Message passing


message passing



local function landed(self) -- <2>
    label.set_text("#speech", "I'm there!")"bunny 2#script", "i'm there")

function on_message(self, message_id, message, sender)
    if message_id == hash("go to") then -- <1>
        label.set_text("#speech", "Ok...")
        go.animate(".", "position", go.PLAYBACK_ONCE_FORWARD, message.position, go.EASING_INOUTCUBIC, 1, 0, landed)

1. If someone sends us a "go to" message, set the speech label text and animate to the position supplied
   in the message data. At the end of animation, call the function `landed()`
2. This function is called when the position animation is completed. It sets the speech label text and then
   sends a message called "i'm there" to the component "script" in the "bunny 2" game object.


function init(self)".", "acquire_input_focus") -- <1>
    self.moving = false -- <2>

local function landed(self) -- <6>
    self.moving = false
    label.set_text("#speech", "Hey, go to the opposite side!")
    local pos = go.get_position()
    local opposite = vmath.vector3()
    opposite.x = 720 - pos.x
    opposite.y = 720 - pos.y"bunny 1#script", "go to", { position = opposite })

function on_message(self, message_id, message, sender)
    if message_id == hash("go to") then -- <5>
        self.moving = true
        label.set_text("#speech", "I'm going...")
        go.animate(".", "position", go.PLAYBACK_ONCE_FORWARD, message.position, go.EASING_INOUTCUBIC, 1.5, 0, landed)
    elseif message_id == hash("i'm there") then -- <7>
        label.set_text("#speech", "Great!")        

function on_input(self, action_id, action)
    if action_id == hash("touch") and action.pressed and not self.moving then -- <3>
        local pos = vmath.vector3(action.x, action.y, 0)"#", "go to", { position = pos }) -- <4>

1. Tell the engine that we want to receive input.
2. Store a flag in the current script component instance that tells us if the bunny is moving or not.
3. If user clicked and the bunny is not moving.
4. Send a message to this script component ("#" is shorthand for that) saying "go to" and the clicked position
   as part of the message data.
5. If a "go to" message is received, set the speech label text and then animate the position of the current 
   game object ("." is shorthand for that) to the position send in the message data. When the animation is
   done the function `landed()` is called.
6. When `landed()` is called on animation complete, set the label text, then calculate a position on the
   opposite of the screen and send a message called "go to" to the component "script" in the game object
   "bunny 1". Supplied with the message is the opposite position as message data.
7. If someone sends us a message called "i'm there" we react by just changing the speech label text.   

If you want to play with these examples, you can get the project on Github.

Do you want to see more examples? Why not write a few yourself and submit a pull request? We love contributions.