duckie :)

data/scripts/classes/duck.lua

@@ -0,0 +1,104 @@
+local Vector3 = require "types.vector3"
+local Signal = require "types.signal"
+
+local TEXTURE = "images/duckie.png"
+
+local States = {
+  IDLE = 1,
+  WANDER = 2,
+  CHASE = 3,
+}
+
+local WANDER_TIME = 1.0
+local IDLE_TIME = 1.0
+
+local Duck = {
+  position = {},
+  velocity = {},
+  direction = {},
+
+  target = nil,
+  state = States.IDLE,
+
+  wander_timer = 0,
+
+  speed = 0.02,
+  chase_speed = 0.04,
+  accel = 0.5,
+
+  STATES = States,
+
+  AteFeed = Signal.new()
+}
+
+Duck.__index = Duck
+
+function Duck.new(position)
+  local d = util.shallow_copy(Duck)
+  d.position = position
+  d.velocity = Vector3()
+  d.direction = Vector3(0, 0, -1):rotated(Vector3.UP, util.random_float(-math.pi, math.pi))
+
+  return setmetatable(d, Duck)
+end
+
+function Duck:tick(ctx)
+  if self.state == States.IDLE then
+    self:idle(ctx.frame_duration)
+  elseif self.state == States.WANDER then
+    self:wander(ctx.frame_duration)
+  elseif self.state == States.CHASE then
+    self:chase(ctx.frame_duration)
+  end
+  draw_billboard{position = self.position, size = {x = 0.4, y = 0.4}, texture = TEXTURE}
+end
+
+function Duck:idle(delta)
+  self.wander_timer = self.wander_timer + delta
+  if self.wander_timer >= IDLE_TIME then
+    self.state = States.WANDER
+    self.wander_timer = 0
+    self.direction = Vector3(0, 0, -1):rotated(Vector3.UP, math.random() * (math.pi * 2.0))
+    return
+  end
+end
+
+function Duck:wander(delta)
+  self.wander_timer = self.wander_timer + delta
+  if self.wander_timer >= WANDER_TIME then
+    self.state = States.IDLE
+    self.wander_timer = 0
+    return
+  end
+
+  local target_vel = self.direction * self.speed
+  self.velocity = self.velocity:lerp(target_vel, self.accel)
+  self.position = self.position + self.velocity
+end
+
+function Duck:chase(delta)
+  local hpos = self.position:horizontal()
+  local fhpos = self.target.position:horizontal()
+
+  local dist = hpos:distance_to(fhpos)
+  if dist <= 0.1 then
+    self.AteFeed:emit(self.target)
+    self.wander_timer = 0
+    self.state = States.IDLE
+    self.target = nil
+  else
+    local dir = self.position:horizontal():direction_to(self.target.position:horizontal())
+    local target_vel = dir * self.chase_speed
+    self.velocity = self.velocity:lerp(target_vel, self.accel)
+    self.position = self.position + self.velocity
+  end
+end
+
+function Duck:start_chase(feed)
+  if self.state == States.CHASE then return end
+  self.state = States.CHASE
+  self.target = feed
+  feed.occupied = true
+end
+
+return Duck

data/scripts/classes/feed.lua

@@ -7,6 +7,7 @@ local Feed = {
   direction = {},
   velocity = {},
   landed = false,
+  occupied = false,
 
   speed = 0.15,
 }

data/scripts/game.lua

@@ -1,12 +1,29 @@
 util = require "util"
 local player = require "classes.player"
 local Vector3 = require "types.vector3"
+local List = require "types.list"
 
 local Feed = require "classes.feed"
-local feed = {}
+local feed = List()
+
+local Duck = require "classes.duck"
+local ducks = List{Duck.new(Vector3(0, 0.4, 3))}
 
 local function create_feed(position, direction)
-  table.insert(feed, Feed.new(position, direction))
+  local f = Feed.new(position, direction)
+  feed:push(f)
+  local eligible_ducks = ducks:filter(
+    function (duck)
+      return duck.state ~= Duck.STATES.CHASE
+    end
+  )
+  if #eligible_ducks == 0 then return end
+  eligible_ducks[1]:start_chase(f)
+  f.occupied = true
+end
+
+local function delete_feed(f)
+  util.list_remove_value(feed, f)
 end
 
 -- called every frame, with constant delta time
@@ -18,6 +35,9 @@ function game_tick()
       capture = false,
     }
     player.ThrowPressed:connect(create_feed)
+    for _, v in ipairs(ducks) do
+      v.AteFeed:connect(delete_feed)
+    end
   end
 
   ctx.mouse_capture = ctx.udata.capture
@@ -27,7 +47,11 @@ function game_tick()
     ctx.udata.capture = not ctx.udata.capture
   end
 
-  for _, v in pairs(feed) do
+  for _, v in ipairs(feed) do
+    v:tick(ctx)
+  end
+
+  for _, v in ipairs(ducks) do
     v:tick(ctx)
   end
 

data/scripts/types/list.lua

@@ -0,0 +1,98 @@
+---@class List
+local List = {}
+
+local function reduce(list, f, init)
+  local acc = init
+  for i, v in ipairs(list) do
+    acc = f(v, acc, i)
+  end
+  return acc
+end
+
+local function filter(list, predicate)
+  return reduce(list, function(el, acc, i)
+    if predicate(el) then
+      table.insert(acc, el)
+    end
+    return acc
+  end, List.create{})
+end
+
+local function shallow_copy(t)
+  local t2 = {}
+  for k, v in ipairs(t) do
+    t2[k] = v
+  end
+  return t2
+end
+
+List.__index = List
+setmetatable(List, {
+  __call = function(self, ...)
+    local args = {...}
+    if #args == 0 then
+      return List.create()
+    end
+
+    if type(args[1]) == "table" then
+      return List.create(args[1])
+    end
+    return List.create(args)
+  end
+})
+
+---Constructs a new list from the given table.
+---@param from table?
+---@return List
+function List.create(from)
+  from = from or {}
+  local l = shallow_copy(from)
+  return setmetatable(l, List)
+end
+
+function List:__tostring()
+  local s = "List(" .. table.concat(self, ", ", 1, #self) .. ")"
+  return s
+end
+
+---Appends v to the end of the list.
+---@param v any
+function List:push(v)
+  table.insert(self, v)
+end
+
+---Removes the last element in the list and returns it.
+---@return any
+function List:pop()
+  return table.remove(self, #self)
+end
+
+---Reduce.
+---@param f function called with element, accumulator, index
+---@param init any initial value of accumulator
+---@return any
+function List:reduce(f, init)
+  return reduce(self, f, init)
+end
+
+---Returns a new List of all elements of this list that match the predicate function.
+---@param predicate function called with element
+---@return List
+function List:filter(predicate)
+  return filter(self, predicate)
+end
+
+---Returns the index of value, if it exists in the list, -1 otherwise.
+---@param value any
+---@return integer
+function List:find(value)
+  local idx = -1
+  for i, v in ipairs(self) do
+    if v == value then
+      idx = i
+      break
+    end
+  end
+  return idx
+end
+return List

data/scripts/util.lua

@@ -116,5 +116,13 @@ function util.clamp(v, min, max)
   return math.max(math.min(v, max), min)
 end
 
+---returns a random float in range (min, max)
+---@param min number
+---@param max number
+---@return number
+function util.random_float(min, max)
+  return min + math.random() * (max - min)
+end
+
 
 return util