Physics Area Primitive component reference

Explore the properties you can use to configure a Physics Area Primitive component in the Unity Editor using 2D Physics Core.

Read time 3 minutes

Last updated 14 days ago

Explore the properties you can use to select a shape in a 2D Physics Core object. For more information, refer to Add physics to a GameObject with 2D Physics Core.

Note

This documentation is about using Pose, Area, and Constraint components. To use 2D physics in the Unity Editor using components like the Rigidbody 2D component, refer to 2D physics instead.

Pose

Property	Description
Pose Source	Sets how Unity finds the Physics Pose component this area attaches to. The options are: Auto: Searches this GameObject and its parents for a Physics Pose component. Custom: Uses the Physics Pose component from the GameObject you set in the Pose Target property.
Pose Target	Attaches this area to the Physics Pose component on this GameObject. Drag a GameObject with a Physics Pose component from the Hierarchy window to this property, or select the picker (⊙). This property is available only if you set Pose Source to Custom.
Refresh Pose	Searches this GameObject and its parents again for a Physics Pose component. This property is available only if you set Pose Source to Auto.

Geometry

The properties in this section set the shape this component generates. Only the properties for the shape type you select in Shape Type are used; the properties for every other shape type are kept, but ignored.

Property	Description
Shape Type	Sets the shape. The options are: Circle Capsule Segment Polygon Chain Segment: A Segment with additional invisible points that make collisions more accurate.
Geometry Asset	Sets an asset that sets the values of the geometry properties for the selected Shape Type. By default, this property is empty, and Unity stores the values inside the component. To use a geometry asset instead, drag a matching geometry asset from the Project window to this property, or select the picker (⊙).
Make Asset	Converts the geometry stored in the component for the selected Shape Type into a geometry asset, and assigns it to Geometry Asset. This property is available only if you don't set a Geometry Asset.
Make Local	Removes the Geometry Asset and copies its values into the component's local geometry for the selected Shape Type. This property is available only if you set a Geometry Asset.

For more information about the properties available for each shape type, refer to the following:

These properties are available if you set Shape Type to Chain Segment:

Property	Description
Geometry Asset	Sets an asset that sets the values of the properties in this section. By default, this property is empty, and Unity stores the values inside the component. To set a geometry asset instead, drag a Physics Chain Segment Geometry asset from the Project window to this property, or select the picker (⊙).
Make Asset	Converts the local chain segment geometry into a Physics Chain Segment Geometry asset, and assigns it to Geometry Asset. This property is available only if you don't set a Geometry Asset.
Make Local	Removes the Geometry Asset and copies its values into the component's local chain segment geometry. This property is available only if you set a Geometry Asset.
Segment	Sets the points that form the line.
Point 1	Sets the start point of the line.
Point 2	Sets the end point of the line.
Ghost 1	Sets the invisible point that extends from Point 1. Unity uses this point to make collisions more accurate.
Ghost 2	Sets the invisible point that extends from Point 2. Unity uses this point to make collisions more accurate.

Transformation

Property	Description
Position	Offsets the position of the area, relative to the Position property of the GameObject's Transform component.
Rotation	Offsets the rotation of the area in degrees, relative to the Rotation property of the GameObject's Transform component.
Scale	Offsets the scale of the area, relative to the Scale property of the GameObject's Transform component.
Scale Radius	Adjusts the radius of the object using both the Scale property in this section and the Scale property of the GameObject's Transform component. This property is available only if you set Shape Type to Circle, Capsule, or Polygon.

Definition

The properties in this section set the properties of the shape.

Property	Description
Definition Asset	Sets an asset that sets the values of the properties in this section. By default, this property is empty, and Unity stores the values inside the component. To set a definition asset, drag a Physics Area Definition asset from the Project window to this property, or select the picker (⊙).

Definition Overrides

The properties in this section override the properties from the Definition Asset, or the local values if no Definition Asset is assigned.

Property	Description
Contact Asset	Sets a Physics Contact Filter asset that overrides the Contact Filter properties.
Material Asset	Sets a Physics Surface Material asset that overrides the Surface Material properties.

Contact Filter

The properties in the Contact Filter section determine which other shapes the area collides with. For more information, refer to Configure collisions between 2D Physics Core objects.

Property	Description
Categories	Sets the layers this shape belongs to.
Contacts	Sets the layers this shape collides with.
Group Index	Assigns the shape to a group, and overrides the Categories and Contacts properties. Use the following values: `0` : Assigns no group. The shape uses the Categories and Contacts properties to determine collisions. Positive value: The shape always collides with other shapes that have the same Group Index. Negative value: The shape doesn't collide with other shapes that have the same Group Index.

