Lua is a complete, full-featured language. It makes the Dialogue System extremely powerful. Using Lua, you can add very sophisticated behavior to your games. But even using only two operations – test for equality ("==") and assignment ("=") – you can make very complex, interactive dialogue without having to do anything else in Lua.

If you don't want to touch Lua code at all, you can still use the point-and-click Lua Wizards.

Lua Syntax Gotchas

If you're familiar with C# or UnityScript, Lua has a few syntax differences to be aware of:

Operator	C#/UnityScript	Lua	Lua Example
Not equal	`!=`	`~=`	`Quest["Kill_5_Rats"].State ~= "success"`
Logical AND	`&&`	`and`	`Variable["HasCoke"] and Variable["HasMentos"]`
Logical OR	\|\|	`or`	`(Actor["Player"].Age > 21) or Item["Beverage"].IsNonalcoholic`
String concatenation	`+`	`..`	`Actor["Player"].FullTitle = "Dread Lord " .. Actor["Player"].Name .. " of Skull Island"`
`if`	`if(x==y)`	`if (x==y)` (blank space req'd)	`if (x == y) then foo() end`

Special Exception: LuaInterpreter "and not"

The default Lua implementation that ships with the Dialogue System is LuaInterpreter. This is a fast, lightweight C# implementation of Lua. However, it does not parse one valid Lua syntax: X and not Y, as shown below:

foo and not bar

You can usually work around this limit by modifying your syntax slightly. If you must use and not, you can switch to NLua (see Using NLua).

Checking Values

Here are some examples that you could use in a dialogue entry's Conditions field. The entry will only be considered if the condition is true.

Check Variable

Check if a Boolean variable has been set true (note the use of double equals "==" to test equality):

Variable["flippedSwitch"] == true

Check Quest State

Check if a quest is in a specific state:

CurrentQuestState("Kill 5 Rats") == "success"

Check Actor and Item Fields

Check if the player is at least 21 and has at least one beer:

(Actor["Player"].Age >= 21) and (Item["Beer"].Count > 0)

Conditions in Triggers

You can also use conditions like the examples above in a trigger's Trigger Conditions. In triggers, you can also add quest conditions, which are more convenient for checking quest states than writing Lua conditions.

Assigning Values

Here are some examples of setting values. You could use them in a dialogue entry's Script field or in the Lua On Dialogue Event component.

Set Variable

Set a variable (note the use of single equals "=" for assignment):

Variable["spokeToKing"] = true;
Variable["Gold"] = Variable["Gold"] + 50

Set Quest State

Set a quest to a specific state:

SetQuestState("Kill 5 Rats", "active")

Combining Strings

Combining two strings (using Lua's '..' notation):

Actor["Player"].FullTitle = "Dread Lord " .. Actor["Player"].Name .. " of Skull Island"

Special Functions

The Dialogue System exposes several useful functions, including:

Chat Mapper Functions - Functions to manage status between two assets (e.g., actors) and relationships between actors.
Other Useful Functions

Networking Functions

The Dialogue System includes Lua functions that synchronize variables and quest states to all clients using Unity Networking's High Level API (UNET HLAPI). For instructions, see: