Unreal

For all Unreal Engine based games, you can use the Unreal namespace to access any Unreal objects the engine exports and take your scripts to a next level.

UObject

UObject type represents any Unreal Engine object. There are three functions that return Unreal Object instances.

-- Gets the global UEngine instance.
--
UObject  Unreal.GetEngine()

-- Gets the Unreal Object and of any entity from the entity list.
--
UObject  Unreal.From(Entity entity)

-- Gets the default instance of a class type.
--
UObject? Unreal.DefaultInstance(UClass|string class)

-- Gets and sets the value of a field.
--
any      UObject:__index(string|int k)
void     UObject:__newindex(string|int k, any v)

You can transparently read (and write for numeric/vector fields) any public field by their name, convert the objects into string, and compare them.

Example/index.lua

local world = Unreal.GetEngine().GameViewport.World
local levels = world.Levels
local persistentLevel = world.PersistentLevel
for i=1,#levels do
    local level = levels[i]
   -- Prints 'Level #1 = 'Level @ 000001ED264FE200' (Persistent)'
    print(string.format("Level #%d = '%s' %s", i, level, level == persistentLevel ? "(Persistent)" : ""))
end

Note that FVector and FRotator instances will be automatically converted to vec3 and will be transformed into our coordinate system.

UClass

UClass type represents the metadata for all UObject types. You can get the UClass object either by name or from an already existing UObject instance.

-- Gets a class instance by name.
--
UClass?           Unreal.StaticClass(string name)

-- Gets the class of an object.
--
UClass?           Unreal.GetClass(UObject object)

-- Gets an iterator for all classes, if an UClass is given, filters to classes inherting from it.
--
Iterable<UClass>  Unreal.Classes(UClass? super)

-- Gets an array containing all super classes in order.
--
UClass[]          Unreal.Hierarchy(UClass class)

-- Returns the number of fields.
--
uint              UClass:__len()

-- Gets the Nth field's name.
--
string?           UClass:__index(uint i)

The UClass type can be enumerated like an array to get information about the fields.

Example/index.lua

local function printFields(object)
    local class = Unreal.GetClass(object)
    local fieldCount = #class
    for i=1,fieldCount do
        if i == 11 then
            print(string.format("... (%d more)", fieldCount - 10))
            break
        else
            local fieldName = class[i]
            print(string.format("  .%s = %s", fieldName, object[fieldName]))
        end
    end
end

printFields(Unreal.GetEngine())
-- Prints:
--  .TinyFont = Font @ 000001ED39495000
--  .TinyFontName = SoftObjectPath @ 000001ED23035BF8
--  .SmallFont = Font @ 000001ED39495200
--  .SmallFontName = SoftObjectPath @ 000001ED23035C18
--  .MediumFont = Font @ 000001ED39495200
--  .MediumFontName = SoftObjectPath @ 000001ED23035C38
--  .LargeFont = Font @ 000001ED39495200
--  .LargeFontName = SoftObjectPath @ 000001ED23035C58
--  .SubtitleFont = Font @ 000001ED39495200
--  .SubtitleFontName = SoftObjectPath @ 000001ED23035C78
--... (217 more)

You can also check if an UObject instance is of the given class type or not by using the IsA function.

-- Returns true if object isn instance of the given class.
--
bool     Unreal.IsA(UObject object, UClass class)

Example/index.lua

local worldClass = Unreal.StaticClass("World")
local world =      Unreal.GetEngine().GameViewport.World
print(Unreal.IsA(world, worldClass)) -- Prints 'true'