Pygame, trying to erase sprite

Question

I am making a pygame app

With this app, I can place blue dot around the screen with mouse right click.

Middle mouse is supposed to erase all the dot, but this feature isn't working....

Any idea ?

# -*- coding: utf-8 -*-

import pygame
from pygame.locals import *


def func_circle(x,y):
    cercle=pygame.sprite.Sprite()
    pygame.sprite.Sprite.__init__(cercle)
    cercle.image=pygame.Surface((500,500))
    cercle.image.fill((0,0,0))
    cercle.image.set_colorkey((0,0,0))
    pygame.draw.circle(cercle.image,(0,0,255),(cercle.image.get_rect().centerx,cercle.image.get_rect().centery),25,0)
    cercle.image.convert_alpha()
    cercle.rect=cercle.image.get_rect()
    cercle.rect.centerx=x
    cercle.rect.centery=y    
    return cercle


pygame.init()
fenetre = pygame.display.set_mode((640, 480))

background = pygame.Surface(fenetre.get_size())
background = background.convert()
background.fill((250, 250, 250))

liste_des_sprites = pygame.sprite.LayeredUpdates()

continuer = 1
while continuer:
    for event in pygame.event.get():
        if event.type==MOUSEBUTTONDOWN and event.button==3:                        
            my_cicle=func_circle( event.pos[0],event.pos[1])           
            liste_des_sprites.add(my_cicle)

        if event.type==MOUSEBUTTONDOWN and event.button==2:
            print "trying to erase the blue dot"
            my_cicle.kill()
            liste_des_sprites.empty()

        if event.type==QUIT:
            continuer=0

    liste_des_sprites.draw(fenetre)


    pygame.display.update()

Answer 1

You have to clear screen - for example fill it with black color

fenetre.fill( (0,0,0) ) # clear screen

liste_des_sprites.draw(fenetre) # draw circles again

pygame.display.update() # send screen on monitor

or draw your background to remove old elements.

fenetre.blit( background, (0,0) ) # blit background to clear screen

liste_des_sprites.draw(fenetre) # draw circles again

pygame.display.update() # send screen on monitor