How to implement barriers to stop the player moving through walls

Quick note. This is for my A-Level NEA Programming Project. There are two main sections – One where a maze is generated and the user must navigate through it in a given time period, the time period is not currently implemented, and a second section where the user has to answer educational physics questions in order to get the best score. Questions are imported from a text file stored locally on my system. The user’s score is then exported to a local text file along with the date completed.

So far my program generates the maze and the user can move freely. The educational aspect works as intended.

# Imports
import pygame
import sys
import csv
import random
from datetime import date
# Initialising pygame
pygame.init()


# Setting parameters for commonly used colours
BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
BLUE = (0, 0, 255)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
# Creating a variable set to 'False' for the generation of the maze
done = False
# Setting variables for the size of the maze, how many columns and rows there will be
cols = 10
rows = 10
# Setting variables for the size of the window and the size of each individual part of the walls
width = 600
height = 600
wr = width/cols
hr = height/rows
# Initialising the 'screen' this is the surface within pygame that everything will be displayed upon
screen = pygame.display.set_mode([width, height])
screen_rect = screen.get_rect()
pygame.display.set_caption("Maze Generator")
# Creating a clock for the pygame module to run off of
clock = pygame.time.Clock()


# This is a class for the pathfinder section of the maze, it will allow the program to spot where needs to be visited
class Spot:
    def __init__(self, x, y):
        self.x = x
        self.y = y
        self.f = 0
        self.g = 0
        self.h = 0
        self.neighbors = []
        self.visited = False
        self.walls = [True, True, True, True]

    def show(self, color=BLACK):
        if self.walls[0]:
            pygame.draw.line(screen, color, [self.x*hr, self.y*wr],       [self.x*hr+hr, self.y*wr], 2)
        if self.walls[1]:
            pygame.draw.line(screen, color, [self.x*hr+hr, self.y*wr],    [self.x*hr+hr, self.y*wr + wr], 2)
        if self.walls[2]:
            pygame.draw.line(screen, color, [self.x*hr+hr, self.y*wr+wr], [self.x*hr, self.y*wr+wr], 2)
        if self.walls[3]:
            pygame.draw.line(screen, color, [self.x*hr, self.y*wr+wr],    [self.x*hr, self.y*wr], 2)

    def show_block(self, color):
        if self.visited:
            pygame.draw.rect(screen, color, [self.x*hr+2, self.y*wr+2, hr-2, wr-2])

    def add_neighbors(self):
        if self.x > 0:
            self.neighbors.append(grid[self.x - 1][self.y])
        if self.y > 0:
            self.neighbors.append(grid[self.x][self.y - 1])
        if self.x < rows - 1:
            self.neighbors.append(grid[self.x + 1][self.y])
        if self.y < cols - 1:
            self.neighbors.append(grid[self.x][self.y + 1])


grid = [[Spot(i, j) for j in range(cols)] for i in range(rows)]

for i in range(rows):
    for j in range(cols):
        grid[i][j].add_neighbors()

current = grid[0][0]
visited = [current]
completed = False


def breakwalls(a, b):
    if a.y == b.y and a.x > b.x:
        grid[b.x][b.y].walls[1] = False
        grid[a.x][a.y].walls[3] = False
    if a.y == b.y and a.x < b.x:
        grid[a.x][a.y].walls[1] = False
        grid[b.x][b.y].walls[3] = False
    if a.x == b.x and a.y < b.y:
        grid[b.x][b.y].walls[0] = False
        grid[a.x][a.y].walls[2] = False
    if a.x == b.x and a.y > b.y:
        grid[a.x][a.y].walls[0] = False
        grid[b.x][b.y].walls[2] = False


class Player:
    def __init__(self, x, y):
        self.rect = pygame.Rect(x, y, hr-2, wr-2)
        self.x = int(x)
        self.y = int(y)
        self.colour = (255, 0, 0)
        self.velX = 0
        self.velY = 0
        self.left_pressed = False
        self.right_pressed = False
        self.up_pressed = False
        self.down_pressed = False
        self.speed = 5

    def draw(self, win):
        pygame.draw.rect(win, self.colour, self.rect)

    def update(self):
        self.velX = 0
        self.velY = 0
        if self.left_pressed and not self.right_pressed:
            self.velX = -self.speed
        if self.right_pressed and not self.left_pressed:
            self.velX = self.speed
        if self.up_pressed and not self.down_pressed:
            self.velY = -self.speed
        if self.down_pressed and not self.up_pressed:
            self.velY = self.speed

        self.x += self.velX
        self.y += self.velY

        self.rect = pygame.Rect(self.x, self.y, hr-2, wr-2)


def readMyFiles():
    questionsAndAnswers = []
    correctAnswers = []

    with open('questions.txt', newline='') as f:
        reader = csv.reader(f, delimiter='\t')
        for row in reader:
            questionsAndAnswers.append(row)

    return questionsAndAnswers


def game(questions, answers, correctAnswers):
    score = 0
    counter = 0
    numberOfQuestions = len(questions)
    while not counter == numberOfQuestions:
        print(questions[counter])
        print(answers[counter])
        userAnswer = input('\nWhat is the correct answer?\n')
        if userAnswer == correctAnswers[counter]:
            print('Well done! That is correct.')
            score += 1
        else:
            print('Better luck next time, that is not correct.')
        counter += 1

    return score


def shuffleSplit(qna):
    random.shuffle(qna)
    questions = []
    answers = []
    correctAnswers = []
    for q in qna:
        questions.append(q[0])
        correctAnswers.append(q[1])
        del q[0]
        random.shuffle(q)
        answers.append(q)

