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#!/usr/bin/env python3
#coding:utf-8
# Author: mozman
# Purpose: svg examples
# Created: 08.09.2010
# Copyright (C) 2010, Manfred Moitzi
# License: MIT License
try:
import svgwrite
except ImportError:
# if svgwrite is not 'installed' append parent dir of __file__ to sys.path
import sys
from pathlib import Path
sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
import math
import svgwrite
LevyDragon = {'length':1, 'numAngle':4, 'level':16, 'init': 'FX',
'target': 'X', 'replacement': 'X+YF+', 'target2': 'Y',
'replacement2': '-FX-Y'}
KochSnowflake = {'length':1, 'numAngle':6, 'level':6, 'init': 'F++F++F',
'target': 'F', 'replacement': 'F-F++F-F', 'target2': '',
'replacement2': ''}
LevyCurve = {'length':1, 'numAngle':8, 'level':17, 'init': 'F',
'target': 'F', 'replacement': '+F--F+', 'target2': '',
'replacement2': ''}
HilbertSpaceFillingCurve = {'length':1, 'numAngle':4, 'level':5, 'init': 'L',
'target': 'L', 'replacement': '+RF-LFL-FR+', 'target2': 'R',
'replacement2': '-LF+RFR+FL-'}
def LSystem(name, formula=LevyCurve):
## {{{ http://code.activestate.com/recipes/577159/ (r1)
# L-System Fractals
# FB - 201003276
# image size
# generate the fractal drawing string
def _LSystem(formula):
state = formula['init']
target = formula['target']
replacement = formula['replacement']
target2 = formula['target2']
replacement2 = formula['replacement2']
level = formula['level']
for counter in range(level):
state2 = ''
for character in state:
if character == target:
state2 += replacement
elif character == target2:
state2 += replacement2
else:
state2 += character
state = state2
return state
print("creating: %s\n" % name)
xmin, ymin = (100000, 100000)
xmax, ymax = (-100000, -100000)
numAngle = formula['numAngle']
length = formula['length']
fractal = _LSystem(formula)
na = 2 * math.pi / numAngle
sn = []
cs = []
for i in range(numAngle):
sn.append(math.sin(na * i))
cs.append(math.cos(na * i))
x = 0.0
y = 0.0
# jx = int((x - xa) / (xb - xa) * (imgx - 1))
# jy = int((y - ya) / (yb - ya) * (imgy - 1))
k = 0
dwg = svgwrite.Drawing(name, debug=True)
curve = dwg.polyline(points=[(x, y)], stroke='green', fill='none', stroke_width=0.1)
for ch in fractal:
if ch == 'F':
# turtle forward(length)
x += length * cs[k]
y += length * sn[k]
curve.points.append( (x, y) )
# find maxima
xmin = min(xmin, x)
xmax = max(xmax, x)
ymin = min(ymin, y)
ymax = max(ymax, y)
elif ch == '+':
# turtle right(angle)
k = (k + 1) % numAngle
elif ch == '-':
# turtle left(angle)
k = ((k - 1) + numAngle) % numAngle
print("L-System with %d segements.\n" % (len(curve.points)-1))
dwg.viewbox(xmin, ymin, xmax-xmin, ymax-ymin)
dwg.add(curve)
dwg.save()
## end of http://code.activestate.com/recipes/577159/ }}}
if __name__ == '__main__':
LSystem('lsys_hilbertspacefillingcurve.svg', formula=HilbertSpaceFillingCurve)
LSystem('lsys_levydragon.svg', formula=LevyDragon)
LSystem('lsys_levycurve.svg', formula=LevyCurve)
LSystem('lsys_kochsnowflake.svg', formula=KochSnowflake)
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