Deplacement de plusieurs sprites à l'écran (SDL)

int game(ecran)
{
	SDL_Surface *perso2 = NULL;
	SDL_Rect pos2;
	SDL_Surface *perso = NULL;
	SDL_Rect pos;
	
	int i, j;
	int continuer = 1;
	SDL_Event event;

	
	SDL_Rect position, position2;

	perso = IMG_Load("mur.jpg");
	perso2 = IMG_Load("robot.gif");
	err = IMG_Load("err2.jpg");

	pos.x = 0;
	pos.y = 0;
	
	pos2.x = 300;
	pos2.y = 300;

	SDL_BlitSurface(perso, NULL, ecran, &pos);
	SDL_BlitSurface(perso2, NULL, ecran, &pos2);

SDL_EnableKeyRepeat(100, 100);

	while(continuer)
	{
		SDL_WaitEvent(&event);
		switch(event.type)
		{
		case SDL_QUIT:
			continuer = 0;
			break;

		case SDL_KEYDOWN:

			switch(event.key.keysym.sym)
			{
			case SDLK_UP:
				pos2.y++;
				break;
				
				

			case SDLK_DOWN:
				pos2.y--;
				break;
				

			case SDLK_RIGHT:
				pos2.x++;
				break;
				

			case SDLK_LEFT:
				pos2.x--;
				break;

				
			case SDLK_KP8:
				
				pos.y--;
				break;
				

			case SDLK_KP2:
				pos.y++;
				break;

			case SDLK_KP6:
				pos.x++;
				break;
				

			case SDLK_KP4:
				pos.x--;
				break;
			
			}
			
			
		}

		position.x = pos.x * BLOC;
		position.y = pos.y * BLOC;

		position2.x = pos2.x * BLOC;
		position2.y = pos2.y * BLOC;

		
		SDL_BlitSurface(perso2, NULL, ecran, &position2);
		SDL_BlitSurface(perso, NULL, ecran, &position);
				
		
		SDL_Flip(ecran);
	}

	SDL_EnableKeyRepeat (0, 0);


}