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,
 }