Add some object-oriented sensibilities into this mess.

ball.lua

@@ -0,0 +1,44 @@
+import "pixie"
+
+class("Ball").extends(Pixie)
+
+function Ball:init(width, height, color, x, y)
+   Ball.super.init(self, width, height, color, x, y)
+   self.dirX = -1
+   self.dirY = 1
+   self.vector = {}
+   self.vector.x = -1
+   self.vector.y = 1
+   self.speed = 3
+   return self
+end
+
+function Ball:levelUp()
+   self.speed += 1
+end
+
+function Ball:move()
+   -- self:moveBy(self.vector.x * self.speed,
+   --             self.vector.y * self.speed)
+   self:moveBy(self.dirX * self.speed,
+               self.dirY * self.speed)
+end
+
+function Ball:setDirection(x, y)
+   x = x or self.dirX
+   y = y or self.dirY
+   self.dirX = x
+   self.dirY = y
+end
+
+function Ball:_normalizePosition()
+   local changeVector = Ball.super._normalizePosition(self)
+   if changeVector[1] ~= 0 then
+      -- self.vector.x = changeVector[1]
+      self.dirX = changeVector[1]
+   end
+   if changeVector[2] ~= 0 then
+      -- self.vector.y = changeVector[2]
+      self.dirY = changeVector[2]
+   end
+end