Physics components — colliders, Rigidbody, and joints

s&box uses a component-based physics system built on Jolt Physics. This page covers the full API for all collider types, the Rigidbody component, and the joint components that constrain bodies to each other.

Colliders

Colliders define the shape of an object for physics simulation. They can exist standalone (acting as static or kinematic bodies) or alongside a Rigidbody (which controls dynamic simulation). All colliders share a common base class, Collider.

Collider base properties

All collider types inherit these properties from Collider.

Static

bool

default:"false"

When true, the collider is fixed in the world and never moves. When false and not attached to a Rigidbody, the collider is kinematic — it follows GameObject transform changes but is not driven by physics forces.

IsDynamic

bool

Read-only. true only when the collider is simulated by a Rigidbody with MotionEnabled. Returns false for static and kinematic bodies.

IsTrigger

bool

default:"false"

When true, the collider becomes a trigger volume. It detects overlaps but does not generate contact forces. Triggers fire OnTriggerEnter and OnTriggerExit.

Touching

IEnumerable<Collider>

Read-only. When this is a trigger, lists all colliders currently overlapping it. When this is a regular collider, lists all triggers it is currently touching.

LocalBounds

BBox

Read-only. The local bounding box encompassing all physics shapes in this collider.

Surface properties

Friction

float?

Overrides the material friction for this collider. Accepts values above 1 for extra grip. Leave as null to use the surface asset’s value.

Elasticity

float?

Controls how bouncy the collider is. 0 is fully inelastic; 1 is fully elastic. Leave as null to use the surface asset’s value.

RollingResistance

float?

Reduces rolling speed for sphere and capsule shapes. Leave as null to use the surface asset’s value.

Surface

The surface asset that defines sound, footstep, and material properties. Individual Friction, Elasticity, and RollingResistance overrides take priority over the asset’s values.

SurfaceVelocity

Vector3

A local velocity applied to the surface of the collider. Objects resting on this collider slide in this direction — useful for conveyor belts.

Trigger events

OnTriggerEnter

Action<Collider>

Fired when another collider enters this trigger volume.

OnTriggerExit

Action<Collider>

Fired when another collider exits this trigger volume.

OnObjectTriggerEnter

Action<GameObject>

Fired with the entering GameObject when any of its colliders enters this trigger.

OnObjectTriggerExit

Action<GameObject>

Fired with the exiting GameObject when all of its colliders have left this trigger.

Collider methods

GetVelocityAtPoint( Vector3 worldPoint )

Vector3

Returns the velocity of this collider at the given world-space point, accounting for rotation.

FindClosestPoint( Vector3 worldPoint )

Vector3

Returns the closest point on any convex shape of this collider to the given world-space point.

GetWorldBounds()

BBox

Returns the world-space bounding box of all physics shapes attached to this collider.

BoxCollider

BoxCollider defines a rectangular box shape.

var box = go.Components.Create<BoxCollider>();
box.Scale = new Vector3( 100, 100, 100 );
box.Center = Vector3.Zero;

Scale

Vector3

default:"(50, 50, 50)"

The full extents of the box from corner to corner in local space.

Center

Vector3

default:"(0, 0, 0)"

The center of the box relative to the GameObject’s local origin.

SphereCollider

SphereCollider defines a sphere shape. When the GameObject has non-uniform scale, the shape degrades to a convex hull approximation.

var sphere = go.Components.Create<SphereCollider>();
sphere.Radius = 32;
sphere.Center = Vector3.Zero;

Radius

float

default:"32"

Radius of the sphere in local space.

Center

Vector3

default:"(0, 0, 0)"

Center of the sphere relative to the GameObject’s local origin.

CapsuleCollider

CapsuleCollider defines a pill-shaped capsule between two points.

var capsule = go.Components.Create<CapsuleCollider>();
capsule.Start = Vector3.Zero;
capsule.End = Vector3.Up * 60;
capsule.Radius = 16;

Start

Vector3

default:"(0, 0, 0)"

Bottom center point of the capsule in local space.

End

Vector3

default:"(0, 0, 10)"

Top center point of the capsule in local space.

Radius

float

default:"16"

Radius of the capsule’s circular cross-section.

