源代码（还不是太了解~~~囧）
- # drawtree.py
- from turtle import Turtle, mainloop
- def tree(plist, l, a, f):
- """ plist is list of pens
- l is length of branch
- a is half of the angle between 2 branches
- f is factor by which branch is shortened
- from level to level."""
- if l > 5: #
- lst = []
- for p in plist:
- p.forward(l)#沿着当前的方向画画Move the turtle forward by the specified distance, in the direction the turtle is headed.
- q = p.clone()#Create and return a clone of the turtle with same position, heading and turtle properties.
- p.left(a) #Turn turtle left by angle units
- q.right(a)# turn turtle right by angle units, nits are by default degrees, but can be set via the degrees() and radians() functions.
- lst.append(p)#将元素增加到列表的最后
- lst.append(q)
- tree(lst, l*f, a, f)
- def main():
- p = Turtle()
- p.color("green")
- p.pensize(5)
- #p.setundobuffer(None)
- p.hideturtle() #Make the turtle invisible. It’s a good idea to do this while you’re in the middle of doing some complex drawing,
- #because hiding the turtle speeds up the drawing observably.
- #p.speed(10)
- # p.getscreen().tracer(1,0)#Return the TurtleScreen object the turtle is drawing on.
- p.speed(10)
- #TurtleScreen methods can then be called for that object.
- p.left(90)# Turn turtle left by angle units. direction 调整画笔
- p.penup() #Pull the pen up – no drawing when moving.
- p.goto(0,-200)#Move turtle to an absolute position. If the pen is down, draw line. Do not change the turtle’s orientation.
- p.pendown()# Pull the pen down – drawing when moving. 这三条语句是一个组合相当于先把笔收起来再移动到指定位置，再把笔放下开始画
- #否则turtle一移动就会自动的把线画出来
- #t = tree([p], 200, 65, 0.6375)
- t = tree([p], 200, 65, 0.6375)
- main()