Surface Material

The properties in the Surface Material section determine how the shape interacts with other shapes.

Property	Description
Friction	Sets the coefficient of friction for this collider. A value of 0 means no friction, like ice. A value of 1 means very high friction, like rubber. The default is 0.6.
Bounciness	Sets how bouncy the surface is, and how much other colliders bounce off it. A value of 0 means the surface isn't at all bouncy, like soft clay. A value of 1 means the surface is very bouncy, like rubber. The default is 0.
Friction Mixing	Determines the method Unity uses to mix the friction of two objects when they make contact. The options are: Average: Uses the average of the two values. Mean: Uses the geometric mean of the two values. The geometric mean multiplies the two values then returns the square root. Multiply: Multiplies the two values together. Minimum: Uses the smaller value. Maximum: Uses the larger value.
Bounciness Mixing	Determines the method Unity uses to mix the bounciness of two objects when they make contact. The options are: Average: Uses the average of the two values. Mean: Uses the geometric mean of the two values. The geometric mean multiplies the two values then returns the square root. Multiply: Multiplies the two values together. Minimum: Uses the smaller value. Maximum: Uses the larger value.
Friction Priority	Determines which shape contributes its Friction Mixing mode when two shapes come into contact. Unity uses the Friction Mixing mode from the shape with the highest Friction Priority value. If the two shapes have the same Friction Priority value, Unity uses the highest `SurfaceMaterial.MixingMode` enumeration value from the two shapes.
Bounciness Priority	Determines which shape contributes its Bounciness Mixing mode when two shapes come into contact. Unity uses the Bounciness Mixing mode from the shape with the highest Bounciness Priority value. If the two shapes have the same Bounciness Priority value, Unity uses the highest `SurfaceMaterial.MixingMode` enumeration value from the two shapes.
Rolling Resistance	Sets how resistant the shape is to rolling. The range of values is 0 to 1, where 0 means no rolling resistance and 1 means full rolling resistance.
Tangent Speed	Sets the speed the surface moves other objects that come into contact with it, in meters per second. For example, if you set Tangent Speed to 5, the surface acts like a conveyor belt that moves objects along the surface at 5 meters per second. You can use a positive or negative value to set the direction of movement.
Custom Color	Overrides the color Unity uses to draw the debug visualization of the shape. The alpha value is ignored. The default is `Color.Clear` , which is black with an alpha of 0, and means Unity uses different colors to represent the current state of the shape. For more information, refer to Visualize and edit 2D Physics Core scenes.

Other properties

Property	Description
Density	Sets the density in kg/m^2. The default is 1. Use this property to create a hollow shape for example.
Is Trigger	Enables the shape going through other shapes without generating a collision response. Instead, the shape generates a trigger event when another shape overlaps. For more information, refer to Introduction to collision in 2D Physics Core.
Trigger Events	Produces a trigger event when the shape starts and ends overlapping another shape that has its Is Trigger property enabled. To fetch events, refer to `PhysicsWorld.triggerBeginEvents` .
Contact Events	Produces a contact event when the shape starts and ends contact with another shape. This property has no effect if the shape is attached to a body set to Static. To fetch events, refer to `PhysicsWorld.contactBeginEvents` .
Hit Events	Produces a hit event when the shape collides with another shape. This property has no effect if the shape is attached to a body set to Static. To fetch events, refer to `PhysicsWorld.shapeHitEvents` .
Contact Filter Callbacks	Calls the `IContactFilterCallback` method of the shape if it makes contact with another shape, so you can run your own code that determines whether the shapes should collide.
Pre Solve Callbacks	Calls the `OnPreSolve2D` method of the dynamic body before Unity calculates the collision response, so you can run your own code.
Start Static Contacts	Produces a contact event if the shape is attached to a body set to Static, and the shape makes contact with another shape. Enabling this property can reduce performance if you have many static shapes.
Start Mass Update	Updates the mass of the body when the shape is created. Disabling this property can improve performance if you add multiple shapes to the same body, but you must call `ApplyMassFromShapes` to recalculate after you add a shape.
World Drawing	Draws the shape when Unity draws the debug visualization of the world. For more information, refer to Visualize and edit 2D Physics Core scenes.

Mover Data

The properties in this section control how the area reacts to

PhysicsWorld.CastMover

geometry that collides with it.