ModelCollider

ModelCollider generates physics shapes from a Model asset’s embedded collision data.

var mc = go.Components.Create<ModelCollider>();
mc.Model = Model.Load( "models/crate.vmdl" );

Model

The model whose physics parts are used to build shapes. If left unset, ModelCollider attempts to auto-detect a sibling ModelRenderer and use its model.

ModelCollider supports concave meshes (IsConcave returns true for mesh parts). Concave colliders are always static — you cannot attach them to a Rigidbody with MotionEnabled.

Rigidbody

Rigidbody adds dynamic physics simulation to a GameObject. It requires at least one collider on the same object or a child object to generate the body’s mass and contact shapes.

var rb = go.Components.Create<Rigidbody>();
rb.Gravity = true;
rb.LinearDamping = 0.1f;

Rigidbody properties

Gravity

bool

default:"true"

Enables or disables gravitational force on this body.

GravityScale

float

default:"1.0"

Multiplier applied to PhysicsWorld.Gravity. Use 2 for double gravity, 0 to neutralize gravity without disabling it.

LinearDamping

float

default:"0"

Linear drag applied every physics step. Higher values slow linear movement faster.

AngularDamping

float

default:"0"

Angular drag applied every physics step. Higher values slow rotation faster.

MassOverride

float

default:"0"

Sets the body’s mass when greater than zero. When zero, mass is automatically computed from attached collider shapes and their surface densities.

Mass

float

Read-only. The current computed or overridden mass of the body in kilograms.

MassCenter

Vector3

Read-only. The center of mass in local space.

OverrideMassCenter

bool

default:"false"

When true, uses MassCenterOverride instead of the automatically computed center of mass.

MassCenterOverride

Vector3

Custom center of mass in local space. Only active when OverrideMassCenter is true.

Velocity

Vector3

Current linear velocity. Read or write to get or set the body’s movement. On proxies (networked), returns the last synced value.

AngularVelocity

Vector3

Current angular velocity in radians per second.

MotionEnabled

bool

default:"true"

When false, the body becomes kinematic — it still generates contacts but is not moved by forces.

Sleeping

bool

true when the physics engine has put the body to sleep due to low velocity. You can set this to false to wake it.

StartAsleep

bool

default:"false"

When true, the body starts in the sleep state on spawn.

Locking

PhysicsLock

Flags that restrict movement on specific axes. Combine flags to lock, for example, PhysicsLock.PositionZ | PhysicsLock.RotationX.

RigidbodyFlags

Miscellaneous flags. Currently supports DisableCollisionSounds to suppress automatic impact sound effects.

EnhancedCcd

bool

default:"false"

Enables continuous collision detection against dynamic bodies. Use for fast-moving objects like bullets.

PreciseContacts

bool

default:"false"

Forces contact manifolds to be freshly computed each frame instead of being recycled. Reduces ghost collisions on character-like bodies.

SleepThreshold

float

default:"2.0"

Speed in units per second below which the body enters sleep. Increase to improve stacking stability.

CollisionEventsEnabled

bool

default:"true"

When false, disables ICollisionListener events and collision sound triggers for this body.

CollisionUpdateEventsEnabled

bool

default:"false"

When true, OnCollisionUpdate is also dispatched while a collision persists each frame.

PhysicsBody

Read-only. The underlying PhysicsBody handle. May be null when the component is disabled. Do not store — the body can be recreated.

Touching

IEnumerable<Collider>

Read-only. All trigger colliders currently touching this rigidbody.

Joints

IReadOnlySet<Joint>

Read-only. All joints currently connected to this body.

Rigidbody methods

ApplyForce( in Vector3 force )

void

Applies a continuous force to the body at the center of mass. Force is accumulated and applied during the next physics step.

ApplyForceAt( in Vector3 position, in Vector3 force )

void

Applies a continuous force at a specific world-space point, generating torque when off-center.

ApplyTorque( in Vector3 force )

void

Applies angular force (torque) to the body.

ApplyImpulse( in Vector3 force )

void

Applies an instantaneous velocity change (impulse) at the center of mass.

ApplyImpulseAt( in Vector3 position, in Vector3 force )

void

Applies an instantaneous impulse at a specific world-space point.

ClearForces()

void

Cancels any accumulated forces that have not yet been applied to the body this frame.

