Add code for repeating waves of enemies, adding intro animations so the enemies can 'fly in', and refactor entity to use a state machine system for more flexibility.

src/enemies.lua

@@ -0,0 +1,4 @@
+-- Convenience import for all enemy types
+
+import "enemy/ebi"
+import "enemy/ika"

src/enemy/ebi.lua

@@ -11,15 +11,11 @@ class("Ebi").extends(Entity)
 
 function Ebi:init()
    Ebi.super.init(self, gfx.image.new("images/ebi.png"), 5)
-
    self:setCollidesWithGroupsMask(0x3)
-   local dir = 1
+   self.type = 'ebi'
-   if math.random(2) == 1 then
-      dir = -1
 end
 
-   self.vector = geom.vector2D.new(0, dir)
+function Ebi:onReady()
-
    self.weaponTimer = playdate.timer.new(2500,
       function()
          local b = Bullet(2, 1)
@@ -30,8 +26,9 @@ function Ebi:init()
    self.weaponTimer.repeats = true
 end
 
-function Ebi:update()
+-- Ebi needs to bounce off the walls
-   local collisions = Ebi.super.update(self)
+function Ebi:runReady()
+   local collisions = Ebi.super.runReady(self)
    for i=1, #collisions, 1 do
       if collisions[i].other:getGroupMask() == 0x1 then
          self.vector.dy *= -1
@@ -39,7 +36,7 @@ function Ebi:update()
    end
 end
 
-function Ebi:delete()
+function Ebi:remove()
-   Ebi.super.delete(self)
+   Ebi.super.remove(self)
-   self.weaponTimer:remove()
+   if self.weaponTimer then self.weaponTimer:remove() end
 end

src/enemy/ika.lua

@@ -12,12 +12,15 @@ class("Ika").extends(Entity)
 
 function Ika:init(target)
    Ika.super.init(self, gfx.image.new("images/ika.png"), 25, 1)
-
+   self.target = target
    self:setCollidesWithGroupsMask(0x2)
+   self.type = 'ika'
+end
 
+function Ika:onReady()
    self.weaponTimer = playdate.timer.new(7000,
       function()
-         local b = Bullet(9, 20, self:calculateVector(target))
+         local b = Bullet(9, 20, self:calculateVector(self.target))
          b:moveTo(self.x - (self.width/2) - 1, self.y)
          b:add()
       end
@@ -26,9 +29,12 @@ function Ika:init(target)
 end
 
 function Ika:calculateVector(target)
-   local vec = geom.vector2D.new(0,0)
+   local vec = geom.point.new(target:getPosition()) -
-   vec.dx = target.x - self.x
+      geom.point.new(self:getPosition())
-   vec.dy = target.y - self.y
-
    return vec:normalized() * 3
 end
+
+function Ika:remove()
+   Ika.super.remove(self)
+   if self.weaponTimer then self.weaponTimer:remove() end
+end

src/entity.lua

@@ -2,6 +2,7 @@
 import "CoreLibs/object"
 import "CoreLibs/graphics"
 import "CoreLibs/sprites"
+import "statemachine"
 
 local gfx <const> = playdate.graphics
 local geom <const> = playdate.geometry
@@ -10,19 +11,39 @@ class("Entity").extends(gfx.sprite)
 
 function Entity:init(img, health, armor)
    Entity.super.init(self, img)
+   self.type = "entity"
    self.health = health or 10
    self.armor = armor or 0
+   self.introAnimator = nil
 
    -- movement direction, every update() the entity will move along this vector and return
    -- collision data to the subclass
    self.vector = geom.vector2D.new(0, 0)
-
    self:setCollideRect(0, 0, self:getSize())
 
