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Game object API documentation

version 1.2.115

Functions, core hooks, messages and constants for manipulation of game objects. The "go" namespace is accessible from game object script files.

Functions

final

called when a script component is finalized

go.animate

animates a named property of the specified game object or component

go.cancel_animations

cancels all animations of the named property of the specified game object or component

go.delete

delete one or more game object instances

go.get

gets a named property of the specified game object or component

go.get_id

gets the id of an instance

go.get_position

gets the position of a game object instance

go.get_rotation

gets the rotation of the game object instance

go.get_scale

gets the 3D scale factor of the game object instance

go.get_scale_uniform

gets the uniform scale factor of the game object instance

go.get_world_position

gets the game object instance world position

go.get_world_rotation

gets the game object instance world rotation

go.get_world_scale

gets the game object instance world 3D scale factor

go.get_world_scale_uniform

gets the uniform game object instance world scale factor

go.property

define a property for the script

go.set

sets a named property of the specified game object or component

go.set_position

sets the position of the game object instance

go.set_rotation

sets the rotation of the game object instance

go.set_scale

sets the scale factor of the game object instance

init

called when a script component is initialized

on_input

called when user input is received

on_message

called when a message has been sent to the script component

on_reload

called when the script component is reloaded

update

called every frame to update the script component

Messages

Constants

go.EASING_INBACK

in-back

go.EASING_INBOUNCE

in-bounce

go.EASING_INCIRC

in-circlic

go.EASING_INCUBIC

in-cubic

go.EASING_INELASTIC

in-elastic

go.EASING_INEXPO

in-exponential

go.EASING_INOUTBACK

in-out-back

go.EASING_INOUTBOUNCE

in-out-bounce

go.EASING_INOUTCIRC

in-out-circlic

go.EASING_INOUTCUBIC

in-out-cubic

go.EASING_INOUTELASTIC

in-out-elastic

go.EASING_INOUTEXPO

in-out-exponential

go.EASING_INOUTQUAD

in-out-quadratic

go.EASING_INOUTQUART

in-out-quartic

go.EASING_INOUTQUINT

in-out-quintic

go.EASING_INOUTSINE

in-out-sine

go.EASING_INQUAD

in-quadratic

go.EASING_INQUART

in-quartic

go.EASING_INQUINT

in-quintic

go.EASING_INSINE

in-sine

go.EASING_LINEAR

linear interpolation

go.EASING_OUTBACK

out-back

go.EASING_OUTBOUNCE

out-bounce

go.EASING_OUTCIRC

out-circlic

go.EASING_OUTCUBIC

out-cubic

go.EASING_OUTELASTIC

out-elastic

go.EASING_OUTEXPO

out-exponential

go.EASING_OUTINBACK

out-in-back

go.EASING_OUTINBOUNCE

out-in-bounce

go.EASING_OUTINCIRC

out-in-circlic

go.EASING_OUTINCUBIC

out-in-cubic

go.EASING_OUTINELASTIC

out-in-elastic

go.EASING_OUTINEXPO

out-in-exponential

go.EASING_OUTINQUAD

out-in-quadratic

go.EASING_OUTINQUART

out-in-quartic

go.EASING_OUTINQUINT

out-in-quintic

go.EASING_OUTINSINE

out-in-sine

go.EASING_OUTQUAD

out-quadratic

go.EASING_OUTQUART

out-quartic

go.EASING_OUTQUINT

out-quintic

go.EASING_OUTSINE

out-sine

go.PLAYBACK_LOOP_BACKWARD

loop backward

go.PLAYBACK_LOOP_FORWARD

loop forward

go.PLAYBACK_LOOP_PINGPONG

ping pong loop

go.PLAYBACK_NONE

no playback

go.PLAYBACK_ONCE_BACKWARD

once backward

go.PLAYBACK_ONCE_FORWARD

once forward

go.PLAYBACK_ONCE_PINGPONG

once ping pong

Properties

Functions

final

final(self)

This is a callback-function, which is called by the engine when a script component is finalized (destroyed). It can be used to e.g. take some last action, report the finalization to other game object instances, delete spawned objects or release user input focus (see release_input_focus).

