Attributes

This page describes all the attributes that can be used to customize actions.

Type Attributes

Attribute	Description
ActionCategory	Sets the action's category in the Action Browser.
ActionDescription	Sets the description used in the Action Browser and Action Editor.
ConvertibleGroup	Groups actions for quick swapping in the Action Editor.
HasSceneGUI	Indicates the action has OnSceneGUI editing. See Scene GUI Drawer.

Field Attributes

Attribute	Description
Tooltip	Used as action parameter tooltip.
Optional	Marks an action parameter as optional. By default, fields are required.
DefaultValue	Sets the default value when an action is created or reset.
CanBeNullOrEmpty	Allows a required field to be null or empty.
ConvertibleName	Used to match fields in a ConvertibleGroup when names differ.
ActionTarget	Indicates a field is the "target" for drag-and-drop menus.
RequiredComponent	Specifies a required component for the field.
ActionHeader	Shows a header above a field in the editor, like Unity's `HeaderAttribute`.
Note	Shows a HelpBox above a field for prominent info.
DisplayOrder	Overrides field order in the UI. Lower numbers appear first.

Variable Field Attributes

Attribute	Description
OwnerDefaultValue	Field defaults to `Owner`
NotOwnerDefaultValue	Field should NOT default to `Owner`
WriteOnly	Marks a field as write only.
VarRange	Like Unity's RangeAttribute but for variable fields.
VarSlider	Displays a slider for variable fields. Values can exceed the slider range.
HideDebugValue	Hides the debug value for this field. See Debug Variable Values.
DefaultName	Sets a custom name when auto-adding a variable or event.
LayerValue	Marks an `IntegerVar` as a Layer value and shows the appropriate UI.
TagValue	Marks a `StringVar` as a Tag and shows the appropriate UI.
MatchType	Ensures the field matches the type of another field.
BaseType	Base type assignable to a variable field.

Event Field Attributes

Attribute	Description
GlobalEvent	Marks an event field as requiring a Global Event.
BroadcastEvent	Marks an event field as one that will be broadcast.
EventNotSent	Indicates the event is not sent.
DisableEventNotUsed-InTransitionsError	Disables error check on an `EventRef` field if the event is not sent.

List Field Attributes

Attribute	Description
ArrayElementLabel	Overrides the label for array/list elements in the UI.
ArrayElementTooltip	Tooltip for individual array/list elements.
HideArrayLabels	Hides element labels in the UI.

Details

Below you'll find detailed descriptions for each attribute.

ActionCategory

Sets the action's category in the Action Browser.

Parameter	Type	Description
name	string	Name of an existing or new category. Use "/" to nest categories. `HutongGames.PlayMaker.Category` defines common categories.

ActionDescription

Sets the description used in the Action Browser and Action Editor.

Parameter	Type	Description
summary	string	A short summary of the action.
details	string	(Optional) More detail shown in the Action Browser.

ConvertibleGroup

A named group of actions that are all swappable in the Action Editor.

For example, OnCollisionEnter and OnCollisionExit actions are both in the "OnCollision" group.

Parameter	Type	Description
name	string	The name of the convertible group.

HasSceneGUI

Indicates that an Action has OnSceneGUI editing.

See Scene GUI Drawer

Describes an action field. Shown in rollover tooltips and summaries.

Parameter	Type	Description
tooltip	string	A short description of the action field.

Optional

Marks an action parameter as optional.

Upgrade Note

Action fields are required unless marked as optional.
This is a change from PM1 where parameters where optional unless marked as required.

WriteOnly

Marks an action field as write only. The field should be a Ref: FloatRef, StringRef, etc. WriteOnly means you can only select writable variables for the parameter.

DefaultValue

Defines the default value of an action field when an action is created or reset. Otherwise the field uses the default value for the data type (0 for float, null for GameObject, etc.)

The value can be:

A constant value compatible with the field type: 0, 1f, "Hello"...
A string representing a named value: "Vector3.up", "Vector2.one", "Color.red", "Quaternion.identity"
A string starting with ~, representing a named PlayMaker value: "~MainCamera", "~Vector3Up"
An enum name as a string for enum fields: "Z", "UseGlobal"
A comma-separated value list for some struct types: "0,1", "0,1,2", "0,0,10,20"
A typeof(...) value for supported type-reference fields
DefaultValueAttribute.None to default a field to None

Tip

Because constants and globals are just assets in the project, you can include project specific default values in custom actions.

Supported Formats

Here are the main formats supported by DefaultValue:

Format	Example	Notes
Primitive or literal value	`[DefaultValue(1f)]`	Works for compatible literal values such as `int`, `float`, `bool`, and strings.
Named built-in value	`[DefaultValue("Vector3.up")]`	Useful for vectors, colors, quaternions, and similar values.
Named PlayMaker value	`[DefaultValue("~MainCamera")]`	Uses a named PlayMaker value instead of a literal constant.
Enum value by name	`[DefaultValue("Z")]`	Useful when the field type is an enum.
Comma-separated struct value	`[DefaultValue("0,0,10,20")]`	Supported for some multi-value structs.
Type reference	`[DefaultValue(typeof(MyBlockType))]`	Used for supported type-reference or block fields.
None sentinel	`[DefaultValue(DefaultValueAttribute.None)]`	Sets the field to `None` instead of a concrete value.

Named Values

Named values are string defaults that resolve to known values at edit time.

