When I try to run my code, my python turtle window just hangs; I can't move also. I've tried removing the win_pen and it worked, but I don't know what inside the win_pen is making it hang.
It also gives me the spinning wheel since I am on Mac, and I am not sure if that is the problem for this. I'm on Big Sur 11.1 by the way.
edit: The indents are right on my screen, just a copy and paste problem
Code:
import turtle
import os
import math
import random
from random import randint
score = 0
# Set Up Screen
wn = turtle.Screen()
wn.bgcolor("black")
wn.title("test")
# Draw border
border_pen = turtle.Turtle()
border_pen.speed(0)
border_pen.color("white")
border_pen.penup()
border_pen.setposition(-300,-300)
border_pen.pendown()
border_pen.hideturtle()
border_pen.pensize(3)
for side in range(4):
border_pen.fd(600)
border_pen.lt(90)
# Draw Winning Area
win_pen = turtle.Turtle()
win_pen.hideturtle()
win_pen.shape("square")
win_pen.penup()
win_pen.setposition(0,267.7)
win_pen.shapesize(3,29.8)
# Show Score on Screen
score_pen = turtle.Turtle()
score_pen.speed(0)
score_pen.color("white")
score_pen.penup()
score_pen.setposition(-290, 303)
scorestring = "Score: %s" %score
score_pen.write(scorestring, False, align="left", font=("Ubuntu", 14, "normal"))
score_pen.hideturtle()
# Set up Player 1
player1 = turtle.Turtle()
player1.color("blue")
player1.shape("triangle")
player1.penup()
player1.speed(0)
player1.setposition(0, -250)
player1.setheading(90)
player1speed = 15
# Set Up Enemies
en = 8
enemies = []
for i in range(en):
enemies.append(turtle.Turtle())
for enemy in enemies:
enemy.color("red")
enemy.shape("square")
enemy.penup()
enemy.speed(0)
enemy.goto(randint(-280,280),randint(-280,280))
enemy.shapesize(2,2)
enemyspeed = 2
# Draw Winning Area
win_pen = turtle.Turtle()
win_pen.hideturtle()
win_pen.shape("square")
win_pen.penup()
win_pen.setposition(0,267.7)
win_pen.shapesize(3,29.8)
#Define bullet state
#ready - ready to fire
#fire - bullet is firing
bulletstate = "ready"
def left():
x = player1.xcor()
player1.setheading(180)
player1.forward(player1speed)
if x < -280:
x = - 280
player1.setx(x)
def right():
x = player1.xcor()
player1.setheading(0)
player1.forward(player1speed)
if x > 280:
x = 280
player1.setx(x)
def up():
y = player1.ycor()
player1.setheading(90)
player1.forward(player1speed)
if y > 280:
y = 280
player1.sety(y)
def down():
y = player1.ycor()
player1.setheading(270)
player1.forward(player1speed)
if y < -280:
y = 280
player1.sety(y)
def isCollision(t1, t2):
distance = math.sqrt(math.pow(t1.xcor()-t2.xcor(),2)+math.pow(t1.ycor()-t2.ycor(),2))
if distance < 15:
return True
else:
return False
turtle.listen()
turtle.onkey(left, "a")
turtle.onkey(right, "d")
turtle.onkey(up, "w")
turtle.onkey(down, "s")
# Main Game Loop
while True:
if isCollision(player1, win_pen):
player1.setposition(0, -250)
player1.setheading(90)
There are several problems with your code: don't use while True: in an event-driven world like turtle -- let the event handler do its job; your collision logic is incorrect as it measures from the center of the turtles whereas we're really only concerned with the y position of the two turtles; you seem to be resetting the player in the wrong direction; you implement the winning area twice.
