Pygame acceleration experiment

game.py

import pygame, sys, time, numpy as np
from pygame.locals import *

BACKGROUND_COLOR = (255, 255, 255)
CAR_COLOR = (0, 0, 255)
SCREEN_WIDTH, SCREEN_HEIGHT = 800, 600

class Car(object):
    def __init__(self):
        self.velocity = np.zeros(2)
        self.pos = np.zeros(2)
        self.size = (100, 100)

    def get_rect(self):
        return (self.pos[0], self.pos[1], self.size[0], self.size[1])

    def update(self, world_rect=None):
        self.pos += self.velocity

        if world_rect:
            min_x, min_y, max_x, max_y = world_rect
            max_x -= self.size[0]
            max_y -= self.size[1]

            self.pos[0] = max(self.pos[0], min_x)
            self.pos[0] = min(self.pos[0], max_x)

            self.pos[1] = max(self.pos[1], min_y)
            self.pos[1] = min(self.pos[1], max_y)

            if (self.pos[0] == min_x and self.velocity[0] < 0) or (self.pos[0] == max_x and self.velocity[0] > 0):
                self.velocity[0] = -self.velocity[0]

            if (self.pos[1] == min_y and self.velocity[1] < 0) or (self.pos[1] == max_y and self.velocity[1] > 0):
                self.velocity[1] = -self.velocity[1]


def main():
    pygame.init()
    car = Car()

    screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT), 0, 32)

    while True:
        for event in pygame.event.get():
            if event.type == QUIT:
                pygame.quit()
                sys.exit()

        pressed = pygame.key.get_pressed()
        
        if pressed[K_s]:
            car.velocity[1] += 0.001
        elif pressed[K_w]:
            car.velocity[1] -= 0.001

        if pressed[K_d]:
            car.velocity[0] += 0.001
        elif pressed[K_a]:
            car.velocity[0] -= 0.001
        
        car.velocity *= 0.9999

        car.update((0, 0, SCREEN_WIDTH, SCREEN_HEIGHT))

        screen.fill(BACKGROUND_COLOR)
        pygame.draw.rect(screen, CAR_COLOR, car.get_rect())
        pygame.display.update()

if __name__ == '__main__':
    main()