Common examples include:

"Vector3.zero", "Vector3.one", "Vector3.up"
"Vector2.zero", "Vector2.one", "Vector2.right"
"Color.white", "Color.red", "Color.cyan"
"Quaternion.identity"
"Physics.DefaultRaycastLayers"

You can also use HTML color strings with Color and Color32 fields:

"#FF0000"
"#FF0000FF"

Comma-Separated Values

Some struct types can be created from comma-separated values:

Vector2: "1,2"
Vector3: "1,2,3"
Vector2Int: "1,2"
Vector3Int: "1,2,3"
Rect: "0,0,10,20"
RectInt: "0,0,10,20"
BoundsInt: "0,0,0,10,20,30"

This is useful when there is no simple named value for the default you want.

Examples

[DefaultValue(1f)]
public FloatVar speed;

[DefaultValue("Vector3.up")]
public Vector3Var direction;

[DefaultValue("Color.cyan")]
public ColorVar debugColor;

[DefaultValue("Z")]
public AxisDirectionVar facingAxis;

[DefaultValue("0,0,10,20")]
public RectVar viewport;

[DefaultValue("~MainCamera")]
public GameObjectVar cameraObject;

[DefaultValue(DefaultValueAttribute.None)]
public BoundsIntVar bounds;

OwnerDefaultValue

Specifies that the field's value should default to Owner.

Tip

There are some internal rules to identify Owner fields.
You only need to use the OwnerDefaultValue attribute if the field is not found automatically.

NotOwnerDefaultValue

Specifies that the field should NOT default to Owner.

Use this to override the internal rules if needed.

CanBeNullOrEmpty

Indicates that a required field is allowed to be null or empty.

For example, to indicate that a Unity Object field can be null, or a StringVar field can be empty.

VarRange

Similar to the Unity RangeAttribute but for FloatVar and IntegerVar fields.

Parameter	Type	Description
min	float	The lower limit of the range.
max	float	The upper limit of the range.

VarSlider

Displays a slider next to FloatVar or IntegerVar fields. The value field accepts values outside the slider range.

Parameter	Type	Description
min	float	The lower limit of the range.
max	float	The upper limit of the range.

ConvertibleName

Name that can be used to match fields in a ConvertibleGroup.

Parameter	Type	Description
name	string	The name used to match fields in a convertible group.

Fields in a convertible group are normally matched by name. Use this attribute if fields are convertible but have different names.

For example, ListGetNextItem and ListGetRandomItem have items fields with different names but are convertible.

DefaultName

Used when auto-adding a variable or event.

Parameter	Type	Description
name	string	The default name used when auto-adding a variable or event.

Normally the auto-created variable or event uses the field name. Use this attribute to define a custom name instead.

ActionTarget

Indicates that a field is the "target" for an action. For example, if placed on a GameObjectRef it indicates that the action targets GameObjects.

Action targets are used to populate drag and drop menus. For example, when dropping a GameObject into the action list, we look for all actions that target a GameObject.

Tip

There are some internal rules to identify target fields.
You only need to use the ActionTarget attribute if the field is not found automatically.

RequiredComponent

Specifies that the field requires a specific component.

Parameter	Type	Description
componentType	Type	The required component.

Tip

There are some internal rules to identify required components.
You only need to use the RequiredComponent attribute if the field is not found automatically.

ActionHeader

Show a header above a field in the action editor, similar to the Unity HeaderAttribute.

Use this to organize action fields into sections.

Parameter	Type	Description
label	string	The header title.

Note

Show a HelpBox above a field in the action editor.

Use this to add extra information that should be more prominent than a tooltip.

Parameter	Type	Description
message	string	The message to show in the HelpBox.
messageType	HelpBox.messageType	What kind of HelpBox to show.

DisplayOrder

Overrides the default order of the field in the UI.

By default, fields are shown in the order they are declared in. Sometimes you need to override this order. For example, when using a base class you often want the fields declared in the base class to appear before fields in the derived classes.

Parameter	Type	Description
order	int	Smaller numbers are sorted first. For example: -1000 should guarantee that a field appears first. 1000 should guarantee that it appears at the end.

HideDebugValue

Hide the debug value for this field.

See Debug Variable Values.

LayerValue

Marks an IntegerVar as containing a Layer value, and shows the appropriate UI.

TagValue

Marks a StringVar as containing a Tag, and shows the appropriate UI.

Event Field Attributes

Attributes for EventRef fields.

GlobalEvent

Marks an event field as requiring a Global Event.

The event selector will only shows global events.

BroadcastEvent

Marks an event field as an event that will be broadcast.

You can only select global events for this field.

EventNotSent

Indicates that the event is not sent. This disables any "not used" errors on the field.

DisableEventNotUsedInTransitionsError

Disables the error check on an EventRef field.

Sometimes you want to use an EventRef field for an event that will not be sent.

MatchType

Makes sure the field matched the type of another field. For example, in GetComponent, the StoreResult type needs to match the type of the selected ComponentType.

Parameter	Type	Description
fieldName	string	Name of the action field to match.

BaseType

Base type assignable to a variable field.

Parameter	Type	Description
type	Type	The field can contain variables of this type or subclasses of this type.

ArrayElementLabel

Use on a list field. Overrides the name of an element, normally Element 0, Element 1, etc.

Parameter	Type	Description
name	string	The name to use as a label.

ArrayElementTooltip

Use on a list field. Tooltip text to use on individual elements in the UI.

Parameter	Type	Description
text	string	Text to use in the tooltip.

HideArrayLabels

Used on a list field. Hides element labels in the UI.