I've rewritten, and simplified, your code below incorporating the above changes and some other tweaks:
from turtle import Screen, Turtle
from random import randint
ENEMY_COUNT = 8
PLAYER_SPEED = 15
def left():
player.setheading(180)
player.setx(max(-280, player.xcor() - PLAYER_SPEED))
check_collision(player, win_pen)
def right():
player.setheading(0)
player.setx(min(280, player.xcor() + PLAYER_SPEED))
check_collision(player, win_pen)
def up():
player.setheading(90)
player.sety(min(280, player.ycor() + PLAYER_SPEED))
check_collision(player, win_pen)
def down():
player.setheading(270)
player.sety(max(-280, player.ycor() - PLAYER_SPEED))
check_collision(player, win_pen)
def check_collision(player, win_pen):
if abs(player.ycor() - win_pen.ycor()) < 15:
player.sety(-250)
player.setheading(90)
score = 0
# Set Up Screen
screen = Screen()
screen.bgcolor('black')
# Draw border
border_pen = Turtle()
border_pen.hideturtle()
border_pen.pensize(3)
border_pen.color('white')
border_pen.speed('fastest')
border_pen.penup()
border_pen.setposition(-300, -300)
border_pen.pendown()
for _ in range(4):
border_pen.forward(600)
border_pen.left(90)
# Draw Winning Area
win_pen = Turtle()
win_pen.shape('square')
win_pen.shapesize(3, 29.8)
win_pen.color('gray')
win_pen.penup()
win_pen.sety(267.7)
# Show Score on Screen
score_pen = Turtle()
score_pen.hideturtle()
score_pen.color('white')
score_pen.penup()
score_pen.setposition(-290, 303)
scorestring = "Score: %s" %score
score_pen.write(scorestring, False, align='left', font=('Ubuntu', 14, 'normal'))
# Set up Player
player = Turtle()
player.shape('triangle')
player.color('blue')
player.speed('fastest')
player.setheading(90)
player.penup()
player.setx(-250)
# Set Up Enemies
enemies = []
for _ in range(ENEMY_COUNT):
enemy = Turtle()
enemy.color('red')
enemy.shape('square')
enemy.shapesize(2)
enemy.speed('fastest')
enemy.penup()
enemy.goto(randint(-280, 280), randint(-280, 280))
enemies.append(enemy)
screen.onkey(left, 'a')
screen.onkey(right, 'd')
screen.onkey(up, 'w')
screen.onkey(down, 's')
screen.listen()
screen.mainloop()
Related
In python
import time
from turtle import Turtle, Screen
# screen height and width
height = 600
width = 600
# snake initial positinn
x_coordinate = 0
y_coordinate = 0
game_on = True
screen = Screen()
screen.bgcolor("black")
screen.setup(height=height, width=width)
screen.title("Snake Game")
full_snake = []
screen.tracer(0)
# create a snake 3X3
for _ in range(3):
snake = Turtle("square")
snake.color("white")
snake.penup()
snake.goto(x_coordinate, y_coordinate)
x_coordinate -= 20
full_snake.append(snake)
snake_head = full_snake[0]
# function to operate the snake
def up():
if snake_head.heading() != 270:
snake_head.setheading(90)
def down():
if snake_head.heading() != 90:
snake_head.setheading(270)
def right():
if snake_head.heading() != 180:
snake_head.setheading(0)
def left():
if snake_head.heading() != 0:
snake_head.setheading(180)
screen.listen()
screen.onkey(up, "w")
screen.onkey(down, "s")
screen.onkey(right, "d")
screen.onkey(left, "a")
# function for snakes part to attached
def attached():
for i in range(len(full_snake) - 1, 0, -1):
new_x = full_snake[i - 1].xcor()
new_y = full_snake[i - 1].ycor()
full_snake[i].goto(new_x, new_y)
snake_head.fd(20)
# to move the snake
while game_on:
snake_head.speed(1)
screen.update()
time.sleep(0.1)
for snake in full_snake:
attached()
screen.exitonclick()
in this code snake speed is fast, I want to slow down to normal where I can placed speed() method or any method
Turtle module from python
expected output : speed of snake to be normal without detaching other two blocks
.................................................................................................................................................................................................................................................................................................................................
You can try the ontimer() method instead to control the snake movement. I modified your code a bit. You can check if the snake hits the wall too and set game_on to false in the move_snake function.
