Day 020

Udemy Python Bootcamp Day 020

Snake Game

• Create a snake body
• Move the snake
• Control the snake
• Detect collision with food (Day 021)
• Create a scoreboard (Day 021)
• Detect collision with wall (Day 021)
• Detect collision with tail (Day 021)

Create a snake body

from turtle import Screen, Turtle

screen = Screen()
screen.setup(width=600, height=600)
screen.bgcolor("black")
screen.title("My Snake Game")

segment_1 = Turtle("square")
segment_1.color("white")

segment_2 = Turtle("square")
segment_2.color("white")
segment_2.goto(-20, 0)

segment_3 = Turtle("square")
segment_3.color("white")
segment_3.goto(-40, 0)

screen.exitonclick()

---

starting_position = [(0, 0), (-20, 0), (-40, 0)]

for position in starting_position:
    new_segment = Turtle("square")
    new_segment.color("white")
    new_segment.goto(position)

Move the Snake

from turtle import Screen, Turtle
import time

screen = Screen()
screen.setup(width=600, height=600)
screen.bgcolor("black")
screen.title("My Snake Game")
screen.tracer(0)

starting_position = [(0, 0), (-20, 0), (-40, 0)]

segments = []

for position in starting_position:
    new_segment = Turtle("square")
    new_segment.color("white")
    new_segment.penup()
    new_segment.goto(position)
    segments.append(new_segment)

game_is_on = True
while game_is_on:
    screen.update()
    time.sleep(0.1)

    for seg_num in range(len(segments) - 1, 0, -1):
        new_x = segments[seg_num - 1].xcor()
        new_y = segments[seg_num - 1].ycor()
        segments[seg_num].goto(new_x, new_y)
    segments[0].forward(20)

screen.exitonclick()

---

By the end of the whole project, we should end up with three classes; a snake class, a food class and a scoreboard.
And all of these classes will be in separate files, managing only one thing.

Move to OOP

snake.py

from turtle import Turtle
STARTING_POSITIONS = [(0, 0), (-20, 0), (-40, 0)]
MOVE_DISTANCE = 20

class Snake:

    def __init__(self):
        self.segments = []
        self.create_snake()

    def create_snake(self):
        for position in STARTING_POSITIONS:
            new_segment = Turtle("square")
            new_segment.color("white")
            new_segment.penup()
            new_segment.goto(position)
            self.segments.append(new_segment)

    def move(self):
        for seg_num in range(len(self.segments) - 1, 0, -1):
            new_x = self.segments[seg_num - 1].xcor()
            new_y = self.segments[seg_num - 1].ycor()
            self.segments[seg_num].goto(new_x, new_y)
        self.segments[0].forward(MOVE_DISTANCE)

main.py

from turtle import Screen, Turtle
from snake import Snake
import time

screen = Screen()
screen.setup(width=600, height=600)
screen.bgcolor("black")
screen.title("My Snake Game")
screen.tracer(0)

snake = Snake()

game_is_on = True
while game_is_on:
    screen.update()
    time.sleep(0.1)

    snake.move()

screen.exitonclick()

Control the Snake

snake.py

from turtle import Turtle
STARTING_POSITIONS = [(0, 0), (-20, 0), (-40, 0)]
MOVE_DISTANCE = 20


class Snake:

    def __init__(self):
        self.segments = []
        self.create_snake()
        self.head = self.segments[0]

    def create_snake(self):
        for position in STARTING_POSITIONS:
            new_segment = Turtle("square")
            new_segment.color("white")
            new_segment.penup()
            new_segment.goto(position)
            self.segments.append(new_segment)

    def move(self):
        for seg_num in range(len(self.segments) - 1, 0, -1):
            new_x = self.segments[seg_num - 1].xcor()
            new_y = self.segments[seg_num - 1].ycor()
            self.segments[seg_num].goto(new_x, new_y)
        self.head.forward(MOVE_DISTANCE)

    def up(self):
        self.head.setheading(90)

    def down(self):
        self.head.setheading(270)

    def left(self):
        self.head.setheading(180)

    def right(self):
        self.head.setheading(0)

main.py

from turtle import Screen, Turtle
from snake import Snake
import time

screen = Screen()
screen.setup(width=600, height=600)
screen.bgcolor("black")
screen.title("My Snake Game")
screen.tracer(0)

snake = Snake()

screen.listen()
screen.onkey(snake.up, "Up")
screen.onkey(snake.down, "Down")
screen.onkey(snake.left, "Left")
screen.onkey(snake.right, "Right")

game_is_on = True
while game_is_on:
    screen.update()
    time.sleep(0.1)

    snake.move()


screen.exitonclick()

---

Now be really careful here because it's not just self.head.heading, it's actually heading as a method because remember that the head of the snake is the first segment of our list of segments and each segment is a individual turtle.
The turtle has heading method which will give you a direction in terms of these 360-degree numbers, and then we can use that to check to see if it's equal to down. And if it is, then it's not allowed to go up.

snake.py

from turtle import Turtle
STARTING_POSITIONS = [(0, 0), (-20, 0), (-40, 0)]
MOVE_DISTANCE = 20
UP = 90
DOWN = 270
LEFT = 180
RIGHT = 0


class Snake:

    def __init__(self):
        self.segments = []
        self.create_snake()
        self.head = self.segments[0]

    def create_snake(self):
        for position in STARTING_POSITIONS:
            new_segment = Turtle("square")
            new_segment.color("white")
            new_segment.penup()
            new_segment.goto(position)
            self.segments.append(new_segment)

    def move(self):
        for seg_num in range(len(self.segments) - 1, 0, -1):
            new_x = self.segments[seg_num - 1].xcor()
            new_y = self.segments[seg_num - 1].ycor()
            self.segments[seg_num].goto(new_x, new_y)
        self.head.forward(MOVE_DISTANCE)

    def up(self):
        if self.head.heading() != DOWN:
            self.head.setheading(UP)

    def down(self):
        if self.head.heading() != UP:
            self.head.setheading(DOWN)

    def left(self):
        if self.head.heading() != RIGHT:
            self.head.setheading(LEFT)

    def right(self):
        if self.head.heading() != LEFT:
            self.head.setheading(RIGHT)

to be continued...

Programming is NOT Memorising.
What my job needs to be is to understand how things work.
Make sure that I understand how to use the code, when to code, how it works behind the scenes.