# -*- coding: utf8 -*-
"""
繪制分形樹
"""
import turtledeflection_angle = 20         # 樹枝與樹干夾角
trunk_min_length = 5          # 樹干最小長度
trunk_step_length = 10        # 樹干每次遞減長度
trunk_length = 80             # 初始樹干長度
treetop_length = 30           # 樹梢部分長度
treetop_color = 'green'       # 主樹干顏色
treetrunk_color = 'brown'     # 樹梢部分顏色
pen_size = 10                 # 畫筆初始寬度
pen_step_size = 2             # 畫筆每次遞減寬度  
pen_min_size = 1              # 畫筆最小寬度def DrawFractalTree(trunk_length, pen_size):if trunk_length >= trunk_min_length:turtle.pensize(pen_size if pen_size > pen_min_size else pen_min_size)# 畫筆顏色turtle.pencolor((treetop_color, treetrunk_color)[trunk_length > treetop_length])# 畫樹干turtle.fd(trunk_length)# 繪制右側樹枝turtle.rt(deflection_angle)DrawFractalTree(trunk_length - trunk_step_length, pen_size - pen_step_size)# 繪制中間樹枝turtle.lt(deflection_angle)DrawFractalTree(trunk_length - trunk_step_length, pen_size - pen_step_size)# 繪制左側樹枝turtle.lt(deflection_angle)DrawFractalTree(trunk_length - trunk_step_length, pen_size - pen_step_size)# 返回樹干起始點turtle.rt(deflection_angle)turtle.penup()turtle.bk(trunk_length)turtle.pendown()def main():# 繪制速度 范圍[0,10]turtle.speed(10)# 初始畫筆位置    turtle.penup()turtle.left(90)turtle.backward(250)turtle.pendown()# 執行繪制DrawFractalTree(trunk_length, pen_size)turtle.exitonclick()if __name__ == '__main__':main()

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