"""
    Single Rule L-System Generator with DXF Output
    Jordan Perr - 2010 - All Rights Reserved
    Version 1
"""

###############        DEPENDENCIES       ################

from math import cos, sin, pi
import sdxf


###############       CONFIGURATION       ################

# Path to output file
OFILE = "fern.dxf"

# Start position [xcor, ycor, theta]
START = [0,0,pi/2]

# Segment of depth 0 will be this long
SCALE = 20

# How many times should RULES be applied?
# (Warning: Large DEPTH may freeze your machine.)
DEPTH = 4

# L-System configuration (See ISBN:0262561271)
ANGLE = 0.13962634
DS    = 0.4
AXIOM = "F"
RULE  = "F=|[5+F][7-F]-|[4+F][6-F]-|[3+F][5-F]-|F"


##################        CODE      #####################

# Apply rule DEPTH times. Create turtle's roadmap.
rule = RULE.split('=')
commands = AXIOM[:]
for step in range(DEPTH):
	commands = commands.replace(rule[0], '('+rule[1]+')')

# Set Up sdxf AutoCad dxf library.
CAD = sdxf.Drawing()
CAD.styles.append(sdxf.Style())
CAD.views.append(sdxf.View('Normal'))
CAD.views.append(sdxf.ViewByWindow('Window',leftBottom=(0,0),rightTop=(1,1)))  #idem

# Precompute line segment distances. Prepare to draw.
dst = [SCALE*(DS**l) for l in range(1,DEPTH+2)]
stack = [START]
coef = 1
dep = 0

# Draw the L-System using a virtual turtle.
for c in commands:
	if c in ['1','2','3','4','5','6','7','8','9']:
		coef = int(c)
	elif c == '(':
		dep = dep + 1
	elif c == ')':
		dep = dep - 1
	elif c == '[':
		stack.append(list(stack[-1]))
	elif c == ']':
		stack.pop()
	elif c == 'F' or c == '|':
		top = stack[-1]
		point1 = list(top)
		top[0] = top[0] + dst[dep]*cos(top[2])
		top[1] = top[1] + dst[dep]*sin(top[2])
		CAD.append(sdxf.Line(points=[point1[:2], list(top[:2])]))
	elif c == '+':
		top = stack[-1]
		top[2] = top[2] + ANGLE*coef
		coef = 1
	elif c == '-':
		top = stack[-1]
		top[2] = top[2] - ANGLE*coef
		coef = 1

# Save the DXF file
CAD.saveas(OFILE)