Parameters

self

object reference to the script state to be used for storing data

self

object reference to the script state to be used for storing data

Examples

function final(self)
    -- report finalization
    msg.post("my_friend_instance", "im_dead", {my_stats = self.some_value})
end

go.animate

go.animate(url, property, playback, to, easing, duration, [delay], [complete_function])

This is only supported for numerical properties. If the node property is already being animated, that animation will be canceled and replaced by the new one.

If a complete_function (lua function) is specified, that function will be called when the animation has completed. By starting a new animation in that function, several animations can be sequenced together. See the examples for more information.

If you call go.animate() from a game object's final() function, any passed complete_function will be ignored and never called upon animation completion.

See the properties guide for which properties can be animated and the animation guide for how to animate them.

Parameters

url

string | hash | url url of the game object or component having the property

property

string | hash id of the property to animate

playback

constant playback mode of the animation

  • go.PLAYBACK_ONCE_FORWARD
  • go.PLAYBACK_ONCE_BACKWARD
  • go.PLAYBACK_ONCE_PINGPONG
  • go.PLAYBACK_LOOP_FORWARD
  • go.PLAYBACK_LOOP_BACKWARD
  • go.PLAYBACK_LOOP_PINGPONG
to

number | vector3 | vector4 | quaternion target property value

easing

constant | vector easing to use during animation. Either specify a constant, see the animation guide for a complete list, or a vmath.vector with a curve

duration

number duration of the animation in seconds

[delay]

number delay before the animation starts in seconds

[complete_function]

function(self, url, property) optional function to call when the animation has completed

self

object The current object.

url

url The game object or component instance for which the property is animated.

property

hash The id of the animated property.

url

string | hash | url url of the game object or component having the property

property

string | hash id of the property to animate

playback

constant playback mode of the animation

  • go.PLAYBACK_ONCE_FORWARD
  • go.PLAYBACK_ONCE_BACKWARD
  • go.PLAYBACK_ONCE_PINGPONG
  • go.PLAYBACK_LOOP_FORWARD
  • go.PLAYBACK_LOOP_BACKWARD
  • go.PLAYBACK_LOOP_PINGPONG
to

number | vector3 | vector4 | quaternion target property value

easing

constant | vector easing to use during animation. Either specify a constant, see the animation guide for a complete list, or a vmath.vector with a curve

duration

number duration of the animation in seconds

[delay]

number delay before the animation starts in seconds

[complete_function]

function(self, url, property) optional function to call when the animation has completed

self

object The current object.

url

url The game object or component instance for which the property is animated.

property

hash The id of the animated property.

Examples

Animate the position of a game object to x = 10 during 1 second, then y = 20 during 1 second:

local function x_done(self, url, property)
    go.animate(go.get_id(), "position.y", go.PLAYBACK_ONCE_FORWARD, 20, go.EASING_LINEAR, 1)
end

function init(self)
    go.animate(go.get_id(), "position.x", go.PLAYBACK_ONCE_FORWARD, 10, go.EASING_LINEAR, 1, 0, x_done)
end

Animate the y position of a game object using a crazy custom easing curve:

local values = { 0, 0, 0, 0, 0, 0, 0, 0,
                 1, 1, 1, 1, 1, 1, 1, 1,
                 0, 0, 0, 0, 0, 0, 0, 0,
                 1, 1, 1, 1, 1, 1, 1, 1,
                 0, 0, 0, 0, 0, 0, 0, 0,
                 1, 1, 1, 1, 1, 1, 1, 1,
                 0, 0, 0, 0, 0, 0, 0, 0,
                 1, 1, 1, 1, 1, 1, 1, 1 }
local vec = vmath.vector(values)
go.animate("go", "position.y", go.PLAYBACK_LOOP_PINGPONG, 100, vec, 2.0)

go.cancel_animations

go.cancel_animations(url, property)

By calling this function, all stored animations of the given property will be canceled.