SmoothMove( in Transform transform, float timeToArrive, float timeDelta )

void

Moves the body toward transform using velocity rather than teleportation, cooperating with the physics solver. Good for grabbed objects.

SmoothMove( in Vector3 position, float timeToArrive, float timeDelta )

void

Position-only overload of SmoothMove.

SmoothRotate( in Rotation rotation, float timeToArrive, float timeDelta )

void

Rotates the body toward rotation using angular velocity, cooperating with the solver.

GetVelocityAtPoint( in Vector3 position )

Vector3

Returns the world-space velocity at a specific point on the body, including the contribution of angular velocity.

FindClosestPoint( in Vector3 position )

Vector3

Returns the closest point on any convex shape of this body to the given world-space position.

GetWorldBounds()

BBox

Returns the world-space bounding box of the physics body.

InertiaTensor

Vector3

Gets or sets the inertia tensor diagonal. Set to override the auto-computed value; call ResetInertiaTensor() to revert.

ResetInertiaTensor()

void

Reverts InertiaTensor and InertiaTensorRotation to the values automatically computed from attached colliders.

Joints

Joints constrain two physics bodies relative to each other. All joints share a common Joint base class. Place a joint component on any GameObject and set the Body property to the target. The joint itself anchors at the component’s GameObject by default.

Joint base properties

Body

GameObject

The GameObject whose physics body this joint constrains. The joint searches the GameObject hierarchy upward for a Rigidbody or Collider. If none is found, the joint anchors to the world body.

AnchorBody

GameObject

Optional override for the source body. Defaults to the GameObject the joint component is on.

EnableCollision

bool

default:"false"

When true, the two connected bodies can still collide with each other.

BreakForce

float

default:"0"

Maximum linear impulse the joint can sustain before breaking. 0 means indestructible.

BreakTorque

float

default:"0"

Maximum angular impulse the joint can sustain before breaking. 0 means indestructible.

IsBroken

bool

Read-only at runtime. true when the joint has been broken.

OnBreak

Action

Fired when the joint breaks (either from exceeding BreakForce/BreakTorque or by calling Break()).

LinearStress

float

Read-only. The current linear impulse being applied to the joint this step.

AngularStress

float

Read-only. The current angular impulse being applied to the joint this step.

Body1

PhysicsBody

Read-only. The source physics body (the anchor side).

Body2

PhysicsBody

Read-only. The target physics body.

Joint methods

Break()

void

Breaks the joint immediately, firing OnBreak. Has no effect in the editor.

Unbreak()

void

Re-creates a previously broken joint. Has no effect in the editor.

FixedJoint

FixedJoint welds two bodies together at a fixed relative offset. The constraint is soft — it uses spring-damper parameters rather than a rigid weld, which improves solver stability.

var joint = go.Components.Create<FixedJoint>();
joint.Body = otherObject;
joint.LinearFrequency = 10;
joint.LinearDamping = 1;

LinearFrequency

float

default:"10"

Spring frequency for the linear constraint. Higher values make the weld stiffer.

LinearDamping

float

default:"1"

Damping ratio for the linear constraint. 1 is critically damped.

AngularFrequency

float

default:"10"

Spring frequency for the angular constraint.

AngularDamping

float

default:"1"

Damping ratio for the angular constraint.

HingeJoint

HingeJoint allows rotation around a single axis — like a door hinge or wheel axle. Optionally includes angle limits and a motor.

var hinge = go.Components.Create<HingeJoint>();
hinge.Body = doorBody;
hinge.MinAngle = -90;
hinge.MaxAngle = 0;

MinAngle

float

default:"0"

Minimum rotation angle in degrees.

MaxAngle

float

default:"0"

Maximum rotation angle in degrees. When both limits are 0, the hinge has unlimited rotation.

Motor

HingeJoint.MotorMode

default:"Disabled"

Motor mode. Disabled applies only friction. TargetAngle drives toward a set angle with a spring. TargetVelocity spins at a constant rate with a torque limit.

Friction

float

default:"0"

Passive resistance applied when Motor is Disabled.

TargetAngle

float

Target angle in degrees for TargetAngle motor mode.

Frequency

float

default:"1.0"

Spring frequency for the angle motor.

DampingRatio

float

default:"1.0"

Damping ratio for the angle motor.

TargetVelocity

float

Target angular velocity in degrees per second for TargetVelocity motor mode.

