System API documentation

Version: stable

Functions

sys.save()

sys.save(filename,table)

The table can later be loaded by sys.load. Use sys.get_save_file to obtain a valid location for the file. Internally, this function uses a workspace buffer sized output file sized 512kb. This size reflects the output file size which must not exceed this limit. Additionally, the total number of rows that any one table may contain is limited to 65536 (i.e. a 16 bit range). When tables are used to represent arrays, the values of keys are permitted to fall within a 32 bit range, supporting sparse arrays, however the limit on the total number of rows remains in effect.

PARAMETERS

RETURNS

EXAMPLES

local my_table = {}
table.insert(my_table, "my_value")
local my_file_path = sys.get_save_file("my_game", "my_file")
if not sys.save(my_file_path, my_table) then
  -- Alert user that the data could not be saved
end

sys.load()

sys.load(filename)

If the file exists, it must have been created by sys.save to be loaded.

PARAMETERS

RETURNS

EXAMPLES

local my_file_path = sys.get_save_file("my_game", "my_file")
local my_table = sys.load(my_file_path)
if not next(my_table) then
  -- empty table
end

sys.exists()

sys.exists(path)

Check if a path exists Good for checking if a file exists before loading a large file

PARAMETERS

RETURNS

EXAMPLES

if not sys.exists(path) then
    return nil
end
return sys.load(path) -- returns {} if it failed

sys.get_host_path()

sys.get_host_path(filename)

Create a path to the host device for unit testing Useful for saving logs etc during development

PARAMETERS

RETURNS

EXAMPLES

local host_path = sys.get_host_path("logs/test.txt")
sys.save(host_path, mytable)

local host_path = sys.get_host_path("logs/test.txt")
local table = sys.load(host_path)

sys.get_save_file()

sys.get_save_file(application_id,file_name)

The save-file path is operating system specific and is typically located under the user's home directory.

PARAMETERS

RETURNS

EXAMPLES

local my_file_path = sys.get_save_file("my_game", "my_file")
print(my_file_path) --> /Users/my_users/Library/Application Support/my_game/my_file

sys.get_application_path()

sys.get_application_path()

The path from which the application is run.

PARAMETERS

None

RETURNS

EXAMPLES

-- macOS: /Applications/my_game.app
local application_path = sys.get_application_path()
print(application_path) --> /Applications/my_game.app

-- Windows: C:\Program Files\my_game\my_game.exe
print(application_path) --> C:\Program Files\my_game

-- Linux: /home/foobar/my_game/my_game
print(application_path) --> /home/foobar/my_game

-- Android package name: com.foobar.my_game
print(application_path) --> /data/user/0/com.foobar.my_game

-- iOS: my_game.app
print(application_path) --> /var/containers/Bundle/Applications/123456AB-78CD-90DE-12345678ABCD/my_game.app

-- HTML5: http://www.foobar.com/my_game/
print(application_path) --> http://www.foobar.com/my_game

sys.get_config_string()

sys.get_config_string(key,[default_value])

Get string config value from the game.project configuration file with optional default value

PARAMETERS

RETURNS

EXAMPLES

local text = sys.get_config_string("my_game.text", "default text"))

$ dmengine --config=bootstrap.main_collection=/mytest.collectionc --config=mygame.testmode=1

local testmode = sys.get_config_int("mygame.testmode")

sys.get_config_int()

sys.get_config_int(key,[default_value])

Get integer config value from the game.project configuration file with optional default value

PARAMETERS

RETURNS

EXAMPLES

local speed = sys.get_config_int("my_game.speed", 20) -- with default value

local testmode = sys.get_config_int("my_game.testmode") -- without default value
if testmode ~= nil then
    -- do stuff
end

sys.get_config_number()

sys.get_config_number(key,[default_value])

Get number config value from the game.project configuration file with optional default value

PARAMETERS

RETURNS

EXAMPLES

local speed = sys.get_config_number("my_game.speed", 20.0)

sys.open_url()

sys.open_url(url,[attributes])

Open URL in default application, typically a browser

PARAMETERS

RETURNS

EXAMPLES

local success = sys.open_url("http://www.defold.com", {target = "_blank"})
if not success then
  -- could not open the url...
end

sys.load_resource()

sys.load_resource(filename)

Loads a custom resource. Specify the full filename of the resource that you want to load. When loaded, the file data is returned as a string. If loading fails, the function returns nil plus the error message. In order for the engine to include custom resources in the build process, you need to specify them in the "custom_resources" key in your "game.project" settings file. You can specify single resource files or directories. If a directory is included in the resource list, all files and directories in that directory is recursively included: For example "main/data/,assets/level_data.json".

