Sector Area and Arc Length

globals [end?]
turtles-own [
  out-counter
  around-counter
  outer-ring-counter
  around-angle-counter
  home-counter
  going-out?
  going-around?
  going-home?
  current-radius
  current-degrees
  fill-area?
]

to setup
  clear-all
  ask patches [
    set pcolor white
  ]
  reset-ticks
  create-turtles 1 [
    set color red
    facexy 1 0
    pen-down
    set pen-size 2
    set size 1.5
    set out-counter 0
    set around-angle-counter 0
    set around-counter 0
    set home-counter 0
    set going-out? true
    set going-around? false
    set going-home? false
    set fill-area? false
    set current-radius radius
    set current-degrees 0
    set end? false
  ]
end 

to go
  if end? [
    stop
  ]
  ;; handle the state of which way i should be going
  ask turtles [
    ;; determine the state
    if going-out? and out-counter >= current-radius [
      set going-out? false
      set out-counter 0
      set going-around? true
      set pen-size 5 set color blue
      left 90
    ]

    if going-around? and around-angle-counter > central-angle [
      set going-around? false
      set around-angle-counter 0
      set going-home? true
      set pen-size 2
      set color red
      left 90
    ]

    if going-home? and home-counter >= current-radius [
      set going-home? false
      set home-counter 0
      set fill-area? true
      set color green
      set pen-size 1
      setxy 0 0 ; for floating point errors i think
      left 180 - central-angle
    ]

    ;; based on the state, move accordingly
    if going-out? [
      forward 0.1
      set out-counter out-counter + 0.1
    ]

    if going-around? [
      forward 2 * pi * current-radius / 360
      left 1
      set outer-ring-counter outer-ring-counter + (2 * pi * current-radius / 360)
      ; set around-counter around-counter + (2 * pi * current-radius / 360) * 1
      set around-angle-counter around-angle-counter + 1
    ]
    if going-home? [
      forward 0.1
      set home-counter home-counter + 0.1
    ]
    if fill-area? [
      if current-degrees >= central-angle [
        set color red
        set end? true
      ]
      forward radius
      rt 180
      forward radius
      rt 180
      set around-counter around-counter + (1 / 360) * pi * radius * radius ; one step is around 15 pixels?
      print radius / 15
      lt 1
      set current-degrees current-degrees + 1
    ]
  ]
  tick
end 

to-report calc-sa
  report central-angle / 360 * pi * radius * radius
end 

to-report calc-al
  report central-angle / 360 * 2 * pi * radius
end 

to-report outer-ring-walked
  let dist 0
  ask turtle 0 [
    set dist outer-ring-counter
  ]
  report dist
end 

to-report circle-walked
  let dist 0
  ask turtle 0 [
    set dist around-counter
  ]
  report dist
end