import time
from turtle import Turtle, Screen
# screen height and width
height = 600
width = 600
# snake initial position
x_coordinate = 0
y_coordinate = 0
game_on = True
screen = Screen()
screen.bgcolor("black")
screen.setup(height=height, width=width)
screen.title("Snake Game")
full_snake = []
screen.tracer(0)
# create a snake 3X3
for _ in range(3):
snake = Turtle("square")
snake.color("white")
snake.penup()
snake.goto(x_coordinate, y_coordinate)
x_coordinate -= 20
full_snake.append(snake)
snake_head = full_snake[0]
# function to operate the snake
def up():
if snake_head.heading() != 270:
snake_head.setheading(90)
def down():
if snake_head.heading() != 90:
snake_head.setheading(270)
def right():
if snake_head.heading() != 180:
snake_head.setheading(0)
def left():
if snake_head.heading() != 0:
snake_head.setheading(180)
screen.listen()
screen.onkey(up, "w")
screen.onkey(down, "s")
screen.onkey(right, "d")
screen.onkey(left, "a")
# function for snake parts to attached
def attached():
for i in range(len(full_snake) - 1, 0, -1):
new_x = full_snake[i - 1].xcor()
new_y = full_snake[i - 1].ycor()
full_snake[i].goto(new_x, new_y)
snake_head.fd(20)
# New function to move the snake
def move_snake():
attached()
screen.update()
# updated the height and width variables to fit the actual screen size (useful when screen is resized)
height = screen.window_height()
width = screen.window_width()
# check if the snake head hits the wall (19 or 20 pixels away looks fine but can be ajusted) then set game_on to false and stop the function execution
if snake_head.xcor() >= width/2 - 20 or snake_head.xcor() <= -width/2 + 19 or snake_head.ycor() >= height/2 - 19 or snake_head.ycor() <= -height/2 + 20:
game_on = False
return
# timer to recursively call the move_snake function every 500 milliseconds
screen.ontimer(move_snake, 500) # adapt to your desired speed (the lower the faster)
# start moving the snake
move_snake()
screen.exitonclick()
I have written some code but can't get the ball to bounce on the floor or the ceiling naturally. Please help!
I've already tried getting the ball heading with ball_heading = ball.heading, but that didn't work
#Python 3.6.3
from turtle import *
import math
import random
#Screen Setup
bgcolor("black")
wn = Screen()
wn.title("Pong")
#Drawing Border
bd = Turtle()
bd.pencolor("white")
bd.pensize(3)
bd.hideturtle()
bd.penup()
bd.setposition(-400, -300)
bd.pendown()
bd.speed(0)
bd.pendown()
for line in range(2):
bd.forward(800)
bd.left(90)
bd.forward(600)
bd.left(90)
bd.penup()
bd.setposition(0, 300)
bd.setheading(270)
bd.pendown()
for dash in range(30):
bd.forward(10)
bd.penup()
bd.forward(10)
bd.pendown()
#Creating Paddles
#Paddle 1
player1 = Turtle()
player1.color("white")
player1.shape("square")
player1.shapesize(stretch_wid=5, stretch_len=1)
player1.penup()
player1.setposition(-370, 0)
#Paddle 2
player2 = Turtle()
player2.color("white")
player2.shape("square")
player2.shapesize(stretch_wid=5, stretch_len=1)
player2.penup()
player2.setposition(370, 0)
#Creating the ball
ball = Turtle()
ball.color("white")
ball.shape("square")
ball.speed(0)
ball.penup()
ball.setposition(0, 0)
ball.setheading(random.randint(0, 360))
#Moving the player
playerspeed = 15
#p1
def move_up():
y = player1.ycor()
y += playerspeed
#Setting the boundries
if y > 245:
y = 245
player1.sety(y)
def move_down():
y = player1.ycor()
y -= playerspeed
#Setting the boundries
if y < -245:
y = -245
player1.sety(y)
#p2
def move_up2():
y = player2.ycor()
y += playerspeed
#Setting the boundries
if y > 245:
y = 245
player2.sety(y)
def move_down2():
y = player2.ycor()
y -= playerspeed
#Setting the boundries
if y < -245:
y = -245
player2.sety(y)
#Ball movement
def ball_fd():
ball.forward(3)
#Ball ceiling / floor bounce
def ball_bounce():
by = ball.ycor()
if by > 279:
by = 279
ball.sety(by)
bx = ball.ycor()
if bx < -279:
bx = -279
ball.setx(bx)
#binding
listen()
onkey(move_up, "Up")
onkey(move_down, "Down")
onkey(move_up2, "w")
onkey(move_down2, "s")
#Making the ball move / main game loop
while True:
ball_fd()
ball_bounce()
Sorry the code is kind of long, but feel free to copy + paste it into IDLE or whatever.
Thank you
You didn't turn the ball when it hit the floor or ceiling.
while True:
ball.fd(3)
by = ball.ycor()
if abs(by) > 279:
ball.setheading(-ball.heading())
I am trying to create a simple python turtle game where the turtle needs to make it to the circle, while avoiding the moving square. I would like the code to count down lives and move the turtle back to the beginning until there are 0 lives left. The code below allows for one play and then the motion loop does not repeat.
