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Physics Asset Properties Reference

This page contains a reference listing of properties for Physics Asset Tool, separated into 3 expandable sections based on what is selected in the viewport.

Physics Asset Tool Properties

When no Physics Body or Physics Constraint is selected (regardless of mode), the properties for the Physics Asset Tool are show in the Details panel.

Anim

PhATDef1.png

Property Description
Physics Blend Enables you to manually control the physics/animation blend while simulating in the Physics Asset Tool.
Update Joints from Animation Let's you manually control the physics/animation.
Physics Update Mode

Determines whether simulation of root body updates component transform.

Value Description
Simulation Updates Component Transfrom Simulation updates the component's transform.
Component Trasform is Kinematic Simulation doesn't update the component's transform. Instead it is driven by animation, blueprint, etc...
Poke Pause Time Time between poking a ragdoll and starting to blend back.
Poke Blend Time Time taken to blend from physics to animation.

Simulation

PhATDef2.png

Property Description
Floor Gap The gap between the floor and physics objects in the Physics Asset Tool. Changing this requires a restart of the Physics Asset Tool.
Grav Scale Scale factor for the gravity used in the simulation while in the Physics Asset Tool.
Max FPS Max FPS for simulation in PhAT. This is helpful for targeting the same FPS as your game. -1 means this is disabled.
Time Dilation This will dilate the time by scale.

Mouse Spring

PhATDef3.png

Property Description
Handle Linear Damping Linear damping of mouse spring forces.
Handle Linear Stiffness Linear stiffness of mouse spring forces.
Handle Angular Damping Angular damping of mouse spring forces.
Handle Angular Stiffness Angular stiffness of mouse spring forces.
Interpolation Speed How quickly we interpolate the physics target transform for mouse spring forces.

Poking

PhATDef4.png

Property Description
Poke Strength Strength of the impulse used when poking with the left mouse button.

Advanced

PhATDef5.png

Property Description
Show Constraints as Points Whether or not to draw constraints as points.
Show Names in Hierarchy Whether or not to draw bone names in the viewport.

Drawing

PhATDef6.png

Property Description
Constraint Draw Size Controls how large constraints are drawn in the Physics Asset Tool.

Body Mode Properties

When the Physics Asset Tool is in Body Mode and a Physics Body is selected, the Details panel will display the properties for that Physics Body.

Physics

PhATBody2.png

Property Description
Mass in KG Mass of the body in KG.
Linear Damping "Drag" force added to reduce linear movement.
Angular Damping "Drag" force added to reduce angular movement.
Enable Gravity If object should have the force of gravity applied.
Physics Type If this is set to Unfixed it will use physics. If this is set to Fixed it will use kinematic. Default will inherit from OwnerComponent's behavior.
Double Sided Geometry If true, the physics triangle mesh will use double sided faces when doing scene queries. Thsi is useful for planes and single sided meshes that need traces to work on both sides.
Simple Collision Physical Material The Physical Material to use for simple collision on this body.

Advanced

PhATBody2_adv.png

Property Description
Start Awake If the physics body should start awake (and moving), or asleep (stationary until interacted with).
Center of Mass Offset User specified offset for the center of mass of this object, from the calculated location.
Mass Scale Per-instance scaling of mass.
Max Angular Velocity The maximum angular velocity for this instance.
Generate Wake Events Should wake/sleep events fire when this object is woken up or put to sleep by the physics simulation.
Max Depenetration Velocity The maximum velocity used to depenetrate this object.
Walkable Slope Override Custom walkable slope setting for this body. See the Walkable Slope documentation for usage information.
Walkable Slope Behavior Behavior of this surface (whether we affect the walkable slope). Determines how the Walkable Slope Angle operates on the existing walkable angle, whether it increases or decreases it.
Walkable Slope Angle Override walkable slope, applying the rules of the Walkable Slope Behavior.
Custom Sleep Threshold Multiplier If the SleepFamily is set to custom, multiply the natural sleep threshold by this amount. A higher number will cause the body to sleep sooner.
Position Solver Iteration Count This physics body's solver iteration count for position. Increasing this will be more CPU intensive, but better stabilized.
Velocity Solver Iteration Count This physics body's solver iteration count for velocity. Increasing this will be more CPU intensive, but better stabilized.
Sleep Family The set of values used in considering when put this body to sleep.

Body Setup

PhATBody1.png

Property Description
Primitives The basic shapes that compose this Bone's collision.
Bone Name Used in the PhysicsAsset case, associates this Body with a Bone in a Skeletal Mesh.
Consider for Bounds Should this bone be used in the calculation for the bounding volume of the Skeletal Mesh.

Collision

PhATBody3.png

Property Description
Simulation Generates Hit Events Should 'Hit' events fire when this object collides during physics simulation.
Phys Material Override Allows you to override the PhysicalMaterial to use for simple collision on this body.
Collision Response See the Collision Response Reference documentation for more information.

Advanced

PhATBody3_adv.png

Property Description
Use CCD If true Continuous Collision Detection (CCD) will be used for this component.

Physical Animation

PhATBody4.png

Please see the Physics Asset Tool How-To Landing Page for more information on using Physical Animations.

Constraint Mode Properties

When the Physics Asset Tool is in Body Mode and a Physics Body is selected, the Details panel will display the properties for that Physics Body.

Constraint

PhATCon1.png

Property Description
Joint Name The name of the bone (Physics Body) this Physics Constraint is associated with.
Constraint Bone 1 Name of the first bone (Physics Body) this Physics Constraint is connecting. This will be the "child" bone in a Physics Asset.
Constraint Bone 2 Name of the second bone (Physics Body) this Physics Constraint is connecting. This will be the "parent" bone in a Physics Asset.

Linear Limits

propProjection.png

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.

Projection

propJointPresets.png

Property Description
Hinge Setup joint as hinge. A hinge joint allows motion only in one plane.
Prismatic Setup joint as prismatic. A prismatic joint allows only linear sliding movement.
Ball and Socket Setup joint as ball and socket. A Ball and Socket joint allows motion around an indefinite number of axes, which have one common center.

Angular Limits

propLinearLimits.png

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

propLinearLimitsADV.png

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.

Linear Motor

propsAngularLimits.png

Property Description
Swing 1Motion Indicates whether the Swing1 limit is used.
Type Description
Free No constraint around this 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 this 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 this 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.
Angular Rotation Offset Specifies the angular offset between the two frames of reference. By default this limit goes from (-Angle, +Angle).

Advanced

propsAngularLimitsADV.png

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.

Angular Motor

propLinearMotor.png

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

PhysCon_MotorADV.png

Property Description
Max Force The force limit of the drive.
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