# Physics Constraint Distance component reference > Explore the properties you can use to keep two connected 2D Physics Core objects a certain distance apart. Explore the properties you can use to keep two connected 2D Physics Core objects a certain distance apart. For more information, refer to [Add a constraint](/engine/6000.7/manual/unity2d/2d-physics-api/connect-objects/create-constraint.md). > **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](/engine/6000.7/manual/unity2d/2d-physics.md.md) instead. ## Pose | **Property** | **Description** | | ----------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Pose A Source** | Sets how Unity finds the first object this constraint connects to. The options are:**Auto**: Searches this GameObject and its parents for a Physics Pose component.**Custom**: Uses the Physics Pose component you assign to **Pose A Target**. | | **Pose A Target** | Sets the first Physics Pose component this constraint connects to. This property is available only if you set **Pose A Source** to **Custom**. Drag a GameObject with a Physics Pose component from the **Hierarchy** window to this property, or select the picker (**⊙**). | | **Pose B Target** | Sets the second object this constraint connects. Drag a GameObject with a Physics Pose component from the **Hierarchy** window to this property, or select the picker (**⊙**). | | **Refresh Poses** | Refreshes **Pose A Target** and **Pose B Target** and recreates the constraint. | ## Definition | **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 Constraint Distance Definition asset from the **Project** window to this property, or select the picker (**⊙**). For more information, refer to [Share properties across multiple 2D Physics Core components](/engine/6000.7/manual/unity2d/2d-physics-api/properties/definitions.md). | | **Auto Distance** | Keeps the distance between the objects when Unity creates the constraint. If you enable this property, the **Distance** property has no effect. | | **Distance** | Sets the target distance between the two connected objects. This property is available only if you disable **Auto Distance**. | | **Collide Connected** | Allows the shapes on the two connected objects to collide with each other and create collision or trigger events. By default, the constraint prevents this. For more information, refer to [Collisions and interactions in 2D Physics Core](/engine/6000.7/manual/unity2d/2d-physics-api/interactions.md). | ### Anchors Set where each end of the constraint attaches. **Local Anchor A** attaches to the first object and **Local Anchor B** attaches to the second object. Each anchor has the following properties. | **Property** | **Description** | | ------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | **Auto** | Automatically calculates the anchor position and rotation from the positions of the two objects when Unity creates the constraint. As a result, both anchors line up in world space. | | **Position** | Sets the position of the anchor, relative to the position of the object it attaches to. This property is available only if you disable **Auto**. | | **Rotation** | Sets the rotation of the anchor in degrees. This property is available only if you disable **Auto**. | ### Spring | **Property** | **Description** | | ---------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Enable Spring** | Makes the constraint act as a spring, so it stretches and compresses to try to reach the target distance. The strength of the pull is proportional to the current distance between the objects. If you disable this property, the constraint is rigid, and **Enable Motor** and **Enable Limit** have no effect. | | **Spring Frequency** | Sets the stiffness of the spring in Hertz (cycles per second). A higher value makes the spring less stiff. The default is 0. | | **Spring Damping** | Sets how quickly the spring stops pulling or pushing. A higher value makes the spring settle more quickly. The default is 0. | | **Spring Lower Force** | Sets the maximum force that the spring applies when it's stretched, in newtons. | | **Spring Upper Force** | Sets the maximum force that the spring applies when it's compressed, in newtons. | ### Motor | **Property** | **Description** | | ------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Enable Motor** | Makes the constraint act as a winch to pull or push the two connected objects. If you disable **Enable Spring**, this property has no effect.