import sys
from random import *
from OpenGL.GL import *
from OpenGL.GLU import *
from OpenGL.GLUT import *
from math import *

iterations = 1

def generatePlant(iterations=3):
    rules = { 'X':'F-[[X]+X]+F[+FX]-X', 'F' : 'FF' }
    s = 'X'
    for i in range(iterations):
        s2 = ''
        for c in s:
            if rules.has_key(c):
                s2 += rules[c]
            else:
                s2 += c
        s = s2
    return s.replace('X','')

def drawPlant(s):
    stack = []
    p = [0,0]
    angle = 0
    for c in s:
        if c == 'F':
            if len(stack) < 5:
                glLineWidth(5.0-len(stack))
            else:
                glLineWidth(1.0)
            glBegin(GL_LINES)
            glVertex2fv(p)
            p[0] += sin(angle)
            p[1] += cos(angle)
            glVertex2fv(p)
            glEnd()
        elif c == '-':
            angle -= radians(25) 
        elif c == '+':
            angle += radians(25)
        elif c == '[':
            stack.append( (p[:],angle) )
        elif c == ']':
            p,angle = stack.pop()
    
def draw():
    glClear(GL_COLOR_BUFFER_BIT)
    glMatrixMode(GL_PROJECTION)
    glLoadIdentity()
    gluOrtho2D(-100,100,0,150)
    glMatrixMode(GL_MODELVIEW)
    glLoadIdentity()
    
    plant = generatePlant(iterations)
    print plant
    drawPlant(plant)

    glutSwapBuffers()


def keyboard(key, x, y):
    global iterations
    if key == chr(27):
        sys.exit(0)
    elif key == '+':
       iterations += 1
    elif key == '-':
        iterations -= 1
    glutPostRedisplay()

glutInit([])
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE)
glutInitWindowSize(800,600)
glutCreateWindow(sys.argv[0])
glutDisplayFunc(draw)
glutKeyboardFunc(keyboard)
glutMainLoop()