Make Ebi move, refactor bullet code to make more logic per-entity type.

src/kani.lua

@@ -20,13 +20,28 @@ local WEAPON_CHARGE_LOOKUP <const> = {
    [3]=50
 }
 
+-- size of bullet at each power level
+local POWER_SIZE_LOOKUP <const> = {
+   [1] = 2,
+   [2] = 4,
+   [3] = 6,
+   [4] = 10,
+}
+
+-- damage of bullet at each power level
+local POWER_DAMAGE_LOOKUP <const> = {
+   [1] = 1,
+   [2] = 3,
+   [3] = 5,
+   [4] = 10,
+}
+
 class("Kani").extends(Entity)
 
 function Kani:init(ui)
    local img = gfx.image.new("images/kani.png")
    Kani.super.init(self, img, 100)
 
-   self.vector = {x=0,y=0} -- movement direction
    self:setGroupMask(0x2)
    self:setCollidesWithGroupsMask(0xd)
 
@@ -96,7 +111,7 @@ function Kani:fire()
       return
    end
 
-   local bullet = Bullet(self.weaponPower)
+   local bullet = Bullet(POWER_SIZE_LOOKUP[self.weaponPower], POWER_DAMAGE_LOOKUP[self.weaponPower])
    bullet:moveTo(self.x+16, self.y)
    bullet:add()
    self.weaponPower = 0
@@ -122,7 +137,7 @@ end
 
 -- move that crab!
 function Kani:update()
-   local collisions = select(3, self:moveWithCollisions(self.x + self.vector.x, self.y + self.vector.y))
+   local collisions = Kani.super.update(self)
    for i=0, #collisions, 1 do
       -- handle player-triggered collisions
    end