sharks-seals-fish-simple

breed[fish fishes]
breed[seals seal]
breed[sharks shark]

patches-own [ countdown]
turtles-own [ energy]

to setup
  clear-all
  reset-ticks

  ask patches [
    set pcolor one-of [green black]
    ifelse pcolor = green
        [set countdown algae-regrowth-time]
    [set countdown random algae-regrowth-time]]

  create-sharks initial-number-sharks
    [set shape "shark"
     set color blue
     set size 2
     setxy random-xcor random-ycor
    set energy random 10]
  create-seals initial-number-seals
     [set shape "seal"
      set color white
      set size 1.5
      setxy random-xcor random-ycor
    set energy random 10]
  create-fish initial-number-fish
       [set shape "fish 3"
      set color orange
      set size 1
      setxy random-xcor random-ycor
    set energy random 10]
end 

to go
  ask sharks
     [move
      eat-seals
      eat-fish
      death
      reproduce]
  tick
  ask seals [move
    eat-fish
    death
    reproduce]
  tick
  ask fish [move
    eat-algae
    death
    reproduce]
  tick
end 

to move
    rt random 50
    lt random 50
    fd 1
  set energy energy - 1
end 

to eat-seals
  let prey one-of seals-here
  if prey != nobody
    [ask prey [die]
      set energy energy + 1]
end 

to eat-fish
  let prey one-of fish-here
  if prey != nobody
    [ask prey [die]
      set energy energy + 1]
end 

to eat-algae
  if pcolor = green
      [set pcolor black
  set energy energy + 1]
end 

to death
  if energy <= 0 [die]
end 

to reproduce
  if energy > 0 and random-float 100 < 20
  [hatch 1 [ rt random-float 360 fd 1] set energy random 10]
end