ZScript data types

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Note: This feature is for ZScript only.

ZScript introduces a variety of new variables usable within actors, including structs. These must be defined either inside regular/anonymous functions, or outside the 'Default {}' block, which is used for an Actor class's internal properties only.



See this page for more information on what the types are and their aliases. They are defined as shown below, NOT like in C++ (i.e. no unsigned word or underscore).

Arithmetic data types can be utilized with arithmetic operators.

  • bool
  • double
Float-point numbers with high precision. Support the following:
  • ~== — approximately equal check (see here).
  • double.NaN — Short for "not a number", used to invalidate a double. Checking for a NaN is done by seeing if a variable is NOT equal to itself, e.g. if (myDouble != myDouble).
  • int
Integer number
  • uint
Unsigned integer number (cannot be negative).


  • Vector2 ToVector(double number)
Converts a number to a Vector2 that contains (cos(number), sin(number)).


  • Vector2
2-component vector. Has x and y components.
  • Vector3
3-component vector. Has x, y and z components.
  • Vector4
4-component vector. Has x, y, z and w components.


Note: Vectors currently cannot be used in dynamic arrays.

  • double Length()
Returns the length of the vector as a double. Effectively performs sqrt(x*x + y*y) for Vector2, sqrt(x*x + y*y + z*z) for Vector3, sqrt(w*w + x*x + y*y + z*z) for Vector4.
  • double LengthSquared()
Same as Length() but does not square root it. More efficient than using a sqrt.
  • Vector2 Unit()
Vector3 Unit()
Vector4 Unit()
Returns a vector with all members multiplied by 1 / Length(), giving a vector with a length of 1.
If the length of the base vector is 0, this will return a Vector# where every value is NaN.
  • Vector3 PlusZ(double offset)
Returns a Vector3 with the z offset by the given amount. Only available for Vector3.

See ZScript special words for more functionality related to vectors.


Note: Quats currently cannot be used in dynamic arrays.

  • Quat
See Quaternion.


  • String
Case-sensitive text strings. Strings should be enclosed with double quotation marks: "MyString".
Strings support relational operators. Note that ~== can be used to perform a case-insensitive string comparison.
Support string formatting (see the String page for more information).

Strings can be directly converted to names and vice versa, for example:

String foo = "MyString";
name bar = foo; //bar = 'mystring'


  • Name
Case-insensitive text strings. Should be enclosed with single quotation marks: 'myname'.
Strings support relational operators.
String formatting is not supported, but names can be converted to strings, formatted, then converted back to names.


  • Sound
A name of a sound as defined in SNDINFO. GZDoom cannot read audio file names directly; only sounds exposed to SNDINFO can be utilized in audio functions (such as A_StartSound and others).
Sounds are treated similarly to strings, so they can be formatted as well.


  • StateLabel
Contains the name of a state sequence label. Should be enclosed with double quotation marks: "MyStateLabel".
These are NOT strings. Cannot be directly converted to strings or vice versa. The only method currently that can convert strings to StateLabel is FindStateByString.
These are NOT state pointers. A pointer to the first state under the specified state label can be obtained with FindState("MyStateLabel") or ResolveState("MyStateLabel") (depending on thecalling context).

A special case should be noted with null and "Null", the key difference being using "" around it or not:

  • null means "no state" and should be used if an actor should not perform a jump.
  • "Null" is an actual name of a state label defined in the base Actor class, and it destroys the calling actor after 1 tic. Should be used if the actor should be destroyed. Do not confuse this with null. This is safe to use when a jumping function is inside an IF statement — the actor will not be destroyed, since they are treated as booleans instead of actual jumps for testing purposes only.


  • Color
Used to record a a color either defined in the X11R6RGB lump or a hexidecimal value, or a directly specified ARGB value.
Has 4 components: a (alpha), r (red), g (green), b (blue) as 0-255 values. Alpha is not used in some cases, for example in functions that utilize alpha as a separate value/property.