See the properties guide for which properties can be animated and the animation guide for how to animate them.

Parameters

url

string | hash | url url of the game object or component having the property

property

string | hash ide of the property to animate

url

string | hash | url url of the game object or component having the property

property

string | hash ide of the property to animate

Examples

Cancel the animation of the position of a game object:

go.cancel_animations(go.get_id(), "position")

go.delete

go.delete([id], [recursive])

Delete one or more game objects identified by id.

Parameters

[id]

string | hash | url | table optional id or table of id's of the instance(s) to delete, the instance of the calling script is deleted by default

[recursive]

boolean optional boolean, set to true to recursively delete child hiearchy in child to parent order

[id]

string | hash | url | table optional id or table of id's of the instance(s) to delete, the instance of the calling script is deleted by default

[recursive]

boolean optional boolean, set to true to recursively delete child hiearchy in child to parent order

Examples

This example demonstrates how to delete game objects

-- Delete the script game object
go.delete()
-- Delete a game object with the id "my_game_object".
local id = go.get_id("my_game_object") -- retrieve the id of the game object to be deleted
go.delete(id)
-- Delete a list of game objects.
local ids = { hash("/my_object_1"), hash("/my_object_2"), hash("/my_object_3") }
go.delete(ids)

This example demonstrates how to delete a game objects and their children (child to parent order)

-- Delete the script game object and it's children
go.delete(true)
-- Delete a game object with the id "my_game_object" and it's children.
local id = go.get_id("my_game_object") -- retrieve the id of the game object to be deleted
go.delete(id, true)
-- Delete a list of game objects and their children.
local ids = { hash("/my_object_1"), hash("/my_object_2"), hash("/my_object_3") }
go.delete(ids, true)

go.get

go.get(url, property)

Parameters

url

string | hash | url url of the game object or component having the property

property

string | hash id of the property to retrieve

url

string | hash | url url of the game object or component having the property

property

string | hash id of the property to retrieve

Returns

value

any the value of the specified property

value

any the value of the specified property

Examples

Get a property "speed" from a script "player", the property must be declared in the player-script:

go.property("speed", 50)

Then in the calling script (assumed to belong to the same game object, but does not have to):

local speed = go.get("#player", "speed")

go.get_id

go.get_id([path])

Returns or constructs an instance identifier. The instance id is a hash of the absolute path to the instance.

  • If path is specified, it can either be absolute or relative to the instance of the calling script.
  • If path is not specified, the id of the game object instance the script is attached to will be returned.

Parameters

[path]

string path of the instance for which to return the id

[path]

string path of the instance for which to return the id

Returns

id

hash instance id

id

hash instance id

Examples

For the instance with path /my_sub_collection/my_instance, the following calls are equivalent:

local id = go.get_id() -- no path, defaults to the instance containing the calling script
print(id) --> hash: [/my_sub_collection/my_instance]

local id = go.get_id("/my_sub_collection/my_instance") -- absolute path
print(id) --> hash: [/my_sub_collection/my_instance]

local id = go.get_id("my_instance") -- relative path
print(id) --> hash: [/my_sub_collection/my_instance]

go.get_position

go.get_position([id])

The position is relative the parent (if any). Use go.get_world_position to retrieve the global world position.

Parameters

[id]

string | hash | url optional id of the game object instance to get the position for, by default the instance of the calling script

[id]

string | hash | url optional id of the game object instance to get the position for, by default the instance of the calling script

Returns

position

vector3 instance position

position

vector3 instance position

Examples

Get the position of the game object instance the script is attached to:

local p = go.get_position()

Get the position of another game object instance "my_gameobject":

local pos = go.get_position("my_gameobject")

go.get_rotation

go.get_rotation([id])

The rotation is relative to the parent (if any). Use go.get_world_rotation to retrieve the global world position.

