Problem moving snake in a snake game using Turtle

Question

I'm trying to create an easier version of the snake game. Everything in the code looks ok for me but I can't make snake move as I want to. Can you help me why my code doesn't work? I don't understand why my code is not okay.

I searched for some similar games codes, but they all used time . and I couldn't understand the need for that.

Here is the code:

import turtle
import random


window = turtle.Screen()
window.screensize(600, 600)
window.title("Snake Eats Tomato Game")
window.bgcolor("skyblue")
window.tracer(0)


snake = turtle.Turtle()
snake.color("dark blue")
snake.shape("square")
snake.shapesize(1)
snake.speed(1)
snake.penup()
snake.goto(0, 100)
snake.direction = "stop"


def move():
    if snake.direction == "up":
        y = snake.ycor()
        snake.sety(y + 20)

    if snake.direction == "down":
        y = snake.ycor()
        snake.sety(y - 20)

    if snake.direction == "left":
        x = snake.xcor()
        snake.setx(x + 20)

    if snake.direction == "right":
        x = snake.xcor()
        snake.setx(x - 20)


point = 0

point_table = turtle.Turtle()
point_table.speed(0)
point_table.shape("square")
point_table.color("green")
point_table.penup()
point_table.hideturtle()
point_table.goto(-200, 200)
point_table.write(
    "POİNT: {}".format(point), align="center", font=("Courier", 25, "normal")
)


def go_left():
    if snake.direction != "right":
        snake.direction = "left"


def go_right():
    if snake.direction != "left":
        snake.direction = "right"


def go_up():
    if snake.direction != "down":
        snake.direction = "up"


def go_down():
    if snake.direction != "up":
        snake.direction = "down"


window.listen()
window.onkey(go_left, "Left")
window.onkey(go_right, "Right")
window.onkey(go_up, "Up")
window.onkey(go_down, "Down")


tomato = turtle.Turtle()
tomato.penup()
tomato.color("tomato")
tomato.shape("circle")
tomato.speed(0)
tomato.setposition(random.randint(-300, 300), random.randint(-300, 300))


while True:
    window.update()
    snake.forward(3)
    move()

    if snake.xcor() < -330 or snake.xcor() > 330:
        snake.right(90)
    if snake.ycor() < -330 or snake.ycor() > 330:
        snake.right(90)

    if snake.distance(tomato) < 20:
        point += 1
        point_table.clear()
        point_table.write(
            "PUAN: {}".format(point), align="center", font=("Courier", 25, "normal")
        )
        tomato.setposition(random.randint(-300, 300), random.randint(-300, 300))

Answer 1

There were some 'errors' in your code, I'll try to adres most of them, one by one:

---

1. Instead of always calling snake.forward(3) in the while True , change snake.direction = "stop" to snake.direction = "right" as the starting movement. This will keep the while loop clean

2. The go_left (etc) functions had an if to check the reversed way, I've removed those, just overwrite the direction

3. snake.xcor() < -330 these won't work, not every screen is 330 pixels. You'll need to use window.window_width() and window.window_height() to get the current window size, and use those values to detect the edges

4. WHen you detect an edge, don't do snake.right(90) , as this will instant move the snake. Just change the direction, to bounce it:

    if (curX < window_max_left): snake.direction = 'left' if (curX > window_max_right): snake.direction = 'right' if (curY > window_max_up): snake.direction = 'down' if (curY < window_max_down): snake.direction = 'up'

---

Applying those points, fixes the movement, and let the snake bounce of walls
_{* Please see the example recording below the code}

---

The final code looks like:

import turtle
import random


window = turtle.Screen()
window.screensize(600, 600)
window.title("Snake Eats Tomato Game")
window.bgcolor("skyblue")
window.tracer(0)


snake = turtle.Turtle()
snake.color("dark blue")
snake.shape("square")
snake.shapesize(1)
snake.speed(1)
snake.penup()
snake.goto(0, 100)
snake.direction = "right"


def move():
    if snake.direction == "up":
        y = snake.ycor()
        snake.sety(y + 10)

    if snake.direction == "down":
        y = snake.ycor()
        snake.sety(y - 10)

    if snake.direction == "left":
        x = snake.xcor()
        snake.setx(x + 10)

    if snake.direction == "right":
        x = snake.xcor()
        snake.setx(x - 10)


point = 0

point_table = turtle.Turtle()
point_table.speed(0)
point_table.shape("square")
point_table.color("green")
point_table.penup()
point_table.hideturtle()
point_table.goto(-200, 200)
point_table.write(
    "POİNT: {}".format(point), align="center", font=("Courier", 25, "normal")
)


def go_left():
    snake.direction = "left"


def go_right():
    snake.direction = "right"


def go_up():
    snake.direction = "up"


def go_down():
    snake.direction = "down"


window.listen()
window.onkey(go_left, "Left")
window.onkey(go_right, "Right")
window.onkey(go_up, "Up")
window.onkey(go_down, "Down")


tomato = turtle.Turtle()
tomato.penup()
tomato.color("tomato")
tomato.shape("circle")
tomato.speed(0)
tomato.setposition(random.randint(-300, 300), random.randint(-300, 300))

window_width = window.window_width()
window_height = window.window_height()

window_max_left = -abs(window_width / 2)
window_max_right = window_width / 2
window_max_down = -abs(window_height / 2)
window_max_up = window_height / 2


while True:

    curX = snake.xcor()
    curY = snake.ycor()

    if (curX < window_max_left):
        snake.direction = 'left'
    if (curX > window_max_right):
        snake.direction = 'right'
    if (curY > window_max_up):
        snake.direction = 'down'
    if (curY < window_max_down):
        snake.direction = 'up'

    if snake.distance(tomato) < 20:
        point += 1
        point_table.clear()
        point_table.write(
            "PUAN: {}".format(point), align="center", font=("Courier", 25, "normal")
        )
        tomato.setposition(random.randint(-300, 300), random.randint(-300, 300))

    move()
    window.update()

---

How it looked: