Add Scrolling to a Platformer in Pygame

In platformer games, players navigate through levels while their position on the screen remains centered. This effect is achieved through scrolling, which allows the game world to move independently of the player's position.

Implementing Scrolling:

To implement scrolling in Pygame, use a Camera class that defines the offset between the game world and the player's position. This offset is then applied to the position of all game entities when they are drawn on the screen.

Creating the Camera Class:

class Camera:
    def __init__(self, camera_func, width, height):
        self.camera_func = camera_func
        self.state = Rect(0, 0, width, height)

    def apply(self, target):
        return target.rect.move(self.state.topleft)

    def update(self, target):
        self.state = self.camera_func(self.state, target.rect)

• camera_func: Determines how the camera follows the player.
• width, height: Size of the level in pixels.

Camera Functions:

There are various ways to implement the camera_func:

• Centering the Player:

  def simple_camera(camera, target_rect):
    l, t, _, _ = target_rect  # l = left, t = top
    _, _, w, h = camera      # w = width, h = height
    return Rect(-l   HALF_WIDTH, -t   HALF_HEIGHT, w, h)

• Maintaining Level Boundaries:

  def complex_camera(camera, target_rect):
    x = -target_rect.center[0]   WIN_WIDTH/2
    y = -target_rect.center[1]   WIN_HEIGHT/2
    camera.topleft  = (pygame.Vector2((x, y)) - pygame.Vector2(camera.topleft)) * 0.06 # add some smoothness coolnes
    camera.x = max(-(camera.width-WIN_WIDTH), min(0, camera.x))
    camera.y = max(-(camera.height-WIN_HEIGHT), min(0, camera.y))
    return camera

Applying Scrolling to Entities:

To apply scrolling, instantiate the Camera class and call its update and apply methods within the main game loop:

# Create the camera
camera = Camera(complex_camera, total_level_width, total_level_height)

# Update the camera
camera.update(player)

# Apply scrolling to all entities
for e in entities:
    screen.blit(e.image, camera.apply(e))

Additional Considerations:

• Use a LayeredUpdates subclass to handle camera-aware sprite groups.
• Adjust the camera movement speed and acceleration based on your game's needs.
• Handle level boundaries to prevent players from going off-screen.

By following these steps, you can implement scrolling in your Pygame platformer and create a smooth, engaging experience for players.