MaxTorque

float

Maximum torque the velocity motor can apply.

Angle

float

Read-only. Current hinge angle in degrees.

Speed

float

Read-only. Current rotational speed in degrees per second.

Axis

Vector3

Read-only. The hinge axis in world space.

SpringJoint

SpringJoint tries to maintain a target distance between two bodies using spring forces. It can pull, push, or both.

var spring = go.Components.Create<SpringJoint>();
spring.Body = target;
spring.RestLength = 100;
spring.Frequency = 5;
spring.Damping = 0.7f;

RestLength

float

default:"50"

The distance the spring tries to maintain between the two anchor points.

MinLength

float

default:"0"

Minimum allowed distance. The spring never compresses below this.

MaxLength

float

default:"100"

Maximum allowed distance. The spring never stretches beyond this.

Frequency

float

default:"5"

Spring stiffness. Higher values make the spring snap back faster.

Damping

float

default:"0.7"

Damping ratio. 1 is critically damped; values below 1 allow oscillation.

ForceMode

SpringJoint.SpringForceMode

default:"Both"

Pull applies force only when stretched, Push only when compressed, Both applies force in both directions.

SliderJoint

SliderJoint restricts a body to move along a single axis relative to another — like a piston or drawer.

var slider = go.Components.Create<SliderJoint>();
slider.Body = platform;
slider.MinLength = 0;
slider.MaxLength = 200;

MinLength

float

default:"0"

Minimum slide distance.

MaxLength

float

default:"0"

Maximum slide distance.

Friction

float

default:"0"

Passive resistance applied to sliding motion.

BallJoint

BallJoint (ball-and-socket) allows free rotation in all directions — like a shoulder joint. Optional swing and twist limits constrain the range of motion.

var ball = go.Components.Create<BallJoint>();
ball.Body = armObject;
ball.SwingLimitEnabled = true;
ball.SwingLimit = new Vector2( 0, 60 );

SwingLimitEnabled

bool

default:"false"

Enables angular swing limits.

SwingLimit

Vector2

default:"(0, 90)"

Minimum and maximum swing angles in degrees.

TwistLimitEnabled

bool

default:"false"

Enables angular twist limits.

TwistLimit

Vector2

default:"(-15, 15)"

Minimum and maximum twist angles in degrees.

Motor

BallJoint.MotorMode

default:"Disabled"

Disabled uses only friction. TargetRotation drives toward a target orientation. TargetVelocity spins at a target angular velocity.

Friction

float

default:"0.5"

Passive friction when the motor is disabled.

Physics guide

Overview of the physics system, collision layers, and best practices.

Character controller

Kinematic character movement without a Rigidbody.

Scene & GameObjects

How objects and components are organized in a scene.

Networking overview

Syncing physics bodies across clients.

Scene & Objects

Built-in Components

Systems

Physics components — colliders, Rigidbody, and joints

Colliders

Collider base properties

Surface properties

Trigger events

Collider methods

BoxCollider

SphereCollider

CapsuleCollider

ModelCollider

Rigidbody

Rigidbody properties

Rigidbody methods

Joints

Joint base properties

Joint methods

FixedJoint

HingeJoint

SpringJoint

SliderJoint

BallJoint

Physics guide

Character controller

Scene & GameObjects

Networking overview

Build docs developers (and LLMs) love

Scene & Objects

Built-in Components

Systems

Documentation Index

​Colliders

​Collider base properties

​Surface properties

​Trigger events

​Collider methods

​BoxCollider

​SphereCollider

​CapsuleCollider

​ModelCollider

​Rigidbody

​Rigidbody properties

​Rigidbody methods

​Joints

​Joint base properties

​Joint methods

​FixedJoint

​HingeJoint

​SpringJoint

​SliderJoint

​BallJoint

​Related pages

Physics guide

Character controller

Scene & GameObjects

Networking overview

Build docs developers (and LLMs) love

Colliders

Collider base properties

Surface properties

Trigger events

Collider methods

BoxCollider

SphereCollider

CapsuleCollider

ModelCollider

Rigidbody

Rigidbody properties

Rigidbody methods

Joints

Joint base properties

Joint methods

FixedJoint

HingeJoint

SpringJoint

SliderJoint

BallJoint

Related pages