    -- most entities will be enemies, so we configure this mask by default
    -- We don't set a collider mask because collision is a bit too variable
    -- (but we should always include 0x2 and handle player collisions)
    self:setGroupMask(0x4)
+
+   -- state machine mapping
+   -- this can be extended by subclasses if they need more states using
+   -- StateMachine:addState()
+   local states = {
+      ["INIT"] = {
+         main=self.runInit,
+         transition=self.onInit
+      },
+      ["INTRO"] = {
+         main=self.runIntro,
+         transition=self.onIntro,
+      },
+      ["READY"] = {
+         main=self.runReady,
+         transition=self.onReady,
+      },
+   }
+   self.fsm = StateMachine.new({self}, states)
 end
 
 function Entity:damage(amount)
@@ -31,16 +52,50 @@ function Entity:damage(amount)
    self.health = math.max(self.health - (amount - self.armor), 0)
 
    if self.health == 0 then
-      self:delete()
+      self:remove()
+   end
+end
+
+function Entity:add()
+   Entity.super.add(self)
+   if self.introAnimator then
+      self.fsm:changeState("INTRO")
+   else
+      self.fsm:changeState("READY")
    end
 end
 
 function Entity:update()
-   local collisions = select(3, self:moveWithCollisions(self.x + self.vector.dx, self.y + self.vector.dy))
+   -- update state machine
-   return collisions
+   self.fsm:execute()
 end
 
--- override this if you create timers
+-- State machine-controlled functions
-function Entity:delete()
+
-   self:remove()
+function Entity:onInit()
+  -- noop
+end
+
+function Entity:runInit()
+  -- noop
+end
+
+function Entity:onIntro()
+   -- noop
+end
+
+function Entity:runIntro()
+   if self.introAnimator and not self.introAnimator:ended() then
+      self:moveTo(self.introAnimator:currentValue())
+   else
+      self.fsm:changeState("READY")
+   end
+end
+
+function Entity:onReady()
+   -- noop
+end
+
+function Entity:runReady()
+   return select(3, self:moveWithCollisions(self.x + self.vector.dx, self.y + self.vector.dy))
 end

src/kani.lua

@@ -42,6 +42,7 @@ class("Kani").extends(Entity)
 function Kani:init(ui)
    Kani.super.init(self, gfx.image.new("images/kani.png"), 100)
 
+   self.type = 'kani'
    self:setGroupMask(0x2)
    self:setCollidesWithGroupsMask(0xd)
 
@@ -76,6 +77,8 @@ function Kani:init(ui)
       end,
       AButtonUp = function() self:fire() end,
    }
+
+   self.fsm:changeState("READY")
 end
 
 function Kani:chargeReserve(change)
@@ -141,8 +144,8 @@ function Kani:removeInputHandlers()
 end
 
 -- move that crab!
-function Kani:update()
+function Kani:runReady()
-   local collisions = Kani.super.update(self)
+   local collisions = Kani.super.runReady(self)
    for i=0, #collisions, 1 do
       -- handle player-triggered collisions
    end

src/main.lua

@@ -9,13 +9,15 @@ import "CoreLibs/graphics"
 import "CoreLibs/sprites"
 import "CoreLibs/timer"
 import "kani"
-import "enemy/ika"
+import "enemies"
-import "enemy/ebi"
+import "wave"
 
 local gfx <const> = playdate.graphics
+local geom <const> = playdate.geometry
 
 local player = nil
 local ui = nil
+local currentWave = nil
 
 function setup()
    ui = UI()
@@ -24,26 +26,8 @@ function setup()
    player:addInputHandlers()
    player:add()
    ui:add()
-
+   currentWave = newWave()
-   local enemy = Ika(player)
+   currentWave:add()
-   enemy:moveTo(350, 120)
-   enemy:add()
-
-   -- enemy = Ebi()
-   -- enemy:moveTo(270, 50)
-   -- enemy:add()
-
-   -- enemy = Ebi()
-   -- enemy:moveTo(280, 100)
-   -- enemy:add()
-
-   -- enemy = Ebi()
-   -- enemy:moveTo(290, 150)
-   -- enemy:add()
-
-   -- enemy = Ebi()
-   -- enemy:moveTo(300, 200)
-   -- enemy:add()
 
    makeWalls()
    drawBackground()
@@ -81,8 +65,52 @@ function drawBackground()
    )
 end
 
