cellular automaton robot ;
          /* robot CA */
type celltype = record 
	s: integer;
	dir: 0..4;
end;

const dimension = 2;
      distance = 1;
group neighbors4 = {*[0,1],*[0,-1],*[1,0],*[-1,0]};
group neighbors8 = {*[0,1],*[0,-1],*[1,0],*[-1,0],
		*[1,1],*[-1,1],*[1,-1],*[-1,-1]};
initial 
    [3,0] ~ (x = 2*lx/3 and y = 2*ly/3) ;
    [1,0] ~ x+1 = lx/2 and (y = ly/2 or y = ly/2+1) ;
    [2,0] ~ x = lx/3 and y = ly/3 ;
    [1,0] ~ x = lx/4+2 and y = ly/2+1;
    [1,0] ~ x = lx/2-2 and y = ly/4;
    [0,0] ~ true;
    
color   [255,0,0]   ~ *[0,0].s = 1;
        [255,255,0] ~ *[0,0].s = 2 or *[0,0].dir > 0;
 	[8**[0,0].s mod 255,8**[0,0].s mod 255,8* *[0,0].s mod 255] ~ *[0,0].s > 2;
	
var   c: celltype;
      temp : integer;
      
global t: integer;

rule global begin
	t := t+1;
end;

rule begin
    temp := 10000;
    for c in neighbors4 do
	if (c.s > 2 and c.s < temp) then
    	    temp := c.s;
		
    if *[0,0].s = 0 then 
    	if t < 3 and one (c in neighbors8: c.s = 1) then   *[0,0].s := 1
    	else
    	    if t > 3 and t < 50 and temp != 10000 then *[0,0].s := temp+1;
		
    if t >= 50 then begin
    	if *[0,0].s = 2 then begin
	    if *[0,1].s = temp then *[0,0].dir := 1;
	    if *[0,-1].s = temp then *[0,0].dir := 2;
	    if *[1,0].s = temp then *[0,0].dir := 3;
	    if *[-1,0].s = temp then *[0,0].dir := 4;
	end;
    	if *[0,0].s > 3 then begin
    	    if *[0,-1].dir = 1  or
	     *[0,1].dir = 2 or 
	     *[-1,0].dir = 3 or
	     *[1,0].dir = 4 then 
	     	*[0,0].s := 2;
	    
		
	end;  
	if *[0,0].dir > 0 then *[0,0].s := 0;
    end;
end;