I have tried a recursive function (move(3)), but then the onkey commands don't work....
import turtle, random, time
#background
canvas = turtle.Screen()
canvas.bgcolor('black')
#Pen
pen = turtle.Turtle()
pen.penup()
pen.color('white')
pen.hideturtle()
pen.penup()
#Lilypad
pad = turtle.Turtle()
pad.hideturtle()
pad.color('yellow')
pad.shape('circle')
pad.penup()
pad.setposition(0,290)
pad.showturtle()
#Turtle
player = turtle.Turtle()
player.hideturtle()
player.shape('turtle')
player.color('green')
player.penup()
player.left(90)
player.setposition(0, -290)
player.showturtle()
#truck
truck1 = turtle.Turtle()
truck1.hideturtle()
truck1.shape('square')
truck1.color('blue')
truck1.penup()
truck1.showturtle()
speed = random.randint(1,5)
def move():
#move player and truck
player.forward(2)
truck1.forward(speed)
if truck1.xcor() > 300 or truck1.xcor() < -300:
truck1.right(180)
#win if hit the lilypad
if player.distance(pad)<10:
pen.penup()
pen.setposition(0,-50)
pen.write('You win!', align='left', font=('Arial', 36, 'normal'))
done()
#lose a life if hit the truck
if player.distance(truck1) < 30:
player.setposition(0,-290)
life = life - 1
while life > 0:
pen.penup()
pen.setposition(0,-60)
pen.write('Try again', align='left', font=('Arial', 36, 'normal'))
time.sleep(1)
pen.clear()
move()
#game over if 0 lives left
pen.penup()
pen.setposition(0,-60)
pen.write('Game over!', align='left', font=('Arial', 36, 'normal'))
done()
canvas.ontimer(move,10)
canvas.onkey(lambda:player.setheading(90),'Up')
canvas.onkey(lambda:player.setheading(180),'Left')
canvas.onkey(lambda:player.setheading(0),'Right')
canvas.onkey(lambda:player.setheading(270),'Down')
canvas.listen()
life = 3
move()
canvas.mainloop()
The key to this is to move all your initialization code into a function, which invokes your move() function as it's last step. The first thing that the initialization code does is call canvas.clear() which pretty much wipes out everything. Then your move() function makes a choice at the end whether to call itself on the next timer iteration, or call the initialize code on the next timer iteration to reset everything and start a new game.
Below is your code reworked along the above lines as well as various teaks:
from turtle import Screen, Turtle
from random import randint
from time import sleep
FONT = ('Arial', 36, 'normal')
def initialize():
global pen, pad, player, truck, speed, life
canvas.clear() # assume that this resets *everything*
# background
canvas.bgcolor('black')
# Pen
pen = Turtle(visible=False)
pen.color('white')
pen.penup()
# Lilypad
pad = Turtle('circle', visible=False)
pad.color('yellow')
pad.penup()
pad.setposition(0, 290)
pad.showturtle()
# Turtle
player = Turtle('turtle', visible=False)
player.color('green')
player.penup()
player.setheading(90)
player.setposition(0, -290)
player.showturtle()
# truck
truck = Turtle('square', visible=False)
truck.color('blue')
truck.penup()
truck.showturtle()
speed = randint(1, 5)
canvas.onkey(lambda: player.setheading(90), 'Up')
canvas.onkey(lambda: player.setheading(180), 'Left')
canvas.onkey(lambda: player.setheading(0), 'Right')
canvas.onkey(lambda: player.setheading(270), 'Down')
canvas.listen()
life = 3
move()
def move():
global life
# move player and truck
player.forward(2)
truck.forward(speed)
if not -300 < truck.xcor() < 300:
truck.right(180)
# lose a life if hit the truck
if player.distance(truck) < 20:
player.setposition(0, -290)
life -= 1
if life > 0:
pen.setposition(0, -60)
pen.write('Try again', font=FONT)
sleep(1)
pen.clear()
# win if hit the lilypad
if player.distance(pad) < 20:
pen.setposition(0, -50)
pen.write('You win!', font=FONT)
canvas.ontimer(initialize, 1000)
elif life == 0: # game over if 0 lives left
pen.setposition(0, -60)
pen.write('Game over!', font=FONT)
canvas.ontimer(initialize, 1000)
else:
canvas.ontimer(move, 10)
canvas = Screen()
pen = None
pad = None
player = None
truck = None
speed = -1
life = -1
initialize()
canvas.mainloop()
This should let you play over again whether you win or run out of lives.