Color can be defined as a string, a series of 0-255 values, or a hex code. In all of these cases alpha can be specified or omitted.

color col0 = "red"; //red
color col1 = color(255, 255, 0, 0); //red, alpha explicitly specified
color col2 = color(255, 0, 0); //red
color col3 = 0xFFFF0000; //red, alpha explicitly specified
color col4 = 0xFF0000; //red

NOTE: Several actor properties can be read only after the mask has been cleared, such as bloodcolor.

Color bl = (bloodcolor & 0xffffff); //Six 'f's, no more, no less!

// Alpha, red, green, and blue from left to right.
// Can also access directly as demonstrated.
Color regrbl = Color(255, 128, 192, 255); 
regrbl.a = 255;
regrbl.r = 128;
regrbl.g = 192;
regrbl.b = 255;


  • TextureID
Contains the integer ID of a texture, all graphics have TextureIDs, not just map textures. See TextureID.
Textures can be obtained and otherwise managed with TexMan.

Class types

  • class<myclass>
Used for holding class names and passing said names into places where a function may be expecting a legitimate class for its functionality. If a class that does not exist is assigned to it, GZDoom will throw an error message. Note that an invalid class is not the same thing as null.
class<Actor> proj = 'RocketProjectile';
if (CountInv('GrenadeAmmo'))
    proj = 'GrenadeProjectile';

Function references

As of GZDoom 4.12, references to functions can be made, both static and non-static. Virtual functions are currently not referenceable so for non-static functions they cannot be virtual. They take the following syntax:

function<[scope] [return types]([parameter types])> MyFunction;
  • [scope] is the scope of the function. This can be play, ui, or clearscope. Note that this does not scope cast the function itself, it's merely used to check to make sure the function is valid.
  • [return types] are the data types of the return values. They're comma separated should there be more than one. void is used for functions with no return values.
  • [parameter types] are the data types of the parameters, comma separated. If there are no parameters, this can be left empty as ().
There are two ways to assign them:
  • MyClass.FunctionName
Direct assignment. Note that this can only be done with classes that the ZScript compiler actually knows about at compile time i.e. this can't be used with classes outside of your archive that haven't been parsed yet. The benefit of this method is that it can allow for error checking at compile time instead of needing to null check at run time.
function<play void(Actor)> func = Actor.A_Pain;
  • FindFunction("ClassName", "FunctionName")
A more generalized method for grabbing a reference to a function. This returns a function<void> reference so it must be type casted manually:
let func = (function<play void(Actor)>)(FindFunction("Actor", "A_Pain"));
Note: For non-static functions, the first parameter of them needs to be the class type of self since this is also treated as a parameter. This means they will always have at least one parameter. Also important is that the class type must be the exact class the function is defined within. For instance, if a non-static function is defined in MyClass, the type of self must also be MyClass when getting a reference to it.
function<void> is a special untyped function reference that can be used to generically pass and store any kind. It must be type casted to the correct kind of function before it can be used (see the above example with FindFunction()).
The function can be invoked via its Call() method. It accepts the same parameters and returns the same return values as the function it's referencing as though that function were directly invoked.
function<clearscope bool(Actor, int, Sound)> func = Actor.IsActorPlayingSound;
if (func.Call(myActor, CHAN_BODY, -1))
    // ...
Note: Function references have no concept of default values and all parameters must be passed in full when invoking the function.
Any sort of invalid type casting of a function will set the reference to null, allowing it to be properly null checked. Properties via the property keyword can also be used on Actors but they must use the MyClass.MyFunction syntax when defining its value within the default block.

Member Variable Only Types

Certain data types in ZScript are valid but will only work when stored as a member variable. If used within a function they are converted to the appropriate data type as listed below. Once they're done being used, the result in them will be converted back to the assigned data type. This can be used to save memory e.g. on any fields in your class. These data types should not be declared within functions as they're only intended to be used for member variables. These types include:

  • int8
Stores an 8-bit and 16-bit integer respectively
Converts to int
  • uint8
Stores an 8-bit and 16-bit unsigned integer respectively
Converts to uint
  • float
Stores a 32-bit floating-point value
Converts to double
  • FVector2
Uses single precision instead of double precision for its members
Converts to Vector2/Vector3/Vector4
Note: Currently trying to dot/cross product with a regular Vector2/3/4 will not work.
  • FQuat
Uses single precision instead of double precision for its members
Converts to Quat
class MyClass
    float myFloat; // this is a 32-bit float

    double AddFloats(double a, double b) // all floating-point variables in functions should be doubles
        myFloat = a + b; // myFloat is converted to a double
        return myFloat;
    // after this function is done, the value in myFloat will be converted back to a 32-bit float


Access Modifiers

Access modifiers determine what fields and functions classes are capable of seeing from another class. If no modifier is specified then it is treated as public: every class has access to that field or function.

  • protected - Only this class and its child classes have access to this
  • private - Only this class has access to this

Scope Modifiers

Scope modifiers determine which scope to place a class, struct, field, or function in. For fields (including structs) and functions it will automatically inherit the scope of the class/struct it's defined in, but this can be changed by manually specifying a different scope. Anything that inherits from Thinker (e.g. Actor) will be in the play scope. By default classes or structs are placed in the data scope if no modifier is specified.

  • virtualscope - Any non-static function marked with this will assume the scope of the class or struct it's being called from
  • clearscope - If a function is in either the play or ui scope, this will set it back to being data scoped
  • play - Any field, function, class, or struct marked with this will be put in the play scope
  • ui - Any field, function, class, or struct marked with this will be put in the ui scope
class MyClass play

// if defined as a field in a play scoped class this will still be ui scoped
struct MyStruct ui
// this will become play scoped if defined as a field in a play scoped class
struct MyStruct2

ui int myField;
virtualscope void MyFunction() {}

Class modifiers (New from 4.12.2)

Class modifiers allow for altering how the inheritance of ZScript classes can be handled.

class ParentClass
	int Variable;

class ChildClass : ParentClass final //Final version of this class.
	int NewVariable;

//This will no longer work, and create a compile error instead.
class GrandchildClass : ChildClass
	int NewerVariable;
  • sealed (class1, class2, etc...) - Limits inheritance of a class to only the specific child classes defined.
class ExclusiveParent sealed (Child1, Child2)
	int Variable;

class Child1 : ExclusiveParent
	int NewVariable;

class Child2 : ExclusiveParent
	int NewerVariable;

//No other classes can be derived from ExclusiveParent anymore, because they are not part of the sealed (class1, class2, class3...) list.
class BastardChild : ExclusiveParent
	int NewererVariable;

Function modifiers

Functions can be optionally declared with action, static and virtual modifiers. See Function types.


The transient keyword can be used to mark a field as non-serializable. Non-serializable fields will not be stored in save files. This can be useful for certain types that cannot be saved such as CVars and SecPlanes. It can also be useful if you want to force data to be cleared every time the game is reopened.

transient CVar myCVar; // this allows CVars to be safely stored as a field


Note: starting with 4.11.0, the internal modifier can be used outside of the engine archive.

If a field is set to readonly but your ZScript still needs to modify it, internal can be used to allow this without having to either obscure the field or give full write access. Code outside of the archive the field is in will still only be able to read from it and not write.

readonly internal int modSpecificValue;

Internal Engine Modifiers

These modifiers can't be used by modders but are documented here for game developers using GZDoom who wish to expand the internal pk3 for their games.

  • native
For fields, this is declared and used by the engine itself. For functions, this method is defined within the engine. For classes and structs, these types are defined and used by the engine itself.
Note: Native struct variables store a reference to a struct instead of being allocated on the stack directly. As such, they can be returned, assigned, and used in dynamic arrays, but cannot be created manually from within ZScript. Special care is needed as any internal struct being exported must have its size and alignment defined, otherwise the VM will not know how to properly manage it in memory.
class EngineClass native

struct EngineStruct native

native int engineValue;
native void EngineFunction();
  • vararg
This specifies that a native function takes a variable amount of arguments. Putting ... as the last parameter marks when the variable arguments start. No other parameters can be defined after this point.
native vararg void MyFunction(int arg1, int arg2, ...);
  • @
Internal engine structs can be defined to either be stored by their value or by their reference (referred to as native) within the VM. In some cases a struct is defined as native but an internal variable or array stores it by its value. @ marks that a native struct in this case should not be stored by its reference.
native Array<@NativeStruct> NativeArray;
native @NativeStruct NativeField;


