:- consult('plnxt.pl').
 
start :-
	nxt_open,
	nxt_light_LED(activate),
	trigger_ground,
%	trigger_distance,
	write(ID),nl,
	nxt_go(300).

trigger_distance :-
        trigger_create(ID,check_distance,[go_back,trigger_distance]).

trigger_ground :-
	trigger_create(ID,check_ground,[go_back,trigger_ground]).

go_back :-
	nxt_stop,
	Angle is 120 + random(120),
	nxt_rotate(300,Angle),
	nxt_go(300).

check_ground :-
	nxt_light(Value,force),
	Value < 45.

check_distance :-
	nxt_ultrasonic(Distance,force),
	Distance < 20.

nxt_custom_stop :-
	trigger_killall,
	nxt_stop,
	nxt_light_LED(passivate),
	nxt_close.