MIHS Challenge 3 - solution

breed [leaders leader]
breed [followers follower]

to setup
  clear-all
  set-default-shape followers "bug"
  set-default-shape leaders "circle"
  create-followers 10
  ask followers 
  [
    setxy random-xcor random-ycor
  ]
  ;; the leader breed contains one turtle that is used to represent
  ;; a leader of the bugs (a circle)
  create-leaders 1 
  [
    set shape "circle"
    set color white
    set size 1.5
    hide-turtle
  ]
  reset-ticks
end 

to go
  move-followers
  move-leader
  tick
end 

to move-followers   ;; followers will face toward the leader, then move forward
  ask followers     ;; with a slight random wiggle
  [                 
    if not [hidden?] of leader 10  ;; checks to make sure the leader is visible
      [face leader 10]  ;; the leader is the 11th turtle created, so it has "who" # 10
                    ;; (the followers have "who" #'s 0-9).  This checks to see if the leader
                    ;; is present in the view
                    
    fd .5           ;; forward 1 step
    rt random 10    ;; turn right
    lt random 10    ;; turn left
  ]
end 

to move-leader      ;; this code makes the leader appear at the same position as the cursor
  ask leaders       ;; when the cursor is not inside the world, the leader is hidden
  [     
    setxy mouse-xcor mouse-ycor
    ;; only show the leader if the mouse pointer is
    ;; actually inside the view
    set hidden? not mouse-inside?  ;; "mouse-inside?" checks to see if the mouse is inside the world view
                                   ;; when the mouse is outside the world view window, 
                                   ;; the leader is toggled to hidden
  ]
end