[copx]

Comment on the code:

As a Lua aficionado I hate to see stuff like this:

  Ball = {}
  Ball.__index = Ball

  function Ball.new (x, y)
    local table = {}
    setmetatable(table, Ball)
    table.x = x
    table.y = y
    return table
  end

Explicit setmetatable() call and manual __index setting? You can automate this and hide all the metatable magic = less code to write, less potential for bugs.

E.g. in my own Lua object system the above would be:

  Ball = Class()

  function Ball:Properties(x, y)
    return { x = x, y = y }
  end