Parameters

[id]

string | hash | url optional id of the game object instance to get the rotation for, by default the instance of the calling script

[id]

string | hash | url optional id of the game object instance to get the rotation for, by default the instance of the calling script

Returns

rotation

quaternion instance rotation

rotation

quaternion instance rotation

Examples

Get the rotation of the game object instance the script is attached to:

local r = go.get_rotation()

Get the rotation of another game object instance "x":

local r = go.get_rotation("x")

go.get_scale

go.get_scale([id])

The scale is relative the parent (if any). Use go.get_world_scale to retrieve the global world 3D scale factor.

Parameters

[id]

string | hash | url optional id of the game object instance to get the scale for, by default the instance of the calling script

[id]

string | hash | url optional id of the game object instance to get the scale for, by default the instance of the calling script

Returns

scale

vector3 instance scale factor

scale

vector3 instance scale factor

Examples

Get the scale of the game object instance the script is attached to:

local s = go.get_scale()

Get the scale of another game object instance "x":

local s = go.get_scale("x")

go.get_scale_uniform

go.get_scale_uniform([id])

The uniform scale is relative the parent (if any). If the underlying scale vector is non-uniform the min element of the vector is returned as the uniform scale factor.

Parameters

[id]

string | hash | url optional id of the game object instance to get the uniform scale for, by default the instance of the calling script

[id]

string | hash | url optional id of the game object instance to get the uniform scale for, by default the instance of the calling script

Returns

scale

number uniform instance scale factor

scale

number uniform instance scale factor

Examples

Get the scale of the game object instance the script is attached to:

local s = go.get_scale_uniform()

Get the uniform scale of another game object instance "x":

local s = go.get_scale_uniform("x")

go.get_world_position

go.get_world_position([id])

Use go.get_position to retrieve the position relative to the parent.

Parameters

[id]

string | hash | url optional id of the game object instance to get the world position for, by default the instance of the calling script

[id]

string | hash | url optional id of the game object instance to get the world position for, by default the instance of the calling script

Returns

position

vector3 instance world position

position

vector3 instance world position

Examples

Get the world position of the game object instance the script is attached to:

local p = go.get_world_position()

Get the world position of another game object instance with id "x":

local p = go.get_world_position("x")

go.get_world_rotation

go.get_world_rotation([id])

Use go.get_rotation to retrieve the rotation relative to the parent.

Parameters

[id]

string | hash | url optional id of the game object instance to get the world rotation for, by default the instance of the calling script

[id]

string | hash | url optional id of the game object instance to get the world rotation for, by default the instance of the calling script

Returns

rotation

quaternion instance world rotation

rotation

quaternion instance world rotation

Examples

Get the world rotation of the game object instance the script is attached to:

local r = go.get_world_rotation()

Get the world rotation of another game object instance with id "x":

local r = go.get_world_rotation("x")

go.get_world_scale

go.get_world_scale([id])

Use go.get_scale to retrieve the 3D scale factor relative to the parent. This vector is derived by decomposing the transformation matrix and should be used with care. For most cases it should be fine to use go.get_world_scale_uniform instead.

Parameters

[id]

string | hash | url optional id of the game object instance to get the world scale for, by default the instance of the calling script

[id]

string | hash | url optional id of the game object instance to get the world scale for, by default the instance of the calling script

Returns

scale

vector3 instance world 3D scale factor

scale

vector3 instance world 3D scale factor

Examples

Get the world 3D scale of the game object instance the script is attached to:

local s = go.get_world_scale()

Get the world scale of another game object instance "x":

local s = go.get_world_scale("x")

go.get_world_scale_uniform

go.get_world_scale_uniform([id])

Use go.get_scale_uniform to retrieve the scale factor relative to the parent.

Parameters

[id]

string | hash | url optional id of the game object instance to get the world scale for, by default the instance of the calling script

[id]

string | hash | url optional id of the game object instance to get the world scale for, by default the instance of the calling script

Returns

scale

number instance world scale factor

scale

number instance world scale factor

Examples

Get the world scale of the game object instance the script is attached to:

local s = go.get_world_scale_uniform()

Get the world scale of another game object instance with id "x":

local s = go.get_world_scale_uniform("x")

go.property

go.property(name, value)

This function defines a property which can then be used in the script through the self-reference. The properties defined this way are automatically exposed in the editor in game objects and collections which use the script. Note that you can only use this function outside any callback-functions like init and update.

