproductible benchmark
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random.seed(rng_seed)
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im = bytearray(w * h)
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point = GVector((self.maxx + self.minx) / 2,
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(self.maxy + self.miny) / 2, 0)
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for _ in range(iterations):
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point = self.transform_point(point)
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x = (point.x - self.minx) / self.width * w
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y = (point.y - self.miny) / self.height * h
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x = int(x)
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y = int(y)
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if x == w:
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x -= 1
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if y == h:
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y -= 1
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im[(h - y - 1) * w + x] = 1
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return im
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###########################################################################
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# Benchmark interface
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bm_params = {
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(100, 50): (0.25, 100, 50, 50, 50, 1234),
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(1000, 1000): (0.25, 200, 400, 400, 1000, 1234),
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(5000, 1000): (0.25, 400, 500, 500, 7000, 1234),
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}
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def bm_setup(params):
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splines = [
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Spline([
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GVector(1.597, 3.304, 0.0),
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GVector(1.576, 4.123, 0.0),
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GVector(1.313, 5.288, 0.0),
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GVector(1.619, 5.330, 0.0),
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GVector(2.890, 5.503, 0.0),
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GVector(2.373, 4.382, 0.0),
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GVector(1.662, 4.360, 0.0)],
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3, [0, 0, 0, 1, 1, 1, 2, 2, 2]),
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Spline([
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GVector(2.805, 4.017, 0.0),
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GVector(2.551, 3.525, 0.0),
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GVector(1.979, 2.620, 0.0),
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GVector(1.979, 2.620, 0.0)],
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3, [0, 0, 0, 1, 1, 1]),
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Spline([
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GVector(2.002, 4.011, 0.0),
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GVector(2.335, 3.313, 0.0),
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GVector(2.367, 3.233, 0.0),
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GVector(2.367, 3.233, 0.0)],
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3, [0, 0, 0, 1, 1, 1])
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]
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chaos = Chaosgame(splines, params[0], params[1])
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image = None
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def run():
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nonlocal image
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_, _, width, height, iter, rng_seed = params
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image = chaos.create_image_chaos(width, height, iter, rng_seed)
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def result():
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norm = params[4]
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# Images are not the same when floating point behaviour is different,
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# so return percentage of pixels that are set (rounded to int).
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#write_ppm(image, params[2], params[3], 'out-.ppm')
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pix = int(100 * sum(image) / len(image))
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return norm, pix
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return run, result
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