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import sys, os
import turtle as tt
screen = tt.Screen()
class Lsystem:
"Class to compile and draw lsystem with turtle"
def __init__(self, save_every_frame=False,
speed=0):
self.name = ''
self.variables = []
self.constants = []
self.axiom = ''
self.rules = []
self.angle = 90
self.length = 10
self.generation = []
self.save_every_frame = save_every_frame
tt.speed(speed)
def __repr__(self):
return ("<Lsystem>\n\tname: %s\n\tvariables: %s\n\t" + \
"constants: %s\n\taxiom: %s\n\trules: %s\n\tangle:" +\
" %s\n</Lsystem>\n") \
% ((str(self.name), str(self.variables),
str(self.constants), str(self.axiom),
str(self.rules), str(self.angle)))
def parse_file(self,filename):
"method to parse a file containing Lsystem code"
print "Parsing file %s ..." % filename
with open(filename,'r') as infile:
lines = infile.readlines()
self.name = os.path.basename(filename).split('.')[0]
for line in lines:
split_line = line.split()
if (split_line[0] == 'variables:'):
self.variables = split_line[1:]
elif (split_line[0] == 'constants:'):
if split_line[1] != 'none':
self.constants = split_line[1:]
elif (split_line[0] in ['axiom:','start:']):
self.axiom = split_line[1]
elif (split_line[0] == 'rules:'):
for elem in split_line[1:]:
elem = elem[1:-1]
a,b = elem.split('->')
self.rules.append((a.strip(),b.strip()))
elif (split_line[0] == 'angle:'):
self.angle = int(split_line[1])
elif (split_line[0] == 'length:'):
self.length = int(split_line[1])
elif (split_line[0].startswith('#') or \
split_line[0] == ""):
pass # ignore comments and empty lines
else:
raise Exception(
'\n[ERROR] Cannot parse line: %s\n' % line)
if (self.name == '' or self.variables == [] or \
self.axiom == '' or self.rules == [] or \
self.angle == None):
print "[ERROR] Parsing failed. Missing some field"
print self
exit(1)
print "Finished parsing"
def compile(self, filename, number_of_generations):
"compiles the lsystem grammar code"
try:
self.parse_file(filename)
except IOError, e:
print "[ERROR] File \"%s\" not found" % \
filename
print "\nTry any of the following from examples directory"
print os.listdir('examples')
print "\nExample:"
print "python lsystem.py examples/pythagoriantree.txt 4"
exit(1)
print "Compiling ...",
self.generation.append(self.axiom)
for i in range(number_of_generations):
self.generation.append(self.expand(self.generation[i]))
print "Done"
# print the generated code
self.print_generations()
def expand(self,string):
"code generation with expansion technique"
expanded_string = ''
for character in string:
if character in self.constants:
expanded_string += character
elif character in self.variables:
for rule in self.rules:
if rule[0] == character:
expanded_string += rule[1]
break
else:
raise Exception(
'[ERROR] Unknown character %s in string %s\n' % \
((character, string)))
return expanded_string
def print_generations(self):
print "Generated code:"
for i, generation in enumerate(self.generation):
print "[ %d ] %s\n" % ((i,generation))
def draw(self):
"draws the lsystem on the screen"
stack = []
tt.penup()
tt.setpos(0, -200)
tt.seth(90)
tt.pendown()
print "Drawing the lsystem ..."
for i, codebit in enumerate(self.generation[-1]):
if codebit in ['F', 'A', 'B']:
tt.forward(self.length)
print '[ FRWD ] ', codebit
elif codebit == '+':
tt.right(self.angle)
print '[ RGHT ] ', codebit
elif codebit == '-':
tt.left(self.angle)
print '[ LEFT ] ', codebit
elif codebit == '[':
stack.append((tt.pos(), tt.heading()))
print '[ PUSH ] ', (tt.pos(), tt.heading())
elif codebit == ']':
position,heading = stack.pop()
print '[ POP ] ', (position, heading)
tt.penup()
tt.goto(position)
tt.seth(heading)
tt.pendown()
else:
print '[ NOP ] ', codebit
if self.save_every_frame:
self.save(frame=i)
print "Done drawing"
print "Saving file as %s.jpg" % self.name,
self.save()
print "Done"
def save(self, frame=None):
from PIL import Image
import io
screen = tt.getscreen()
canvas = screen.getcanvas()
postscript = canvas.postscript().encode('utf-8')
img = Image.open(io.BytesIO(postscript))
if frame:
name = self.name + "0" * (5 - len(str(frame))) + str(frame)
img.save('pics/%s.gif' % name)
else:
img.save('pics/%s.jpg' % self.name)
if __name__ == '__main__':
# instantiate Lsystem object
lsystem = Lsystem(save_every_frame=False, speed=0)
# save every frame to make gif for example
# speed is in range of 0 to 10
# speed (0=fastest, 1=slowest, 3=slow, 6=normal, 10=fast)
try:
lsystem.compile(sys.argv[1], #compile lsystem
int(sys.argv[2])) # specify the file name
# and generation number
print lsystem
lsystem.draw() # draw lsystem with turtle
except IndexError, e:
print "[ERROR] Wrong usage. Use the following syntax"
print "$ python lsystem.py filename number_of_generations\n"
print "Example: "
print "$ python lsystem.py examples/pythagoriantree.txt 4"
exit(1)
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