+-- Right now we only have a single wave and we repeat it forever
+function newWave()
+   wave = Wave.new()
+
+   local startPosition = geom.point.new(410,120)
+
+   local enemy = Ika(player)
+   enemy.introAnimator = gfx.animator.new(
+      10000,
+      startPosition,
+      geom.point.new(350,120)
+   )
+
+   wave:addEntity(enemy)
+
+   local y = 50
+   for x=270, 300, 10 do
+      local dir = 1
+      if math.random(2) == 1 then
+         dir = -1
+      end
+      local vector = geom.vector2D.new(0, dir)
+
+      enemy = Ebi()
+      enemy.vector = vector
+      enemy.introAnimator = gfx.animator.new(
+         5000,
+         startPosition,
+         geom.point.new(x,y)
+      )
+
+      wave:addEntity(enemy)
+
+      y += 50
+   end
+
+   return wave
+end
+
 function playdate.update()
    gfx.sprite.update()
+   if currentWave:update() then
+      -- fight forever lol
+      currentWave = newWave()
+      currentWave:add()
+   end
    playdate.timer.updateTimers()
 end
 

src/statemachine.lua

@@ -0,0 +1,47 @@
+-- A state machine
+import "CoreLibs/object"
+
+class("StateMachine").extends()
+
+function StateMachine.new(params, stateTable)
+   local fsm = StateMachine(params, stateTable)
+   return fsm
+end
+
+-- params is a table of parameters to always pass to the functions
+-- stateTable is a table of initial states. Entries should be of the form:
+--   name = {main=mainFunc, transition=transFunc}
+--   where mainFunc and transFunc are functions that should be executed in relation to the state.
+--   the State Machine will call mainFunc on execute()
+--   the State Machine will call transFunc when the state is entered
+function StateMachine:init(params, stateTable)
+   self.currentState = nil
+   self.parameters = params or {}
+   self.states = stateTable or {}
+end
+
+function StateMachine:addState(name, mainFunc, transFunc)
+   self.states[name] = {main=mainFunc, transition=transFunc}
+end
+
+-- execute the main function for the current state.
+-- returns true if the function was executed, false otherwise
+function StateMachine:execute()
+   if self.currentState == nil or not self.states[self.currentState] then
+      return false
+   end
+
+   self.states[self.currentState].main(table.unpack(self.parameters))
+   return true
+end
+
+-- change to the specified state. returns true if the state change is successful
+function StateMachine:changeState(state)
+   if not self.states[state] then return false end
+
+   self.currentState = state
+   if self.states[state].transition then
+      self.states[state].transition(table.unpack(self.parameters))
+   end
+   return true
+end

src/wave.lua

@@ -0,0 +1,64 @@
+-- A set of enemies that spawn as a group
+-- TODO: initialize waves from a file so we can define levels
+
+import "CoreLibs/object"
+import "entity"
+
+local gfx <const> = playdate.graphics
+local geom <const> = playdate.geometry
+
+class("Wave").extends()
+
+function Wave.new()
+   local w = Wave()
+   return w
+end
+
+function Wave:init()
+   Wave.super.init(self)
+   self.entities = {}
+end
+
+-- Adds an entity to the wave. Positions are playdate.geometry.point objects
+-- - position is where the entity should end up at the start of the combat sequence
+-- - vec is the enemy's starting vector
+-- - prePosition is the entity's start location for "flying in" animation
+-- - introDuration is the number of milliseconds the animation should take. Use this to control the fly-in speed
+function Wave:addEntity(entity)
+   table.insert(self.entities, entity)
+end
+
+-- Add all the sprites in the Wave to the global table
+-- Also initializes their intro animations
+function Wave:add()
+   for i=1, #self.entities, 1 do
+      self.entities[i]:add()
+   end
+end
+
+-- Call this every frame for an active Wave
+-- It will crawl the Entity list and remove any "dead"
+-- entities, and will return true to signal the wave end
+-- when all enemies are defeated
+function Wave:update()
+   local dead = {}
+   for i=1, #self.entities, 1 do
+      if self.entities[i].health == 0 then
+         table.insert(dead, i)
+         print(string.format("%d is dead", i))
+      end
+   end
+
+   -- Starting with the highest index to avoid renumbering errors,
+   -- we remove dead entities from the list
+   while #dead > 0 do
+      table.remove(self.entities, table.remove(dead))
+   end
+
+   if #self.entities == 0 then
+      return true
+   end
+
+   return false
+end
+