The readonly keyword can be used to make it so an Actor field cannot be written to. This can be useful for creating pseudo constant values that you might want to change on a per-Actor basis via their properties. It can also be used to pass readonly reference handles to functions. Readonly fields must be set in the Default block as a property.

readonly int prop;

// references set as readonly use readonly<T> syntax
void MyFunction(readonly<Actor> mo) {}

For developers using GZDoom to create their games, readonly can also be used as a way to pass information from the engine to the front end without allowing modders to directly modify it. For instance, radius is set to readonly in ZScript but can still be modified within the engine itself. This allows for easy read access while forcing an API for write access.


The meta keyword is a special modifier that marks an Actor field as both static and readonly. Static in this case means the field is not stored on each individual Actor but instead shared in a single spot in memory across all of them. If you have values that aren't tied to a particular instance of an Actor, this can be used to save memory. A virtual getter function can be created to allow classes to modify it conditionally. Due to the nature of being readonly, this can only be set via the Default block as a property.

meta int GibHealth;

virtual int GetGibHealth()
	if (GibHealth != int.min)
		return -abs(GibHealth);
		return -int(GetSpawnHealth() * gameinfo.gibfactor);

Function Const

Unlike variable consts, the const keyword for non-static functions denotes that the function does not modify the object's fields in its body. Unlike traditional C++ this does not actually prevent the function from modifying fields but instead acts like a hint that it won't do so. As a result this should only be used with functions where nothing but local variables are being modified. It's often used for getter functions so that they can be called from any scope.

clearscope bool GetValue() const {} // This should be paired with clearscope to denote it won't modify the play or ui scopes


Arrays behave like their C++ counterparts, including multi-dimensional support.

Dynamic Arrays

Dynamic arrays are similar to local arrays but can be resized at any time. They are similar to vectors in C++.

Array<int> myNumbers;

Local Arrays

Local arrays can be defined with a set number of index spots, but cannot be initialized until after their declaration. Changing the array's contents must be done inside an anonymous or named function. These can also be declared inside of said functions for temporary existence.

int MyArray[2];
MyArray[0] = 5;
MyArray[1] = 10;

Constant Arrays

Constant arrays are different from normal constants.

  • Can be defined in (anonymous) functions
  • Must have all their fields initialized immediately.
  • Must have a type, and the static word present.
// static const <type> <name>[] =
static const Color SecondaryColor[] =
    "Blue" // Unlike enums, the last member must not have a comma.

Linked lists

Linked lists are a structure somewhat similar to arrays, but new linked lists cannot be created in ZScript. However, some existing linked lists are exposed to ZScript and can be operated on. The two most common linked lists are Inv stored in Actor (the list of all Inventory items in said actor's inventory) and psprites in PlayerInfo (stores all currently used PSprite instances).

In contrast to arrays, elements of a linked list cannot be accessed directly with an index. Instead, the class that has a linked list has a pointer to the first element of the linked list, and each element of the list has a pointer to the next element.

Linked lists can be iterated over by using a FOR loop. The most commonly used linked list is, arguably, Actor's inventory, so iterating over it would look as follows:

for (let item = <actorpointer>.Inv; item != null; item = item.Inv)
    // do something with 'item'

In this example <actorpointer> is a pointer to an actor who is holding some items, and <actorpointer>.Inv is a pointer to the first item in their inventory.


The following are special types of variables of greater complexity.

  • Similar to their C++ counterpart, contains data of different types. Can also contain functions.
  • An internal struct which can be used to gather information about an actor's state.


Unlike C++ and DECORATE, ZScript's constant non-arrays do not have a type to be given -- they auto resolve by themselves based on their usage. Only integer, double and string constants are supported.

const CON1 = 1; //int
const CON2 = 2.5; //double
const CON3 = "Stringify me, cap'n!"; //string (using "")

See Also