Unreal Engine 5 Documentation has been moved to the Epic Developer Community

Unreal Engine 4.26

Unreal Engine 4.27

Unreal Engine 5.0

Unreal Engine 5.1

Unreal Engine 5.2

Unreal Engine 5.3

> Making Interactive Experiences > Physics > Physics Constraints > Physics Constraint Reference

Light Theme

Dark Theme

Physics Constraint Reference

A reference for all the properties available on Physics Constraints in Unreal Editor.

Choose your operating system:

Windows

macOS

Linux

On this page

Constraint
Constraint Behavior
Linear Limits
- Advanced
Angular Limits
- Advanced
Linear Motor
- Advanced
Angular Motor
- Advanced

This page contains a reference listing of properties for Physics Constraints separated by major category.

Constraint


Property	Description
Constraint Actor 1	When a Physics Constraint is placed into the level editor you must specify Actors to constrain. This is the first of 2 Actors .
Component Name 1	The first target component that will be constrained. This can be specified when using Actors to constrain only a specific component and not the Actor root.
Constraint Actor 2	When a Physics Constraint is placed into the level editor you must specify Actors to constrain. This is the second of 2 Actors .
Component Name 2	The second target component that will be constrained. This can be specified when using Actors to constrain only a specific component and not the Actor root.
Joint Name	When constraining in the Physics Asset Tool , this is the name of the Bone that is initially constrained.
Constraint Bone 1	When constraining in the Physics Asset Tool , this is the name of the first joint to constrain.
Constraint Bone 2	When constraining in the Physics Asset Tool , this is the name of the second joint to constrain.

Constraint Behavior


Property	Description
Disable Collision	This disables collision between the constrained components.
Enable Projection	If the distance error between bodies exceeds Projection Linear Tolerance value, or rotational error exceeds Projection Angular Tolerance , the Physics Body will be projected to fix this. This fixes cases where the visuals look disconnected, such as individual chain links breaking away from each other.
Projection Linear Tolerance	If the distance error exceeds this value, in world units, the body will be projected.
Projection Angular Tolerance	If the rotational error exceeds this value, in degrees, the body will be projected.
Parent Dominates	When set, the parent body in a constraint will not be affected by the motion of the child.

Linear Limits

Property

Description

XMotion

Indicates the linear constraint applied along the X-axis.


Type	Description
Free	No constraint along this axis
Limited	Limited freedom along this axis. The limit is defined for all axes by the Linear Limit Size property.
Locked	Fully constraint along this axis.

YMotion

Indicates the linear constraint applied along the Y-axis.


Type	Description
Free	No constraint along this axis
Limited	Limited freedom along this axis. The limit is defined for all axes by the Linear Limit Size property.
Locked	Fully constraint along this axis.

ZMotion

Indicates the linear constraint applied along the Z-axis.


Type	Description
Free	No constraint along this axis
Limited	Limited freedom along this axis. The limit is defined for all axes by the Linear Limit Size property.
Locked	Fully constraint along this axis.

Limit

The distance allowed between the two joint reference frames.

Scale Linear Limits

If true, linear limits scale using the absolute min of the 3D scale of the owning component.

Advanced


Property	Description
Soft Constraint	Whether we want to use a soft constraint (spring).
Stiffness	Stiffness of the soft constraint. Only used when Soft Constraint is on.
Damping	Damping of the soft constraint.
Restitution	Controls the amount of bounce when the constraint is violated.
Contact Distance	Determines how close to the limit we have to get before turning the joint on.
Linear Breakable	Whether it is possible to break the joint with linear force.
Linear Break Threshold	Force needed to break the distance constraint.

Angular Limits

Property

Description

Swing 1Motion

Indicates whether the Swing1 limit is used.


Type	Description
Free	No constraint around the axis
Limited	Limited freedom around this axis. The limit for each Angular Motion is controlled individually by a correspondingly named Limit property: Swing 1Limit Angle, Swing 2Limit Angle, and Twist Limit Angle
Locked	Fully constraint around this axis

Swing 2Motion

Indicates whether the Swing2 limit is used.


Type	Description
Free	No constraint around the axis
Limited	Limited freedom around this axis. The limit for each Angular Motion is controlled individually by a correspondingly named Limit property: Swing 1Limit Angle, Swing 2Limit Angle, and Twist Limit Angle
Locked	Fully constraint around this axis

Twist Motion

Indicates whether the Twist limit is used.


Type	Description
Free	No constraint around the axis
Limited	Limited freedom around this axis. The limit for each Angular Motion is controlled individually by a correspondingly named Limit property: Swing 1Limit Angle, Swing 2Limit Angle, and Twist Limit Angle
Locked	Fully constraint around this axis

Swing 1Limit Angle

Angle of movement along the XY Plane.

Twist Limit Angle

Angle of movement along the XZ Plane.

Swing 2Limit Angle

Symmetric angle of roll along the X-axis.

Advanced


Property	Description
Swing Limits
Soft Constraint	Whether we want to use a soft constraint (spring).
Stiffness	Stiffness of the soft constraint. Only used when Soft Constraint is on.
Damping	Damping of the soft constraint.
Restitution	Controls the amount of bounce when the constraint is violated.
Contact Distance	Determines how close to the limit we have to get before turning the joint on.
Twist Limits
Soft Constraint	Whether we want to use a soft constraint (spring).
Stiffness	Stiffness of the soft constraint. Only used when Soft Constraint is on.
Damping	Damping of the soft constraint.
Restitution	Controls the amount of bounce when the constraint is violated.
Contact Distance	Determines how close to the limit we have to get before turning the joint on.
Breakable
Angular Breakable	Whether it is possible to break the joint with angular force.
Angular Break Threshold	Torque needed to break the joint.

Linear Motor


Property	Description
Position Target	Enables the position linear motor on one or more axes and sets the local position desired.
Strength	How much force to apply to reach the desired position.
Velocity Target	Enables the velocity linear motor on one or more axes and sets the desired velocity.
Strength	How much force to apply to reach the desired velocity.

Advanced


Property	Description
Max Force	The force limit of the drive.

Angular Motor

Property

Description

Angular Drive Mode

Whether this angular motor uses SLERP (Spherical Linear Interpolation) or decompose into a Swing Motor and a Twist Motor (cone and roll constraints). SLERP will not work if any of the angular constraints are locked.


Property	Description
SLERP	Sets the motor to SLERP (Spherical Linear Interpolation) mode. SLERP mode will not work if any of axis of the angular constraint is locked.
Twist and Swing	Sets the motor to Twist and Swing (cone and roll constraints) mode.

Target Orientation

Target proemtatopm relative to the body reference frame.

Drives

Depending on the Angular Drive Mode setting, you can enable or disable the different motors for that mode.

Strength

The force applied to reach the target orientation.

Target Velocity

Target angular velocity relative to the body reference frame

Drives

Depending on the Angular Drive Mode setting, you can enable or disable the different motors for that mode.

Stength

The force applied to reach the target velocity.

Advanced


Property	Description
Max Force	The force limit of the drive.