Parameters

name

string the id of the property

value

number | hash | url | vector3 | vector4 | quaternion default value of the property. In the case of a url, only the empty constructor msg.url() is allowed

name

string the id of the property

value

number | hash | url | vector3 | vector4 | quaternion default value of the property. In the case of a url, only the empty constructor msg.url() is allowed

Examples

This example demonstrates how to define a property called "health" in a script. The health is decreased whenever someone sends a message called "take_damage" to the script.

go.property("health", 100)

function init(self)
    -- prints 100 to the output
    print(self.health)
end

function on_message(self, message_id, message, sender)
    if message_id == hash("take_damage") then
        self.health = self.health - message.damage
        print("Ouch! My health is now: " .. self.health)
    end
end

go.set

go.set(url, property, value)

Parameters

url

string | hash | url url of the game object or component having the property

property

string | hash id of the property to set

value

any the value to set

url

string | hash | url url of the game object or component having the property

property

string | hash id of the property to set

value

any the value to set

Examples

Set a property "speed" of a script "player", the property must be declared in the player-script:

go.property("speed", 50)

Then in the calling script (assumed to belong to the same game object, but does not have to):

go.set("#player", "speed", 100)

go.set_position

go.set_position(position, [id])

The position is relative to the parent (if any). The global world position cannot be manually set.

Parameters

position

vector3 position to set

[id]

string | hash | url optional id of the game object instance to set the position for, by default the instance of the calling script

position

vector3 position to set

[id]

string | hash | url optional id of the game object instance to set the position for, by default the instance of the calling script

Examples

Set the position of the game object instance the script is attached to:

local p = ...
go.set_position(p)

Set the position of another game object instance with id "x":

local p = ...
go.set_position(p, "x")

go.set_rotation

go.set_rotation(rotation, [id])

The rotation is relative to the parent (if any). The global world rotation cannot be manually set.

Parameters

rotation

quaternion rotation to set

[id]

string | hash | url optional id of the game object instance to get the rotation for, by default the instance of the calling script

rotation

quaternion rotation to set

[id]

string | hash | url optional id of the game object instance to get the rotation for, by default the instance of the calling script

Examples

Set the rotation of the game object instance the script is attached to:

local r = ...
go.set_rotation(r)

Set the rotation of another game object instance with id "x":

local r = ...
go.set_rotation(r, "x")

go.set_scale

go.set_scale(scale, [id])

The scale factor is relative to the parent (if any). The global world scale factor cannot be manually set.

Physics are currently not affected when setting scale from this function.

Parameters

scale

number | vector3 vector or uniform scale factor, must be greater than 0

[id]

string | hash | url optional id of the game object instance to get the scale for, by default the instance of the calling script

scale

number | vector3 vector or uniform scale factor, must be greater than 0

[id]

string | hash | url optional id of the game object instance to get the scale for, by default the instance of the calling script

Examples

Set the scale of the game object instance the script is attached to:

local s = vmath.vector3(2.0, 1.0, 1.0)
go.set_scale(s)

Set the scale of another game object instance with id "x":

local s = 1.2
go.set_scale(s, "x")

init

init(self)

This is a callback-function, which is called by the engine when a script component is initialized. It can be used to set the initial state of the script.

Parameters

self

object reference to the script state to be used for storing data

self

object reference to the script state to be used for storing data

Examples

function init(self)
    -- set up useful data
    self.my_value = 1
end

on_input

on_input(self, action_id, action)

This is a callback-function, which is called by the engine when user input is sent to the game object instance of the script. It can be used to take action on the input, e.g. move the instance according to the input.

For an instance to obtain user input, it must first acquire input focus through the message acquire_input_focus.

Any instance that has obtained input will be put on top of an input stack. Input is sent to all listeners on the stack until the end of stack is reached, or a listener returns true to signal that it wants input to be consumed.

See the documentation of acquire_input_focus for more information.

