from turtle import *
 
#控制彩虹路徑
def path(pen, r, g, b):
 pen.penup()
 pen.goto(-400, -300)
 pen.pendown()
 pen.pencolor(r, g, b)
 pen.circle(1000, -180)
 pen.pensize(2)
 pen.right(0.05)
 
#繪制彩虹控制顏色
def Rainbow():
 pen = Turtle()
 pen.right(110)
 r = 255
 g = 0
 b = 0
 interval = 5
 colormode(255)
 # 由紅到黃
 while g < 256:
 path(pen, r, g, b)
 g = g + interval
 #由黃到綠
 g = 255
 while r > 0:
 r = r - interval
 path(pen, r, g, b)
 #由綠到青
 r = 0
 while (b < 255 ):
 b = b + interval
 path(pen, r, g, b)
 b = 255
 #由青到藍
 while (g > 0):
 g = g - interval
 path(pen, r, g, b)
 #由藍到紫到紅
 g = 0
 while r < 255:
 r = r + interval
 path(pen, r, g, b)
 
#文字輸出
def TextFun():
 text = Turtle()
 text.hideturtle()
 text.color("red")
 text.penup()
 text.setpos(100, -100)
 text.pendown()
 text.write("Rainbow", False, align="center", font=("Script MT Bold", 80, "bold"))
 
def main():
 setup(800, 600, 0, 0)
 title("rainbow")
 tracer(False)
 Rainbow()
 TextFun()
 tracer(True)
 mainloop()
 
if __name__ == '__main__':
 main()