Untitled

globals [ age ]

;; Set two breeds of agents, one for the bugs and one for food

breed [ food a-food ]
breed [ bugs bug ]


bugs-own [
energy ;; The resource bugs will be depleting and refilling by moving and eating
speed ;; The "gene" of movement speed for each bug
vision ;; The "gene" that decides how far a bug can see
]

to setup
  clear-all
  reset-ticks
  setup-world
  setup-bugs
end 

to setup-world
  ask patches [
    set pcolor green + 2
  ]
end 

to setup-bugs

  ;; Creating the bugs and setting their initial states to numbers that, after trials, suits the model
  create-bugs 100 [
    set color 10
    set speed .5
    set energy 50
    set vision 3
     ]
  ask bugs [
    set shape "bug"
    setxy random-xcor random-ycor]
end 

to go

  ;; Two criteria for stop: One if no bugs are alive and one if any setting results in uncontrolled reproduction
  if not any? bugs [ stop ]
  if count bugs >= 2000 [ stop ]

  move-bug ;; Bugs move forward, change direction or towards food within their vision.
  eat-food ;; If standing on a patch where there is food, eats it
  eat-prey ;; If standing on a patch where there is prey, eats it
  check-death ;; Bugs check if their energy is zero, if yes they die
  reproduce ;; Bugs check if their energy is at or above the reproduction threshold. If yes they reproduce
            ;; with a 20% chance to mutate each gene and direction.
  regrow-food ;; Food grows at random places at a rate set in the interface

  tick
end 

to move-bug
  ask bugs [

    ;; Make bugs consider the nearest bug with half the size of self "prey". If there is no such bug within vision, set prey to the closest piece of food within vision.
    let prey min-one-of other ((bugs in-radius vision) with [ (size * 2) < [size] of myself ]) [distance myself]
    if prey = nobody [
       set prey min-one-of (food in-radius vision)  [distance myself]
    ]

    ;; If there is any prey, bug or food, within vision: Move towards it.
    ifelse prey != nobody [
      face prey
      ifelse distance prey < speed [
        move-to prey
      ][
        fd speed
      ]
    ]
    [
      ;; If no prey within vision, move forward at respective speed with a 20% chance of changing direction
      fd speed
      if random 100 < 20 [right random 360]
    ]

    ;; Set energy to decrease relative to current size and speed as well as the decided cost of each
    set energy energy - ((size * cost-of-size) * (speed * cost-of-speed))
  ]
end 

to eat-food

  ;; If there is any food at current position, eat it and set energy to increase by current food-value
  ask bugs [
  let prey one-of food-here
  if prey != nobody [
      ask prey [ die ]
      set energy energy + food-value ]
  ]
end 

to eat-prey
  ask bugs [

    ;; If there is any bugs with half the size of self at current position, eat it and set energy to increase by current prey-value
    let prey one-of other bugs-here with [ (size * 2) < [size] of myself ]
    if prey != nobody [
      ask prey [ die ]
      set energy energy + prey-value
    ]
  ]
end 

to check-death ;; If energy is at zero, the bug dies
  ask bugs [
    if energy <= 0 [ die ]
  ]
end 

to reproduce
  ask bugs [

    ;; If energy is above 100, decrease it by 50 and hatch a bug identical to self
    if energy > 100 [
      set energy energy - 50
        hatch 1 [

        ;; Each "gene" has a set chance of increasing or decreasing a set amount when being passed on to the offspring

        if random 100 < mutation-rate [
          ifelse random 100 < 50 [
            set speed speed * (1 + mutation-amount / 100) ][
            set speed speed * (1 - mutation-amount / 100)
          ]
        ]

        if random 100 < mutation-rate [
          ifelse random 100 < 50 [
            set size size * (1 + mutation-amount / 100) ][
            set size size * (1 - mutation-amount / 100)
          ]
        ]

        if random 100 < mutation-rate [
          ifelse random 100 < 50 [
            set vision vision * (1 + mutation-amount / 100) ][
            set vision vision * (1 - mutation-amount / 100)
          ]
        ]
    ]
   ]
  ]
end 

to regrow-food

  ;; Create food at the rate of food-growth at random places.

  if random 3 > 1 [
      create-food food-growth [

      setxy random-xcor random-ycor
      set shape "circle"
      set color red
      set size 0.5
    ]
  ]
end