Introduction
Updated 198 Days AgoPublic

Lua (LUI) Getting Started

Lua is a fairly simple language to learn, it's syntax is similar to python. However, the Lua implementation in Call of Duty Black Ops 3 (HavokScript) has slight differences which you'll need to be aware of. This tutorial will NOT go over how to script in Lua, you must learn that on your own! However, this will outline some of the key differences that you will need to follow.

Requiring another script

In standard Lua, you can require another script using:

-- Use the file in the folder 'a' named 'b.lua'
require("a/b.lua")

In BO3, you can still do this, however, the syntax is different:

-- Use the file in the folder 'a' named 'b.lua'
require("a.b")

Basically, the paths are now '.' and you remove the trailing '.lua'. This functions the same as standard lua.

Function scopes

Normally it's ok to declare global functions and variables in standard Lua without an issue. However, in BO3 unless otherwise stated. All variables and functions should be local:

local function Hello()
    print("Hello world!")
end

local function Test()
    local Wins = ""
end

Otherwise, you may hit a random out of memory issue...

Catching call exceptions

In BO3 Lua, you can catch a function for errors, but you must wrap the call...

function test()
    <something that errors>
end

if pcall(test) then
    success
else
    failed
end

Wrapping the call in a pcall will prevent errors from halting the game.

LUI Specific Information

Below is a list of LUI specific data for use with the other tutorials, you should be familiar with these concepts:

  • Stock menu size: 1280x960 (Up-scaled and Down-scaled as needed).
  • LUI is the root namespace of elements.
    • UIElement is the root of all elements and can house other controls.
    • UIText element's font size is determined by the height of the control alone.
    • UIImage element's image will stretch to fit the control size.
  • All controls support AnchorLeft, AnchorRight, AnchorTop, and AnchorBottom for responsive layout design.
  • A Widget is a collection of the base elements into a custom control. Widgets are not stock elements.
  • To include a custom menu, you use #precache("lui_menu", "<name of lua file>") in script files.
  • To use a menu property name, you must use #precache("lui_menu_data", "property name") in script files.
  • To use a LUI event name, you must use #precache("eventstring", "event name") in script files.
  • To include a file, you use rawfile,<lua file path>.lua the same as any other file.
  • With linker, you can include pre-compiled Lua files with *.luac extensions.
  • Only syntax errors are caught at compile-time, if an error occurs in-game, this will break all existing menus.
  • For custom maps, your hud is going to override T7Hud_zm_factory.
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