I have gotten an issue where an enemy turtle stops when I shoot. I am relatively new to python so I know that my code is pretty bad. I cant seem to spot why this happens but I'm assuming its got something to do with the while loop.
here is the code:
(i have added notes so it is easy to skip to important parts of it)
import turtle
import os
#wn is window
#bp = border
bullet = 'ready'
#screen setup
wn = turtle.Screen()
wn.bgcolor('black')
wn.title('SPACE.INVADERS')
#border
bp = turtle.Turtle()
bp.speed(0)
bp.color('green')
bp.penup()
bp.setposition(-300,-300)
bp.pendown()
count=0
while count != 5:
count= (count+1)
bp.fd(600)
bp.lt(90)
bp.hideturtle()
#player
p = turtle.Turtle()
p.color('red')
p.shape('triangle')
p.penup()
p.speed(0)
p.setposition(0,-250)
p.setheading(90)
#enemy
e = turtle.Turtle()
e.penup()
e.speed(0)
e.shape('square')
e.shapesize(1.25,1.25)
e.color('orange')
e.setpos(-250,250)
e.speed(1)
#p = player
#ps = player speed
ps = 15
#moving left and right
def left_mov():
x = p.xcor()
x -= ps
p.setx(x)
def right_mov():
x = p.xcor()
x += ps
p.setx(x)
#shooting
def shoot():
global bullet
if bullet == 'ready':
bullet = 'fire'
shot= turtle.Turtle()
shot.penup()
shot.speed(0)
shot.goto(p.pos())
shot.color('white')
shot.shape('triangle')
shot.shapesize(0.5)
shot.lt(90)
shot.speed(1)
shot.fd(550)
bullet = 'ready'
#bindings
turtle.listen()
turtle.onkey(left_mov, 'Left')
turtle.onkey(right_mov, 'Right')
turtle.onkey(shoot, 'space')
#enemy movement
while True:
e.fd(500)
e.rt(90)
e.fd(25)
e.rt(90)
e.fd(500)
e.lt(90)
e.fd(25)
e.lt(90)
I'm assuming its got something to do with the while loop
Yes, it shouldn't be there! In an event-driven world like turtle, there should never be a while True: loop. Instead, we need a timer event that fires off on regular intervals that does incremental updates of the objects in motion (enemy and bullet) so they appear to move at the same time. Below is my rework of your code using a timer event:
from turtle import Screen, Turtle
# moving left and right
def left_move():
player.setx(player.xcor() - player_speed)
def right_move():
player.setx(player.xcor() + player_speed)
# screen setup
screen = Screen()
screen.bgcolor('black')
screen.title('SPACE.INVADERS')
# border
border = Turtle(visible=False)
border.speed('fastest')
border.color('green')
border.penup()
border.setposition(-300, -300)
border.pendown()
for _ in range(4):
border.forward(600)
border.left(90)
# player
player = Turtle('triangle')
player.speed('fastest')
player.color('red')
player.penup()
player.setposition(0, -250)
player.setheading(90)
player_speed = 15
# enemy
enemy = Turtle('square')
enemy.speed('fast')
enemy.shapesize(1.25)
enemy.color('orange')
enemy.penup()
enemy.setpos(-250, 250)
enemy_speed = 6 # enemy speed
enemy_direction = 1 # enemy direction
# bullet
bullet = Turtle('triangle', visible=False)
bullet.speed('fastest')
bullet.color('white')
bullet.shapesize(0.5)
bullet.penup()
bullet.left(90)
bullet_speed = 9 # bullet speed
# shooting
def shoot():
if not bullet.isvisible():
bullet.goto(player.position())
bullet.showturtle()
def move():
global enemy_direction
if bullet.isvisible():
if bullet.ycor() > 275:
bullet.hideturtle()
else:
bullet.forward(bullet_speed)
# enemy movement
enemy.forward(enemy_direction * enemy_speed)
enemy.settiltangle(enemy.tiltangle() + 3) # just for fun
x, y = enemy.position()
if x > 250 or x < -250:
enemy_direction *= -1
enemy.sety(y - 25)
screen.ontimer(move, 50)
# bindings
screen.onkey(left_move, 'Left')
screen.onkey(right_move, 'Right')
screen.onkey(shoot, 'space')
screen.listen()
move()
screen.mainloop()
This should give you the basic functionality you need to move forward and add collision detection (bullet to enemy, enemy to player, player to wall) and scoring.
Also note that turtles are global entities so creating a new bullet every time you need one is a bad idea. Even if you evenually allow overlapping bullets, keep a reusable set of bullets for that purpose.
