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> Making Interactive Experiences > Physics > Physics Bodies > Physics Bodies Reference

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Physics Bodies Reference

Physics Body, or Body Instance, property reference.

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Properties
Physics
- Advanced
Collision
- Advanced
Body Setup
- Primitive Types

This page contains a reference listing of properties in the Physics and Collision categories of properties. If you are looking for reference on Collision Responses or Collision Presets please see: Collision Response Reference .

Properties

Below are the properties for Physics Bodies (Body Instances) separated by major category.

Physics


Property	Description
Mass in KG	Mass of the body in KG.
Angular Damping	'Drag' force added to reduce angular movement
Linear Damping	'Drag' force added to reduce linear movement
Enable Gravity	If object should have the force of gravity applied
Double Sided Geometry	If enabled, the physics triangle mesh will use double sided faces when doing scene queries. This is useful for planes and single sided meshes that need traces to work on both sides.
Simple Collision Physical Material	Physical material to use for simple collision on this body. Encodes information about density, friction, and so on.
Physics Type	Simulated: Object will use physics simulation. Kinematic: Object will not be affected by physics, but can interact with physically simulated bodies. Default: Object will inherit from OwnerComponent's behavior.

Advanced


Property	Description
Start Awake	If object should start awake, or if it should initially be sleeping
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
Sleep Family	The set of values used in considering when to put this body to sleep. Normal, Sensitive, Custom
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.
Inertia Tensor Scale	Per-instance scaling of inertia (larger values mean more difficulty rotating)
Max Depenetration Velocity	The maximum velocity used to depenetrate this object
Override Walkable Slope on Instance	Whether this instance of the object has its own custom walkable slope override setting.
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).
Walkable Slope Angle	Override walkable slope, applying the rules of the Walkable Slope Behavior.
Custom Sleep Threshold Multiplier	If the Sleep Family is set to Custom , multiply the natural sleep threshold by this amount. A higher number will cause the body to sleep sooner.
Stabilization Threshold Multiplier	The stabilization factor for this body if Physics stabilization is enabled. A higher number will cause more aggressive stabilization at the risk of loss of momentum at low speeds. A value of 0 will disable stabilization for this body.
Generate Wake Events	Determines whether 'wake / sleep' events should fire when this object is woken up or put to sleep by the physics simulation.

Collision


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 Complexity	Collision Trace behavior - by default, it will keep simple (convex) and complex (per-poly) separate.
Collision Responses	See the Collision Response Reference documentation for more information.

Advanced


Property	Description
Use CCD	If true Continuous Collision Detection (CCD) will be used for this component
Ignore Analytic Collisions	If true, ignore analytic collisions and treat objects as a general implicit surface.

Body Setup


Property	Description
Skip Scale from Animation	If true, scale changes from animation are ignored. This is useful for subtle scale animations like breathing where the physics collision should remain unchanged.
Primitives	Simplified collision representation of this object.
Spheres	Sphere Elements
Boxes	Box Elements
Capsules	Sphyl Elements
Convex Elements	Convex Elements
Tapered Capsules	Tapered Capsule Elements
Consider for Bounds	Determines whether this BodySetup should be considered for the bounding box of the PhysicsAsset (and hence SkeletalMeshComponent). There is a speed improvement from having less BodySetups processed each frame when updating the bounds.
Bone Name	Used in the PhysicsAsset case. Associates this Body with a Bone in a skeletal mesh.

See below for the Detail properties for each Primitive type.

Primitive Types

Spheres


Property	Description
Center	Position of the sphere's origin.
Radius	Radius of the sphere.
Rest Offset	Offset used when generating contact points. This allows you to smooth out the Minkowski sum by radius R. Useful for making objects slide smoothly on top of irregularities.
Name	User-defined name for this shape.
Contribute to Mass	Enable if this shape should contribute to the overall mass of the body it belongs to. This lets you create extra collision volumes which do not affect the mass properties of an object.
Collision Enabled	Course per-primitive collision filtering. This allows for individual primitives to be toggled in and out of sim and query collisions without changing filtering details.

Boxes


Property	Description
Center	Position of the box's origin.
Rotation	Rotation of the box, in degrees around each axis.
X Extent	Extent of the box along the x-axis.
Y Extent	Extent of the box along the y-axis.
Z Extent	Extent of the box along the z-axis.
Rest Offset	Offset used when generating contact points. This allows you to smooth out the Minkowski sum by radius R. Useful for making objects slide smoothly on top of irregularities.
Name	User-defined name for this shape.
Contribute to Mass	Enable if this shape should contribute to the overall mass of the body it belongs to. This lets you create extra collision volumes which do not affect the mass properties of an object.
Collision Enabled	Course per-primitive collision filtering. This allows for individual primitives to be toggled in and out of sim and query collisions without changing filtering details.

Capsules


Property	Description
Center	Position of the capsule's origin.
Rotation	Rotation of the capsule, in degrees around each axis.
Radius	Radius of the capsule
Length	The length of the line-segment. Add Radius to both ends to find the total length.
Rest Offset	Offset used when generating contact points. This allows you to smooth out the Minkowski sum by radius R. Useful for making objects slide smoothly on top of irregularities.
Name	User-defined name for this shape.
Contribute to Mass	Enable if this shape should contribute to the overall mass of the body it belongs to. This lets you create extra collision volumes which do not affect the mass properties of an object.
Collision Enabled	Course per-primitive collision filtering. This allows for individual primitives to be toggled in and out of sim and query collisions without changing filtering details.

Convex Elements


Property	Description
Rest Offset	Offset used when generating contact points. This allows you to smooth out the Minkowski sum by radius R. Useful for making objects slide smoothly on top of irregularities.
Name	User-defined name for this shape.
Contribute to Mass	Enable if this shape should contribute to the overall mass of the body it belongs to. This lets you create extra collision volumes which do not affect the mass properties of an object.
Collision Enabled	Course per-primitive collision filtering. This allows for individual primitives to be toggled in and out of sim and query collisions without changing filtering details.

Tapered Capsules


Property	Description
Center	Position of the capsule's origin.
Rotation	Rotation of the capsule, in degrees around each axis.
Radius 0	Radius of the capsule start point.
Radius 1	Radius of the capsule end point.
Length	Length of the line-segment. Add Radius 0 and Radius 1 to find the total length.
Rest Offset	Offset used when generating contact points. This allows you to smooth out the Minkowski sum by radius R. Useful for making objects slide smoothly on top of irregularities.
Name	User-defined name for this shape.
Contribute to Mass	Enable if this shape should contribute to the overall mass of the body it belongs to. This lets you create extra collision volumes which do not affect the mass properties of an object.
Collision Enabled	Course per-primitive collision filtering. This allows for individual primitives to be toggled in and out of sim and query collisions without changing filtering details.

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