How to make Top-Down Racing game background move in opposite direction of car

Question

i am making a top down car racing game as project (i'm new to python) and i want to know how to make the track (that i have made a background) move, so that when the user's car is moving, the track is essentially moving in the opposite direction so it looks like you are progressing through the course of the circuit. (The camera is focused on the user's car)

Thanks

import math
import random

import pygame

pygame.mixer.pre_init(44100,16,2,4096)
pygame.init()
screen = pygame.display.set_mode((1280, 800))
rect = screen.get_rect()
clock = pygame.time.Clock()

#music
pygame.mixer.music.load("Wice.mp3")
pygame.mixer.music.set_volume(0.5)
pygame.mixer.music.play(-1)

WHITE = pygame.Color('white')
VEHICLE1 = pygame.Surface((40, 70), pygame.SRCALPHA)
VEHICLE1.fill((130, 180, 20))
#blitting car onto 'rectangle car'
VEHICLE1 = pygame.image.load("YellowLambo.png")
screen.blit(VEHICLE1,(0,0))
pygame.display.update()
VEHICLE2 = pygame.Surface((40, 70), pygame.SRCALPHA)
VEHICLE2.fill((200, 120, 20))
#blitting computer's car
VEHICLE2 = pygame.image.load("RedLambo.png")
screen.blit(VEHICLE2,(0,0))
pygame.display.update()
BACKGROUND = pygame.Surface((1280, 800))
BACKGROUND.fill((127, 69, 2))
BACKGROUND = pygame.image.load("track.png").convert()
screen.blit(BACKGROUND,(0,0))
pygame.display.update()


class Entity(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)


class VehicleSprite(Entity):
    MAX_FORWARD_SPEED = 10
    MAX_REVERSE_SPEED = 2
    ACCELERATION = 0.05
    TURN_SPEED = 0.000000000001

    def __init__(self, image, position):
        Entity.__init__(self)
        self.src_image = image
        self.image = image
        self.rect = self.image.get_rect(center=position)
        self.position = pygame.math.Vector2(position)
        self.velocity = pygame.math.Vector2(0, 0)
        self.speed = self.direction = 0
        self.k_left = self.k_right = self.k_down = self.k_up = 0

    def update(self, time):
        # SIMULATION
        self.speed += self.k_up + self.k_down
        # To clamp the speed.
        self.speed = max(-self.MAX_REVERSE_SPEED,
                         min(self.speed, self.MAX_FORWARD_SPEED))

        # Degrees sprite is facing (direction)
        self.direction += (self.k_right + self.k_left)
        rad = math.radians(self.direction)
        self.velocity.x = -self.speed*math.sin(rad)
        self.velocity.y = -self.speed*math.cos(rad)
        self.position += self.velocity
        self.image = pygame.transform.rotate(self.src_image, self.direction)
        self.rect = self.image.get_rect(center=self.position)


class Background(pygame.sprite.Sprite):

    def __init__(self, image, location):
        pygame.sprite.Sprite.__init__(self)
        self.image = image
        self.rect = self.image.get_rect(topleft=location)


def game_loop():
    background = Background(BACKGROUND, [0, 0])
    bike = VehicleSprite(VEHICLE1, rect.center)
    ball = VehicleSprite(VEHICLE2, rect.center)

    bike_group = pygame.sprite.Group(bike)
    ball_group = pygame.sprite.Group(ball)
    all_sprites = pygame.sprite.Group(bike_group, ball_group)

    camera = pygame.math.Vector2(0, 0)
    done = False

    while not done:
        time = clock.tick(60)

        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                done = True
            elif event.type == pygame.KEYDOWN:
                # Bike Input (Player 1)
                if event.key == pygame.K_d:
                    bike.k_right = -5
                elif event.key == pygame.K_a:
                    bike.k_left = 5
                elif event.key == pygame.K_w:
                    bike.k_up = 2
                elif event.key == pygame.K_s:
                    bike.k_down = -2

                elif event.key == pygame.K_ESCAPE:
                    done = True
            elif event.type == pygame.KEYUP:
                if event.key == pygame.K_d:
                    bike.k_right = 0
                elif event.key == pygame.K_a:
                    bike.k_left = 0
                elif event.key == pygame.K_w:
                    bike.k_up = 0
                elif event.key == pygame.K_s:
                    bike.k_down = 0

        camera -= bike.velocity

        all_sprites.update(time)

        screen.fill(WHITE)
        screen.blit(background.image, background.rect)

        for sprite in all_sprites:
            screen.blit(sprite.image, sprite.rect.topleft+camera)

        pygame.display.flip()


game_loop()
pygame.quit()

So, how doesn't your code achieve your requirements? See [mcve] — SiHa, May 25 '18 at 11:27

score 1 · Accepted Answer · answered May 25 '18 at 12:26

1

Just add the camera vector to the background.rect.topleft position as well:

screen.blit(background.image, background.rect.topleft+camera)

answered May 25 '18 at 12:26

skrx

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Oh right, thank you for the help! When i did this, the background was moving correctly, however the car was behind the background and couldn't be seen. What do i do to get the car to be on/over the track? – Y2J May 26 '18 at 09:11
You could use a [pygame.sprite.LayeredUpdates](http://www.pygame.org/docs/ref/sprite.html#pygame.sprite.LayeredUpdates) sprite group or blit the track and the cars separately or put the cars and track into separate groups. – skrx May 26 '18 at 09:32
Yeah i've upvoted but it won't show because im "less than 15 reputation", but it says the upvote was recorded. – Y2J May 26 '18 at 15:30

How to make Top-Down Racing game background move in opposite direction of car

1 Answers1