Property	Description
Push Limit	Sets the amount the shape pushes against the geometry.
Clip Velocity	Enables the shape clipping the velocity of the geometry.

Callbacks

Property	Description
Callback Source	Sets the callback method the area calls when it makes contact with another area. The options are: Off: Calls no callbacks. Area: Calls the `PhysicsAreaCallbacks.IContactCallback` or `PhysicsAreaCallbacks.ITriggerCallback` method on the Callback Target object. Unity passes this method the Physics Area component that made contact. Shapes: Calls the `PhysicsCallbacks.IContactCallback` or `PhysicsCallbacks.ITriggerCallback` method on the Callback Target object. Unity passes this method the specific shape that made contact. Events: Calls a method or sets a parameter you select in the On Contact Begin, On Contact End, On Trigger Begin, or On Trigger End section. For more information, refer to Collisions and interactions in 2D Physics Core.
Callback Target	Sets the object that receives physics callbacks. This property is available only if you set Callback Source to Area or Shapes.
Areas Only	Calls callback methods only when the other shape also belongs to an area. Disable this property if you create shapes using the `U2D.Physics` API instead of a Physics Area component. This property is available only if you set Callback Source to Area or Events.

Event settings

The properties in this section set the specific method this area calls or the parameter it sets when contact begins or ends. This section is available only if you set Callback Source to Events, and controls the behavior of one of the following methods of the component:

On Contact Begin (ContactBeginEvent)

and

On Contact End (ContactEndEvent)

, if Is Trigger is disabled.

On Trigger Begin (TriggerBeginEvent)

and

On Trigger End (TriggerEndEvent)

, If Is Trigger is enabled.

Property	Description
Activation	Sets when the object activates the callback method or parameter. The options are: Off: Doesn't activate the callback method or parameter. Editor and Runtime: Activates the callback method or parameter in the Unity Editor and at runtime. Runtime Only: Activates the callback method or parameter only at runtime.
Object	Sets the object with the parameter to update or method to call. Drag any object from the Hierarchy or Project windows to this property, or select the picker (⊙).
Functions	Sets the parameter to update or the method to call. Select a parameter or method from the Object, its components, or its script methods. You can set the parameter value to update to, or the method parameters to use.
Add (+)	Adds a new callback method to the list.
Remove (-)	Removes the selected callback method from the list.

User Data

Use the properties in this section to add your own data to the component, and read it using the

U2D.Physics

API. For more information, refer to Add custom data to a 2D Physics Core object.

Property	Description
Object	Sets a custom object. Drag any object from the Hierarchy or Project windows to this property, or select the picker (⊙).
Physics Mask	Sets a custom set of enabled and disabled layers. For more information, refer to Configure collisions between 2D Physics Core objects.
Float	Sets a custom floating-point number.
Int	Sets a custom integer.
Int 64	Sets a custom 64-bit integer.
Vector 3 Int	Sets a custom 3D vector of integers.
Bool	Sets a custom Boolean value.

Info

This section displays information about the component. You can't directly edit the properties in this section.

Handle

Property	Description
Valid	The state of the object. True means the object is in the simulation.
World	The index number of the world the object belongs to. The default is 0, which is the default world.
Index	The index number of the object in the world.
Generation	The number of times Unity has used the same Index for different objects.

Callbacks

This section is visible only if you set Callback Source to a value other than Off.

Property	Description
Contact Begin	How many times a contact-begin callback was dispatched to a valid receiver this session. This property is visible only if the area's active definition isn't a trigger.
Contact End	How many times a contact-end callback was dispatched to a valid receiver this session. This property is visible only if the area's active definition isn't a trigger.
Trigger Begin	How many times a trigger-begin callback was dispatched to a valid receiver this session. This property is visible only if the area's active definition is a trigger.
Trigger End	How many times a trigger-end callback was dispatched to a valid receiver this session. This property is visible only if the area's active definition is a trigger.

Other properties

Property	Description
Shape Count	The number of shapes in this area.

Physics Area Primitive component reference

Pose

Property

Description

Geometry

Property

Description

Property

Description

Transformation

Property

Description

Definition

Property

Description

Definition Overrides

Property

Description

Contact Filter

Property

Description

Surface Material

Property

Description

Other properties

Property

Description

Mover Data

Property

Description

Callbacks

Property

Description

Event settings

Property

Description

User Data

Property

Description

Info

Handle

Property

Description

Callbacks

Property

Description

Other properties

Property

Description

Additional resources