PARAMETERS

RETURNS

EXAMPLES

-- Load level data into a string
local data, error = sys.load_resource("/assets/level_data.json")
-- Decode json string to a Lua table
if data then
  local data_table = json.decode(data)
  pprint(data_table)
else
  print(error)
end

sys.get_sys_info()

sys.get_sys_info([options])

Returns a table with system information.

PARAMETERS

RETURNS

EXAMPLES

local info = sys.get_sys_info()
if info.system_name == "HTML5" then
  -- We are running in a browser.
end

sys.get_engine_info()

sys.get_engine_info()

Returns a table with engine information.

PARAMETERS

None

RETURNS

EXAMPLES

-- Update version text label so our testers know what version we're running
local engine_info = sys.get_engine_info()
local version_str = "Defold " .. engine_info.version .. "\n" .. engine_info.version_sha1
gui.set_text(gui.get_node("version"), version_str)

sys.get_application_info()

sys.get_application_info(app_string)

Returns a table with application information for the requested app. On iOS, the app_string is an url scheme for the app that is queried. Your game needs to list the schemes that are queried in an LSApplicationQueriesSchemes array in a custom "Info.plist". On Android, the app_string is the package identifier for the app.

PARAMETERS

RETURNS

EXAMPLES

sysinfo = sys.get_sys_info()
twitter = {}

if sysinfo.system_name == "Android" then
  twitter = sys.get_application_info("com.twitter.android")
elseif sysinfo.system_name == "iPhone OS" then
  twitter = sys.get_application_info("twitter:")
end

if twitter.installed then
  -- twitter is installed!
end

...
<key>LSApplicationQueriesSchemes</key>
 <array>
   <string>twitter</string>
 </array>
...

sys.get_ifaddrs()

sys.get_ifaddrs()

Returns an array of tables with information on network interfaces.

PARAMETERS

None

RETURNS

EXAMPLES

ifaddrs = sys.get_ifaddrs()
for _,interface in ipairs(ifaddrs) do
  if interface.name == "en0" then
    local ip = interface.address
  end
end

sys.set_error_handler()

sys.set_error_handler(error_handler)

Set the Lua error handler function. The error handler is a function which is called whenever a lua runtime error occurs.

PARAMETERS

EXAMPLES

local function my_error_handler(source, message, traceback)
  print(source)    --> lua
  print(message)   --> main/my.script:10: attempt to perform arithmetic on a string value
  print(traceback) --> stack traceback:
                   -->         main/test.script:10: in function 'boom'
                   -->         main/test.script:15: in function <main/my.script:13>
end

local function boom()
  return 10 + "string"
end

function init(self)
  sys.set_error_handler(my_error_handler)
  boom()
end

sys.set_connectivity_host()

sys.set_connectivity_host(host)

Sets the host that is used to check for network connectivity against.

PARAMETERS

EXAMPLES

sys.set_connectivity_host("www.google.com")

sys.get_connectivity()

sys.get_connectivity()

Returns the current network connectivity status on mobile platforms. On desktop, this function always return sys.NETWORK_CONNECTED.

PARAMETERS

None

RETURNS

EXAMPLES

if (sys.NETWORK_CONNECTED_CELLULAR == sys.get_connectivity()) then
  print("Connected via cellular, avoid downloading big files!")
end

sys.exit()

sys.exit(code)

Terminates the game application and reports the specified code to the OS.

PARAMETERS

EXAMPLES

function on_message(self, message_id, message, sender)
    if message_id == hash("quit") then
        sys.exit(0)
    end
end

sys.reboot()

sys.reboot(arg1,arg2,arg3,arg4,arg5,arg6)

Reboots the game engine with a specified set of arguments. Arguments will be translated into command line arguments. Calling reboot function is equivalent to starting the engine with the same arguments. On startup the engine reads configuration from "game.project" in the project root.

PARAMETERS

EXAMPLES

local arg1 = '--config=bootstrap.main_collection=/my.collectionc'
local arg2 = 'build/game.projectc'
sys.reboot(arg1, arg2)

sys.set_vsync_swap_interval()

sys.set_vsync_swap_interval(swap_interval)

Set the vsync swap interval. The interval with which to swap the front and back buffers in sync with vertical blanks (v-blank), the hardware event where the screen image is updated with data from the front buffer. A value of 1 swaps the buffers at every v-blank, a value of 2 swaps the buffers every other v-blank and so on. A value of 0 disables waiting for v-blank before swapping the buffers. Default value is 1. When setting the swap interval to 0 and having vsync disabled in "game.project", the engine will try to respect the set frame cap value from "game.project" in software instead. This setting may be overridden by driver settings.

PARAMETERS

EXAMPLES

sys.set_vsync_swap_interval(1)

sys.set_update_frequency()

sys.set_update_frequency(frequency)

Set game update-frequency (frame cap). This option is equivalent to display.update_frequency in the "game.project" settings but set in run-time. If Vsync checked in "game.project", the rate will be clamped to a swap interval that matches any detected main monitor refresh rate. If Vsync is unchecked the engine will try to respect the rate in software using timers. There is no guarantee that the frame cap will be achieved depending on platform specifics and hardware settings.

