Turtles and Fish

globals [ max-Fishes ]  ; don't let Fishes population grow too large
; Fishes and wolves are both breeds of turtle.
breed [ Fishes Fish ]  ; Fishes is its own plural, so we use "a-Fishes" as the singular.
breed [ Wolves Wolf ]
turtles-own [ energy ]       ; both wolves and Fishes have energy
patches-own [ countdown ]

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

  ; Check model-version switch
  ; if we're not modeling grass, then the Fishes don't need to eat to survive
  ; otherwise the grass's state of growth and growing logic need to be set up
  ifelse model-version = "Fishes-Turtles-grass" [
    ask patches [
      set pcolor one-of [ 52 105 ]
      ifelse pcolor = 52
        [ set countdown grass-regrowth-time ]
      [ set countdown random grass-regrowth-time ] ; initialize grass regrowth clocks randomly for 105 patches
    ]
  ]
  [
    ask patches [ set pcolor Blue ]
  ]

  create-Fishes initial-number-Fishes  ; create the Fishes, then initialize their variables
  [
    set shape  "Fish"
    set color 45
    set size 2  ; easier to see
    set label-color blue - 2
    set energy random (2 * Fishes-gain-from-food)
    setxy random-xcor random-ycor
  ]

  create-wolves initial-number-Turtles  ; create the wolves, then initialize their variables
  [
    set shape "Turtle"
    set color 72
    set size 3  ; easier to see
    set energy random (2 * Turtles-gain-from-food)
    setxy random-xcor random-ycor
  ]
  display-labels
  reset-ticks
end 

to go
  ; stop the simulation of no wolves or Fishes
  if not any? turtles [ stop ]
  ; stop the model if there are no wolves and the number of Fishes gets very large
  if not any? Turtles and count Fishes > max-Fishes [ user-message "The Fish have inherited the earth" stop ]
  ask Fishes [
    move
    if model-version = "Fishes-Turtles-grass" [ ; in this version, Fishes eat grass, grass grows and it costs Fishes energy to move
      set energy energy - 1  ; deduct energy for Fishes only if running Fishes-wolf-grass model version
      eat-grass  ; Fishes eat grass only if running Fishes-wolf-grass model version
      death ; Fishes die from starvation only if running Fishes-wolf-grass model version
    ]
    reproduce-Fishes  ; Fishes reproduce at random rate governed by slider
  ]
  ask wolves [
    move
    set energy energy - 1  ; wolves lose energy as they move
    eat-Fishes ; wolves eat a Fishes on their patch
    death ; wolves die if our of energy
    reproduce-Turtles ; wolves reproduce at random rate governed by slider
  ]
  if model-version = "Fishes-Turtles-grass" [ ask patches [ grow-Grass ] ]
  ; set grass count patches with [pcolor = 52]
  tick
  display-labels
end 

to move  ; turtle procedure
  rt random 50
  lt random 50
  fd 1
end 

to eat-grass  ; Fishes procedure
  ; Fishes eat grass, turn the patch 105
  if pcolor = 52 [
    set pcolor 105
    set energy energy + Fishes-gain-from-food  ; Fishes gain energy by eating
  ]
end 

to reproduce-Fishes  ; Fishes procedure
  if random-float 100 < Fishes-reproduce [  ; throw "dice" to see if you will reproduce
    set energy (energy / 2)                ; divide energy between parent and offspring
    hatch 1 [ rt random-float 360 fd 1 ]   ; hatch an offspring and move it forward 1 step
  ]
end 

to reproduce-Turtles  ; wolf procedure
  if random-float 100 < Turtles-reproduce [  ; throw "dice" to see if you will reproduce
    set energy (energy / 2)               ; divide energy between parent and offspring
    hatch 1 [ rt random-float 360 fd 1 ]  ; hatch an offspring and move it forward 1 step
  ]
end 

to eat-Fishes  ; wolf procedure
  let prey one-of Fishes-here                    ; grab a random Fishes
  if prey != nobody  [                          ; did we get one?  if so,
    ask prey [ die ]                            ; kill it, and...
    set energy energy + Turtles-gain-from-food     ; get energy from eating
  ]
end 

to death  ; turtle procedure (i.e. both wolf nd Fishes procedure)
  ; when energy dips below zero, die
  if energy < 0 [ die ]
end 

to grow-grass  ; patch procedure
  ; countdown on 105 patches: if reach 0, grow some grass
  if pcolor = 105 [
    ifelse countdown <= 0
      [ set pcolor 52
        set countdown grass-regrowth-time ]
      [ set countdown countdown - 1 ]
  ]
end 

to-report grass
  ifelse model-version = "Fishes-Turtles-grass" [
    report patches with [pcolor = 52]
  ]
  [ report 0 ]
end 

to display-labels
  ask turtles [ set label "" ]
  if show-energy? [
    ask Turtles [ set label round energy ]
    if model-version = "Fishes-Turtles-grass" [ ask Fishes [ set label round energy ] ]
  ]
end 


; Copyright 1997 Uri Wilensky.
; See Info tab for full copyright and license.