I wanted to make a snake game in turtle but I can't seem to get the tail segments to follow the leader. As if to say I can't get the first body part to follow the head, and then the second body part to follow the first body, etc.
I tried using what maths I have but I can't seem to get it to calculate where the head just was or where the body in front of it just was.
here is my code:
#libraries
import turtle
import random
import math
#screen
the_screen = turtle.Screen()
the_screen.bgcolor("lightgreen")
the_screen.title("Catapillar")
#border
border_writer = turtle.Turtle()
border_writer.speed(0)
border_writer.color("green")
border_writer.penup()
border_writer.setposition(-275, -275)
border_writer.pendown()
border_writer.pensize(7)
for side in range(4):
border_writer.fd(550)
border_writer.lt(90)
border_writer.hideturtle()
#player
player = turtle.Turtle()
player.color("yellow")
player.shape("circle")
player.penup()
player.speed(0)
player.setposition(0,0)
player.setheading(0)
playerspeed = 2
#fruit
fruit = 1
fruit = turtle.Turtle()
fruit.color("red")
fruit.shape("circle")
fruit.penup()
fruit.speed(0)
fruit.shapesize(0.6, 0.6)
x = random.randint(-200, 200)
y = random.randint(100, 250)
fruit.setposition(x, y)
#moving and collision checker
def turnleft():
player.left(24.5)
def turnright():
player.right(24.5)
def increasespeed():
global playerspeed
playerspeed += 1
def isCollision(t1, t2):
distance = math.sqrt(math.pow(t1.xcor()-t2.xcor(), 2) + math.pow(t1.ycor()-t2.ycor(), 2))
if distance < 24:
return True
else:
return False
#making the tail(s) and hiding them
tail1 = turtle.Turtle()
tail1.hideturtle()
tail1.color("yellow")
tail1.shape("circle")
tail1.penup()
tail1.speed(0)
tail1.setposition(+700,700)
tail1.shapesize(0.6, 0.6)
tail1state = 'off'
#key presses
turtle.listen()
turtle.onkeypress(turnleft, "Left")
turtle.onkeypress(turnright, "Right")
turtle.onkeypress(increasespeed, "Up")
#main loop player always moves forward, out of bound set, reset fruit
#randomly when collided, create tail1...
while True:
player.forward(playerspeed)
#gameovers'
if (player.xcor() > 275) or (player.xcor() < -275):
playerspeed += 7
print("GAME OVER")
if (player.ycor() > 275) or (player.ycor() < -275):
playerspeed += 7
print("GAME OVER")
#collision check between fruit and head
if isCollision(player, fruit):
#resets the fruit, moves it randomly
fruit.hideturtle()
if tail1state == 'off':
uuu = player.xcor()
vvv = player.ycor()
tail1.setposition(uuu,vvv)
tail1.showturtle()
tail1state = 'on'
#reset the fruit
x = random.randint(-200, 200)
y = random.randint(-100, 250)
fruit.setposition(x, y)
fruit.showturtle()
#playerspeed +=1
If you have any idea on how you think I should approach it, please let me know what you think.
Thank you.
Since this comes up over and over (but effort to effect it is rarely shown) here's my minimal, generic, slithering around a screen effect that you should be able to adapt for your own purposes:
from turtle import Turtle, Screen
SNAKE_LENGTH = 10
SNAKE_SIZE = 15
WIDTH, HEIGHT = 375, 375
CURSOR_SIZE = 20
def slither():
segment = snake[-1].clone() if len(snake) < SNAKE_LENGTH else snake.pop(0)
screen.tracer(False) # segment.hideturtle()
segment.setposition(snake[-1].position())
segment.setheading(snake[-1].heading())
segment.forward(SNAKE_SIZE)
while not -WIDTH/2 < segment.xcor() < WIDTH/2 or not -HEIGHT/2 < segment.ycor() < HEIGHT/2:
segment.undo()
segment.right(95)
segment.forward(SNAKE_SIZE)
screen.tracer(True) # segment.showturtle()
snake.append(segment)
screen.ontimer(slither, 100)
boundary = Turtle(shape='square', visible=False)
boundary.shapesize(HEIGHT / CURSOR_SIZE, WIDTH / CURSOR_SIZE)
boundary.fillcolor("white")
boundary.stamp()
head = Turtle("circle")
head.shapesize(SNAKE_SIZE / CURSOR_SIZE)
head.penup()
snake = [head]
screen = Screen()
slither()
screen.exitonclick()