MIHS-18P2 DT-JD

globals [ max-bird ]
breed [ sheep a-bird ]
breed [airplane airplane ]
turtles-own [ energy ]
patches-own [ countdown ]

to setup
  clear-all
  ifelse netlogo-web? [set max-bird 10000] [set max-airplane 30000]


  ifelse model-version = "bird-airplane-grass" [
    ask patches [
      set pcolor one-of [ blue white ]
      ifelse pcolor = blue
        [ set countdown grass-regrowth-time ]
      [ set countdown random grass-regrowth-time ]
    ]
  ]
  [
    ask patches [ set pcolor blue ]
  ]

  create-bird initial-number-bird
  [
    set shape  "bird"
    set color white
    set size 1.5
    set label-color blue - 2
    set energy random (2 * bird-gain-from-food)
    setxy random-xcor random-ycor
  ]

  create-airplane initial-number-airplane
  [
    set shape "airplane"
    set color black
    set size 2
    set energy random (2 * airplane-gain-from-food)
    setxy random-xcor random-ycor
  ]
  display-labels
  reset-ticks
end 

to go
  ;
  if not any? turtles [ stop ]
  ;
  if not any? airplane and count bird > max-bird [ user-message "The birds have inherited the sky" stop ]
  ask bird [
    move
    if model-version = "sheep-wolves-grass" [
      set energy energy - 1
      eat-grass
      death
    ]
    reproduce-bird
  ]
  ask airplane [
    move
    set energy energy - 1
    eat-bird
    death
    reproduce-airplane
  if model-version = "sheep-wolves-grass" [ ask patches [ grow-grass ] ]
  ;
  tick
  display-labels
end 

to move
  rt random 50
  lt random 50
  fd 1
end 

to eat-grass  ;
  if pcolor = green [
    set pcolor brown
    set energy energy + bird-gain-from-food  ; sheep gain energy by eating
  ]
end 

to reproduce-bird  ; sheep procedure
  if random-float 100 < bird-reproduce [
    set energy (energy / 2)
    hatch 1 [ rt random-float 360 fd 1 ]
  ]
end 

to reproduce-airplane
  if random-float 100 < airplane-reproduce [
    set energy (energy / 2)
    hatch 1 [ rt random-float 360 fd 1 ]
  ]
end 

to eat-bird
  let prey one-of bird-here
  if prey != nobody  [
    ask prey [ die ]
    set energy energy + airplane-gain-from-food
  ]
end 

to death
  if energy < 0 [ die ]
end 

to grow-grass
  if pcolor = white [
    ifelse countdown <= 0
      [ set pcolor blue
        set countdown grass-regrowth-time ]
      [ set countdown countdown - 1 ]
  ]
end