The action parameter is a table containing data about the input mapped to the action_id. For mapped actions it specifies the value of the input and if it was just pressed or released. Actions are mapped to input in an input_binding-file.

Mouse movement is specifically handled and uses nil as its action_id. The action only contains positional parameters in this case, such as x and y of the pointer.

Here is a brief description of the available table fields:

Field Description
value The amount of input given by the user. This is usually 1 for buttons and 0-1 for analogue inputs. This is not present for mouse movement.
pressed If the input was pressed this frame, 0 for false and 1 for true. This is not present for mouse movement.
released If the input was released this frame, 0 for false and 1 for true. This is not present for mouse movement.
repeated If the input was repeated this frame, 0 for false and 1 for true. This is similar to how a key on a keyboard is repeated when you hold it down. This is not present for mouse movement.
x The x value of a pointer device, if present.
y The y value of a pointer device, if present.
screen_x The screen space x value of a pointer device, if present.
screen_y The screen space y value of a pointer device, if present.
dx The change in x value of a pointer device, if present.
dy The change in y value of a pointer device, if present.
screen_dx The change in screen space x value of a pointer device, if present.
screen_dy The change in screen space y value of a pointer device, if present.
gamepad The index of the gamepad device that provided the input.
touch List of touch input, one element per finger, if present. See table below about touch input

Touch input table:

Field Description
id A number identifying the touch input during its duration.
pressed True if the finger was pressed this frame.
released True if the finger was released this frame.
tap_count Number of taps, one for single, two for double-tap, etc
x The x touch location.
y The y touch location.
dx The change in x value.
dy The change in y value.
acc_x Accelerometer x value (if present).
acc_y Accelerometer y value (if present).
acc_z Accelerometer z value (if present).

Parameters

self

object reference to the script state to be used for storing data

action_id

hash id of the received input action, as mapped in the input_binding-file

action

table a table containing the input data, see above for a description

self

object reference to the script state to be used for storing data

action_id

hash id of the received input action, as mapped in the input_binding-file

action

table a table containing the input data, see above for a description

Returns

[consume]

boolean optional boolean to signal if the input should be consumed (not passed on to others) or not, default is false

[consume]

boolean optional boolean to signal if the input should be consumed (not passed on to others) or not, default is false

Examples

This example demonstrates how a game object instance can be moved as a response to user input.

function init(self)
    -- acquire input focus
    msg.post(".", "acquire_input_focus")
    -- maximum speed the instance can be moved
    self.max_speed = 2
    -- velocity of the instance, initially zero
    self.velocity = vmath.vector3()
end

function update(self, dt)
    -- move the instance
    go.set_position(go.get_position() + dt * self.velocity)
end

function on_input(self, action_id, action)
    -- check for movement input
    if action_id == hash("right") then
        if action.released then -- reset velocity if input was released
            self.velocity = vmath.vector3()
        else -- update velocity
            self.velocity = vmath.vector3(action.value * self.max_speed, 0, 0)
        end
    end
end

on_message

on_message(self, message_id, message, sender)

This is a callback-function, which is called by the engine whenever a message has been sent to the script component. It can be used to take action on the message, e.g. send a response back to the sender of the message.

The message parameter is a table containing the message data. If the message is sent from the engine, the documentation of the message specifies which data is supplied.

Parameters

self

object reference to the script state to be used for storing data

message_id

hash id of the received message

message

table a table containing the message data

sender

url address of the sender

self

object reference to the script state to be used for storing data

message_id

hash id of the received message

message

table a table containing the message data

sender

url address of the sender

Examples

This example demonstrates how a game object instance, called "a", can communicate with another instance, called "b". It is assumed that both script components of the instances has id "script".

Script of instance "a":

function init(self)
    -- let b know about some important data
    msg.post("b#script", "my_data", {important_value = 1})
end

Script of instance "b":

function init(self)
    -- store the url of instance "a" for later use, by specifying nil as socket we
    -- automatically use our own socket
    self.a_url = msg.url(nil, go.get_id("a"), "script")
end

function on_message(self, message_id, message, sender)
    -- check message and sender
    if message_id == hash("my_data") and sender == self.a_url then
        -- use the data in some way
        self.important_value = message.important_value
    end
end

on_reload

on_reload(self)

This is a callback-function, which is called by the engine when the script component is reloaded, e.g. from the editor. It can be used for live development, e.g. to tweak constants or set up the state properly for the instance.