PARAMETERS

EXAMPLES

sys.set_update_frequency(60)

sys.serialize()

sys.serialize(table)

The buffer can later deserialized by sys.deserialize. This method has all the same limitations as sys.save.

PARAMETERS

RETURNS

EXAMPLES

local my_table = {}
table.insert(my_table, "my_value")
local buffer = sys.serialize(my_table)

sys.deserialize()

sys.deserialize(buffer)

deserializes buffer into a lua table

PARAMETERS

RETURNS

EXAMPLES

local buffer = sys.serialize(my_table)
local table = sys.deserialize(buffer)

Constants

sys.NETWORK_DISCONNECTED

no network connection found

sys.NETWORK_CONNECTED_CELLULAR

network connected through mobile cellular

sys.NETWORK_CONNECTED

network connected through other, non cellular, connection

Messages

exit

Terminates the game application and reports the specified code to the OS. This message can only be sent to the designated @system socket.

EXAMPLES

function on_message(self, message_id, message, sender)
    if message_id == hash("quit") then
        msg.post("@system:", "exit", {code = 0})
    end
end

toggle_profile

Toggles the on-screen profiler. The profiler is a real-time tool that shows the numbers of milliseconds spent in each scope per frame as well as counters. The profiler is very useful for tracking down performance and resource problems. In addition to the on-screen profiler, Defold includes a web-based profiler that allows you to sample a series of data points and then analyze them in detail. The web profiler is available at http://<device IP>:8002 where is the IP address of the device you are running your game on. This message can only be sent to the designated @system socket.

EXAMPLES

msg.post("@system:", "toggle_profile")

toggle_physics_debug

Toggles the on-screen physics visual debugging mode which is very useful for tracking down issues related to physics. This mode visualizes all collision object shapes and normals at detected contact points. Toggling this mode on is equal to setting physics.debug in the "game.project" settings, but set in run-time. This message can only be sent to the designated @system socket.

EXAMPLES

msg.post("@system:", "toggle_physics_debug")

start_record

Starts video recording of the game frame-buffer to file. Current video format is the open vp8 codec in the ivf container. It's possible to upload this format directly to YouTube. The VLC video player has native support but with the known issue that not the entire file is played back. It's probably an issue with VLC. The Miro Video Converter has support for vp8/ivf. Video recording is only supported on desktop platforms. Audio is currently not supported Window width and height must be a multiple of 8 to be able to record video. This message can only be sent to the designated @system socket.

EXAMPLES

msg.post("@system:", "start_record", { file_name = "test_rec.ivf" } )

msg.post("@system:", "start_record", { file_name = "test_rec.ivf", frame_period = 1, fps = 60 } )

stop_record

Stops the currently active video recording. Video recording is only supported on desktop platforms. This message can only be sent to the designated @system socket.

EXAMPLES

msg.post("@system:", "stop_record")

reboot

Reboots the game engine with a specified set of arguments. Arguments will be translated into command line arguments. Sending the reboot command is equivalent to starting the engine with the same arguments. On startup the engine reads configuration from "game.project" in the project root. This message can only be sent to the designated @system socket.

EXAMPLES

local arg1 = '--config=bootstrap.main_collection=/my.collectionc'
local arg2 = 'build/game.projectc'
msg.post("@system:", "reboot", {arg1 = arg1, arg2 = arg2})

set_vsync

Set the vsync swap interval. The interval with which to swap the front and back buffers in sync with vertical blanks (v-blank), the hardware event where the screen image is updated with data from the front buffer. A value of 1 swaps the buffers at every v-blank, a value of 2 swaps the buffers every other v-blank and so on. A value of 0 disables waiting for v-blank before swapping the buffers. Default value is 1. When setting the swap interval to 0 and having vsync disabled in "game.project", the engine will try to respect the set frame cap value from "game.project" in software instead. This setting may be overridden by driver settings. This message can only be sent to the designated @system socket.

EXAMPLES

msg.post("@system:", "set_vsync", { swap_interval = 1 } )

set_update_frequency

Set game update-frequency (frame cap). This option is equivalent to display.update_frequency in the "game.project" settings but set in run-time. If Vsync checked in "game.project", the rate will be clamped to a swap interval that matches any detected main monitor refresh rate. If Vsync is unchecked the engine will try to respect the rate in software using timers. There is no guarantee that the frame cap will be achieved depending on platform specifics and hardware settings. This message can only be sent to the designated @system socket.

EXAMPLES

msg.post("@system:", "set_update_frequency", { frequency = 60 } )