basic_collision.py

import pygame

pygame.init()
screen = pygame.display.set_mode((1280, 720))
clock = pygame.time.Clock()
running = True
dt = 0

player_pos = pygame.Vector2(screen.get_width() / 2, screen.get_height() / 2)

while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
    
    screen.fill('black')
    
    pygame.draw.circle(screen, 'white', player_pos, 40)
    
    if ((player_pos.x < 40) or (player_pos.y > (screen.get_width() - 40)) or (player_pos.y < 40) or (player_pos.y > (screen.get_height() - 40))):
        player_pos.x = min(max(player_pos.x, 40), screen.get_width() - 40)
        player_pos.y = min(max(player_pos.y, 40), screen.get_height() - 40)
        
    keys = pygame.key.get_pressed()
    if keys[pygame.K_w]:
        player_pos.y -= 200 * dt
    if keys[pygame.K_s]:
        player_pos.y += 200 * dt
    if keys[pygame.K_a]:
        player_pos.x -= 200 * dt
    if keys[pygame.K_d]:
        player_pos.x += 200 * dt
    
    pygame.display.flip()
    
    dt = clock.tick(60) / 1000.0

pygame.quit()