    return (questions, answers, correctAnswers)


def exportScores(score, ):
    with open('scores.txt', mode='a') as scores:
        scores = csv.writer(scores, delimiter='\t')

        today = date.today()
        dateFormat = today.strftime("%d/%m/%Y")

        scores.writerow([dateFormat, score])


player = Player(2, 2)

while not done:
    clock.tick(60)
    screen.fill(BLACK)
    if not completed:
        grid[current.x][current.y].visited = True
        got_new = False
        temp = 10

        while not got_new and not completed:
            r = random.randint(0, len(current.neighbors)-1)
            Tempcurrent = current.neighbors[r]
            if not Tempcurrent.visited:
                visited.append(current)
                current = Tempcurrent
                got_new = True
            if temp == 0:
                temp = 10
                if len(visited) == 0:
                    completed = True
                    break
                else:
                    current = visited.pop()
            temp = temp - 1

        if not completed:
            breakwalls(current, visited[len(visited)-1])

        current.visited = True
        current.show_block(WHITE)

    for i in range(rows):
        for j in range(cols):
            grid[i][j].show(WHITE)
            # grid[i][j].show_block(BLUE)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            questionsAndAnswers = readMyFiles()
            questions, answers, correctAnswers = shuffleSplit(questionsAndAnswers)
            score = game(questions, answers, correctAnswers)
            exportScores(score)
            print('\nYour score is', str(score))
            sys.exit()
        if event.type == pygame.KEYDOWN and completed:
            if event.key == pygame.K_LEFT:
                player.left_pressed = True
            if event.key == pygame.K_RIGHT:
                player.right_pressed = True
            if event.key == pygame.K_UP:
                player.up_pressed = True
            if event.key == pygame.K_DOWN:
                player.down_pressed = True
        if event.type == pygame.KEYUP:
            if event.key == pygame.K_LEFT:
                player.left_pressed = False
            if event.key == pygame.K_RIGHT:
                player.right_pressed = False
            if event.key == pygame.K_UP:
                player.up_pressed = False
            if event.key == pygame.K_DOWN:
                player.down_pressed = False
    player.rect.clamp_ip(screen_rect)

    if player.x <= 2:
        player.left_pressed = False
        player.x = 2
    if player.y <= 2:
        player.up_pressed = False
        player.y = 2
    if player.x >= width-(wr-2):
        player.right_pressed = False
        player.x = width-(wr-2)
    if player.y >= height-(wr-2):
        player.down_pressed = False
        player.y = height-(wr-2)

    player.draw(screen)
    player.update()
    pygame.display.flip()

Where do I go from here to get to a point so that the walls act as physical barriers rather than just visual barriers? Currently, the maze is generated and the user can move throughout the screen. It always stays on the screen however I am not sure what the best way to implement the walls would be.

Here is Solutions:

We have many solutions to this problem, But we recommend you to use the first solution because it is tested & true solution that will 100% work for you.

Solution 1

Compute the bounding rectangle of the player and compute the grid indices of the corner points and and center point:

player_rect = pygame.Rect(player.x, player.y, wr-3, hr-3)
xC, yC = int(player_rect.centerx / wr), int(player_rect.centery / hr)
x0, y0 = int(player_rect.left / wr), int(player_rect.top / hr)
x1, y1 = int(player_rect.right / wr), int(player_rect.bottom / hr)

Restrict the movement dependent on the direction and walls. For instance:

if player.left_pressed and player_rect.x < xC*wr+2:
    if grid[xC][y0].walls[3] or grid[xC][y1].walls[3]:
        player.x = xC*wr+2
        player.left_pressed = False

Complete collision test:

How to implement barriers to stop the player moving through walls

while not done:
    # [...]

    player_rect = pygame.Rect(player.x, player.y, wr-3, hr-3)
    xC, yC = int(player_rect.centerx / wr), int(player_rect.centery / hr)
    x0, y0 = int(player_rect.left / wr), int(player_rect.top / hr)
    x1, y1 = int(player_rect.right / wr), int(player_rect.bottom / hr)

    if player.left_pressed and player_rect.x < xC*wr+2:
        if grid[xC][y0].walls[3] or grid[xC][y1].walls[3]:
            player.x = xC*wr+2
            player.left_pressed = False
        if player.y != yC*hr+2 and grid[x0][y0].walls[2]:
            player.x = xC*wr+2
            player.left_pressed = False
    
    if player.right_pressed and player_rect.x > xC*wr+2:
        if grid[xC][y0].walls[1] or grid[xC][y1].walls[1]:
            player.x = xC*wr+2
            player.right_pressed = False
        if player.y != yC*hr+2 and grid[x0+1][y0].walls[2]:
            player.x = xC*wr+2
            player.right_pressed = False

    if player.up_pressed and player_rect.y < yC*hr+2:
        if grid[x0][yC].walls[0] or grid[x1][yC].walls[0]:
            player.y = yC*hr+2
            player.up_pressed = False
        if player.x != xC*wr+2 and grid[x0][y0].walls[3]:
            player.y = yC*hr+2
            player.up_pressed = False

    if player.down_pressed and player_rect.y > yC*hr+2:
        if grid[x0][yC].walls[2] or grid[x1][yC].walls[2]:
            player.y = yC*hr+2
            player.down_pressed = False
        if player.x != xC*wr+2 and grid[x0][y0+1].walls[3]:
            player.y = yC*hr+2
            player.down_pressed = False

See also How do I prevent the player from moving through the walls in a maze?

Note: Use and implement solution 1 because this method fully tested our system.
Thank you 🙂

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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