Why Does My Pygame Ball Leave a Trail, and How Can I Fix It?

Moving the Ball in Pygame

In Pygame, when attempting to move an object, it's crucial to take a comprehensive approach by clearing the display in each frame with pygame.Surface.fill. This ensures that the previous state of the object is erased, allowing for smooth movement across the screen.

Upon further inspection of your code, it becomes apparent that you haven't incorporated this step into your animation loop. To rectify this, simply insert screen.fill(0) at the beginning of each iteration within the loop.

while True:
    # [...]

    screen.fill(0) # <---

    main.draw_elements()
    main.move_ball()
    main.ball.x_pos += main.ball.speed
    pygame.display.flip()

    # [...]

By implementing this modification, the ball's movement will no longer leave a trail behind, enabling it to move smoothly. In Pygame, the entire scene is redrawn with each frame, hence the reason for clearing the display at the inception of every frame. The typical application loop for Pygame involves:

1. Handling events with pygame.event.pump() or pygame.event.get().
2. Updating game states and object positions based on input events and time.
3. Clearing the entire display or drawing the background.
4. Drawing the entire scene (blitting all objects).
5. Updating the display with pygame.display.update() or pygame.display.flip().

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