Parameters

self

object reference to the script state to be used for storing data

self

object reference to the script state to be used for storing data

Examples

This example demonstrates how to tweak the speed of a game object instance that is moved on user input.

function init(self)
    -- acquire input focus
    msg.post(".", "acquire_input_focus")
    -- maximum speed the instance can be moved, this value is tweaked in the on_reload function below
    self.max_speed = 2
    -- velocity of the instance, initially zero
    self.velocity = vmath.vector3()
end

function update(self, dt)
    -- move the instance
    go.set_position(go.get_position() + dt * self.velocity)
end

function on_input(self, action_id, action)
    -- check for movement input
    if action_id == hash("right") then
        if action.released then -- reset velocity if input was released
            self.velocity = vmath.vector3()
        else -- update velocity
            self.velocity = vmath.vector3(action.value * self.max_speed, 0, 0)
        end
    end
end

function on_reload(self)
    -- edit this value and reload the script component
    self.max_speed = 100
end

update

update(self, dt)

This is a callback-function, which is called by the engine every frame to update the state of a script component. It can be used to perform any kind of game related tasks, e.g. moving the game object instance.

Parameters

self

object reference to the script state to be used for storing data

dt

number the time-step of the frame update

self

object reference to the script state to be used for storing data

dt

number the time-step of the frame update

Examples

This example demonstrates how to move a game object instance through the script component:

function init(self)
    -- set initial velocity to be 1 along world x-axis
    self.my_velocity = vmath.vector3(1, 0, 0)
end

function update(self, dt)
    -- move the game object instance
    go.set_position(go.get_position() + dt * self.my_velocity)
end

Messages

acquire_input_focus

"acquire_input_focus"

Post this message to a game object instance to make that instance acquire the user input focus.

User input is distributed by the engine to every instance that has requested it. The last instance to request focus will receive it first. This means that the scripts in the instance will have first-hand-chance at reacting on user input, possibly consuming it (by returning true from on_input) so that no other instances can react on it. The most common case is for a script to send this message to itself when it needs to respond to user input.

A script belonging to an instance which has the user input focus will receive the input actions in its on_input callback function. See on_input for more information on how user input can be handled.

Examples

This example demonstrates how to acquire and act on user input.

function init(self)
    -- acquire input focus as soon as the instance has been initialized
    msg.post(".", "acquire_input_focus")
end

function on_input(self, action_id, action)
    -- check which input we received
    if action_id == hash("my_action") then
        -- act on the input
        self.my_action_amount = action.value
    end
end

disable

"disable"

This message disables the receiving component. All components are enabled by default, which means they will receive input, updates and be a part of the simulation. A component is disabled when it receives the disable message.

Components that currently supports this message are:

  • Collection Proxy
  • Collision Object
  • Gui
  • Label
  • Spine Model
  • Sprite
  • Tile Grid
  • Model

Examples

Disable the component "my_component":

msg.post("#my_component", "disable")

enable

"enable"

This message enables the receiving component. All components are enabled by default, which means they will receive input, updates and be a part of the simulation. A component is disabled when it receives the disable message.

Components that currently supports this message are:

  • Collection Proxy
  • Collision Object
  • Gui
  • Label
  • Spine Model
  • Sprite
  • Tile Grid
  • Model

Examples

Enable the component "my_component":

msg.post("#my_component", "enable")

release_input_focus

"release_input_focus"

Post this message to an instance to make that instance release the user input focus. See acquire_input_focus for more information on how the user input handling works.

Examples

How to make a game object stop receiving input:

msg.post(".", "release_input_focus")

set_parent

"set_parent", { parent_id=…, keep_world_transform=… }

When this message is sent to an instance, it sets the parent of that instance. This means that the instance will exist in the geometrical space of its parent, like a basic transformation hierarchy or scene graph. If no parent is specified, the instance will be detached from any parent and exist in world space. A script can send this message to itself to set the parent of its instance.

