рекурсивные функции нужно мнение специалистов

procedure box(x1m,y1m,x2m,y2m:real;l:boolean);
var x1,x2,y1,y2:integer;
 begin
 if l=true then
 SetFillStyle(1,11)
 else
 setfillstyle(1,black);
  x1:=integer(round(x1m));
  x2:=integer(round(x2m));
  y1:=integer(round(y1m));
  y2:=integer(round(y2m));
 bar(x1,y1,x2,y2);
 end;

procedure build(x1,y1,x2,y2:real);
 begin

  box(x1,y1,x2,y2,true);

  box(x1,y1,x1+((x2-x1)/3),y1+((y2-y1)/3),false);
  box(x2-((x2-x1)/3),y1,x2,y1+((y2-y1)/3),false);
  box(x1,y2-((y2-y1)/3),x1+((x2-x1)/3),y2,false);
  box(x2-((x2-x1)/3),y2-((y2-y1)/3),x2,y2,false);

  box(x1-((x2-x1)/3),y1,x1,y1+((y2-y1)/3),true);
  box(x2-((x2-x1)/3),y1 -((y2-y1)/3),x2,y1,true);
  box(x1,y2,x1 +((x2-x1)/3),y2+((y2-y1)/3),true);
  box(x2,y2-((y2-y1)/3),x2+((x2-x1)/3),y2,true);


 build(x1-((x2-x1)/3),y1,x1,y1+((y2-y1)/3));
 build(x2-((x2-x1)/3),y1 -((y2-y1)/3),x2,y1);
 build(x1,y2,x1 +((x2-x1)/3),y2+((y2-y1)/3));
 build(x2,y2-((y2-y1)/3),x2+((x2-x1)/3),y2);
  end;

 build(x1-((x2-x1)/3),y1,x1,y1+((y2-y1)/3));
 build(x2-((x2-x1)/3),y1 -((y2-y1)/3),x2,y1);
 build(x1,y2,x1 +((x2-x1)/3),y2+((y2-y1)/3));
 build(x2,y2-((y2-y1)/3),x2+((x2-x1)/3),y2);

 build(x1-((x2-x1)/3),y1,x1,y1+((y2-y1)/3));