**Note**: The motor can drive the objects beyond the **Distance** value if it overpowers the spring. | | **Motor Speed** | Sets the target motor speed, in meters per second. | | **Max Motor Force** | Sets the maximum force that the motor applies to reach the target speed, in newtons. | ### Limit | **Property** | **Description** | | ---------------------- | --------------------------------------------------------------------------------------------------------------------- | | **Enable Limit** | Limits the distance between the two connected objects. If you disable **Enable Spring**, this property has no effect. | | **Min Distance Limit** | Sets the minimum distance between the objects in meters. | | **Max Distance Limit** | Sets the maximum distance between the objects in meters. | ### Thresholds | **Property** | **Description** | | -------------------- | ------------------------------------------------------------------------------- | | **Force Threshold** | Sets the amount of linear force that creates an `OnJointThreshold2D` event. | | **Torque Threshold** | Sets the amount of rotational force that creates an `OnJointThreshold2D` event. | ### Tuning | **Property** | **Description** | | -------------------- | -------------------------------------------------------------------------------------------------------------------------- | | **Tuning Frequency** | Sets the overall stiffness of the constraint in Hertz (cycles per second). A higher value makes the constraint less stiff. | | **Tuning Damping** | Sets how quickly overall the constraint stops pulling or pushing. A higher value makes the constraint settle more quickly. | ### Drawing | **Property** | **Description** | | ----------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Draw Scale** | Scales the constraint Unity draws as a debug visualization. For more information, refer to [Visualize and edit 2D Physics Core scenes](/engine/6000.7/manual/unity2d/2d-physics-api/create-objects/debug-drawing.md). | | **World Drawing** | Draws the constraint when Unity draws the debug visualization of the world. For more information, refer to [Visualize and edit 2D Physics Core scenes](/engine/6000.7/manual/unity2d/2d-physics-api/create-objects/debug-drawing.md). | ## Callbacks | **Property** | **Description** | | ------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Callback Source** | Sets the callback method the constraint calls when the force or torque exceeds **Force Threshold** or **Torque Threshold**. The options are:**Off**: Calls no callbacks.**Constraint**: Calls the [`PhysicsConstraintCallbacks.IJointThresholdCallback`](https://docs.unity3d.com/Packages/com.unity.2d.physics@latest?subfolder=/api/Unity.U2D.Physics.PhysicsConstraintCallbacks.IJointThresholdCallback.html) method on the **Callback Target** object, passing this component.**Joints**: Calls the [`PhysicsCallbacks.IJointThresholdCallback`](/engine/6000.7/script-reference/unity/u2d/physics/physicscallbacks/ijointthresholdcallback.md.md) method on the **Callback Target** object, passing the `Joint` object.**Events**: Calls a method or sets a parameter you select in the **On Joint Threshold (JointThresholdEvent)** section. | | **Callback Target** | Sets the object that receives physics callbacks. This property is available only if you set **Callback Source** to **Constraint** or **Joints**. | ### Event settings The properties in this section set the specific method this constraint calls or the parameter it sets, and control the behavior of the `On Joint Threshold (JointThresholdEvent)` method of the component. This section is available only if you set **Callback Source** to **Events**. | **Property** | **Description** | | ------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Activation** | Sets when the constraint activates the callback method or sets the parameter. The options are:**Off**: Doesn't activate the callback method or set the parameter.**Editor and Runtime**: Activates the callback method or sets the parameter in the Unity Editor and at runtime.**Runtime Only**: Activates the callback method or sets the parameter only at runtime. | | **Object** | Sets the object with the method to call or parameter to update. 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](/engine/6000.7/manual/unity2d/2d-physics-api/properties/custom-data.md.md). | **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](/engine/6000.7/manual/unity2d/2d-physics-api/interactions/collisions-enable.md.md). | | **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 constraint. 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** | | ------------------- | ------------------------------------------------------------------- | | **Joint Threshold** | How many times a joint callback was dispatched to a valid receiver. | ### Other properties | **Property** | **Description** | | --------------------- | ----------------------------------------------------------------- | | **Constraint Force** | The current force the constraint applies, as a vector in newtons. | | **Constraint Torque** | The current torque the constraint applies, in newton-meters. | ## Additional resources * [Add a constraint](/engine/6000.7/manual/unity2d/2d-physics-api/connect-objects/create-constraint.md) * [Introduction to constraints](/engine/6000.7/manual/unity2d/2d-physics-api/connect-objects/joints.md) * [Share properties across multiple 2D Physics Core components](/engine/6000.7/manual/unity2d/2d-physics-api/properties/definitions.md) * [Visualize and edit 2D Physics Core scenes](/engine/6000.7/manual/unity2d/2d-physics-api/create-objects/debug-drawing.md) * [Collisions and interactions in 2D Physics Core](/engine/6000.7/manual/unity2d/2d-physics-api/interactions.md)