Fields

parent_id

hash the id of the new parent

keep_world_transform

number if the world transform of the instance should be preserved when changing spaces, 0 for false and 1 for true. The default value is 1.

parent_id

hash the id of the new parent

keep_world_transform

number if the world transform of the instance should be preserved when changing spaces, 0 for false and 1 for true. The default value is 1.

Examples

Attach myself to another instance "my_parent":

msg.post(".", "set_parent", {parent_id = go.get_id("my_parent")})

Attach an instance "my_instance" to another instance "my_parent":

msg.post("my_instance", "set_parent", {parent_id = go.get_id("my_parent")})

Detach an instance "my_instance" from its parent (if any):

msg.post("my_instance", "set_parent")

Constants

go.EASING_INBACK

go.EASING_INBOUNCE

go.EASING_INCIRC

go.EASING_INCUBIC

go.EASING_INELASTIC

go.EASING_INEXPO

go.EASING_INOUTBACK

go.EASING_INOUTBOUNCE

go.EASING_INOUTCIRC

go.EASING_INOUTCUBIC

go.EASING_INOUTELASTIC

go.EASING_INOUTEXPO

go.EASING_INOUTQUAD

go.EASING_INOUTQUART

go.EASING_INOUTQUINT

go.EASING_INOUTSINE

go.EASING_INQUAD

go.EASING_INQUART

go.EASING_INQUINT

go.EASING_INSINE

go.EASING_LINEAR

go.EASING_OUTBACK

go.EASING_OUTBOUNCE

go.EASING_OUTCIRC

go.EASING_OUTCUBIC

go.EASING_OUTELASTIC

go.EASING_OUTEXPO

go.EASING_OUTINBACK

go.EASING_OUTINBOUNCE

go.EASING_OUTINCIRC

go.EASING_OUTINCUBIC

go.EASING_OUTINELASTIC

go.EASING_OUTINEXPO

go.EASING_OUTINQUAD

go.EASING_OUTINQUART

go.EASING_OUTINQUINT

go.EASING_OUTINSINE

go.EASING_OUTQUAD

go.EASING_OUTQUART

go.EASING_OUTQUINT

go.EASING_OUTSINE

go.PLAYBACK_LOOP_BACKWARD

go.PLAYBACK_LOOP_FORWARD

go.PLAYBACK_LOOP_PINGPONG

go.PLAYBACK_NONE

go.PLAYBACK_ONCE_BACKWARD

go.PLAYBACK_ONCE_FORWARD

go.PLAYBACK_ONCE_PINGPONG

Properties

euler

The rotation of the game object expressed in Euler angles. Euler angles are specified in degrees. The type of the property is vector3.

Examples

How to set a game object's rotation with euler angles, either as a vector3 or selecting a specific dimension:

function init(self)
  -- set "player" euler z rotation component to 45 degrees around z.
  local rotz = 45
  go.set("player", "euler.z", rotz)
  local rot = go.get("player", "euler")
  -- do something useful
  assert(rot.z == rotz)
end

position

The position of the game object. The type of the property is vector3.

Examples

How to query a game object's position, either as a vector3 or selecting a specific dimension:

function init(self)
  -- get position from "player"
  local pos = go.get("player", "position")
  local posx = go.get("player", "position.x")
  -- do something useful
  assert(pos.x == posx)
end

rotation

The rotation of the game object. The type of the property is quaternion.

Examples

How to set a game object's rotation:

function init(self)
  -- set "player" rotation to 45 degrees around z.
  local rotz = vmath.quat_rotation_z(3.141592 / 4)
  go.set("player", "rotation", rotz)
end

scale

The uniform scale of the game object. The type of the property is number.

Examples

How to scale a game object:

function init(self)
  -- Double the scaling on "player"
  local scale = go.get("player", "scale")
  go.set("player", "scale", scale * 2)
end

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