$app->add_event_handler(sub {
		my $event= shift;
		if($event->type == SDL_KEYDOWN){
			if($event-> key_sym == SDLK_UP){
				$player1->{v_y} = -2;
			}		
			elsif($event->key_sym == SDLK_DOWN){											
				$player1->{v_y} = 2;
			}
		}
		elsif($event->type == SDL_KEYUP){
			if($event->key_sym == SDLK_DOWN  || $event->key_sym == SDLK_UP){
			$player1->{v_y} = 0;
			}
		}
});