Rigidbody

Description

Control of an object's position through physics simulation.

Adding a Rigidbody component to an object will put its motion under the control of Unity's physics engine. Even without adding any code, a Rigidbody object will be pulled downward by gravity and will react to collisions with incoming objects if the right Collider component is also present.

The Rigidbody also has a scripting API that lets you apply forces to the object and control it in a physically realistic way. For example, a car's behaviour can be specified in terms of the forces applied by the wheels. Given this information, the physics engine can handle most other aspects of the car's motion, so it will accelerate realistically and respond correctly to collisions.

In a script, the FixedUpdate function is recommended as the place to apply forces and change Rigidbody settings (as opposed to Update, which is used for most other frame update tasks). The reason for this is that physics updates are carried out in measured time steps that don't coincide with the frame update. FixedUpdate is called immediately before each physics update and so any changes made there will be processed directly.

A common problem when starting out with Rigidbodies is that the game physics appears to run in "slow motion". This is actually due to the scale used for your models. The default gravity settings assume that one world unit corresponds to one metre of distance. With non-physical games, it doesn't make much difference if your models are all 100 units long but when using physics, they will be treated as very large objects. If a large scale is used for objects that are supposed to be small, they will appear to fall very slowly - the physics engine thinks they are very large objects falling over very large distances. With this in mind, be sure to keep your objects more or less at their scale in real life (so a car should be about 4 units = 4 metres, for example).

Variables

angularDrag	The angular drag of the object.
angularVelocity	The angular velocity vector of the rigidbody.
centerOfMass	The center of mass relative to the transform's origin.
collisionDetectionMode	The Rigidbody's collision detection mode.
constraints	Controls which degrees of freedom are allowed for the simulation of this Rigidbody.
detectCollisions	Should collision detection be enabled? (By default always enabled).
drag	The drag of the object.
freezeRotation	Controls whether physics will change the rotation of the object.
inertiaTensor	The diagonal inertia tensor of mass relative to the center of mass.
inertiaTensorRotation	The rotation of the inertia tensor.
interpolation	Interpolation allows you to smooth out the effect of running physics at a fixed frame rate.
isKinematic	Controls whether physics affects the rigidbody.
mass	The mass of the rigidbody.
maxAngularVelocity	The maximimum angular velocity of the rigidbody. (Default 7) range { 0, infinity }.
position	The position of the rigidbody.
rotation	The rotation of the rigdibody.
sleepAngularVelocity	The angular velocity below which objects start going to sleep. (Default 0.14) range { 0, infinity }.
sleepVelocity	The linear velocity below which objects start going to sleep. (Default 0.14) range { 0, infinity }.
solverIterationCount	Allows you to override the solver iteration count per rigidbody.
useConeFriction	Force cone friction to be used for this rigidbody.
useGravity	Controls whether gravity affects this rigidbody.
velocity	The velocity vector of the rigidbody.
worldCenterOfMass	The center of mass of the rigidbody in world space (Read Only).

Functions

AddExplosionForce	Applies a force to the rigidbody that simulates explosion effects. The explosion force will fall off linearly with distance to the rigidbody.
AddForce	Adds a force to the rigidbody. As a result the rigidbody will start moving.
AddForceAtPosition	Applies force at position. As a result this will apply a torque and force on the object.
AddRelativeForce	Adds a force to the rigidbody relative to its coordinate system.
AddRelativeTorque	Adds a torque to the rigidbody relative to the rigidbodie's own coordinate system.
AddTorque	Adds a torque to the rigidbody.
ClosestPointOnBounds	The closest point to the bounding box of the attached colliders.
GetPointVelocity	The velocity of the rigidbody at the point worldPoint in global space.
GetRelativePointVelocity	The velocity relative to the rigidbody at the point relativePoint.
IsSleeping	Is the rigidbody sleeping?
MovePosition	Moves the rigidbody to position.
MoveRotation	Rotates the rigidbody to rotation.
SetDensity	Sets the mass based on the attached colliders assuming a constant density.
Sleep	Forces a rigidbody to sleep at least one frame.
SweepTest	Tests if a rigidbody would collide with anything, if it was moved through the scene.
SweepTestAll	Like Rigidbody.SweepTest, but returns all hits.
WakeUp	Forces a rigidbody to wake up.

Messages

OnCollisionEnter	OnCollisionEnter is called when this collider/rigidbody has begun touching another rigidbody/collider.
OnCollisionExit	OnCollisionEnter is called when this collider/rigidbody has stopped touching another rigidbody/collider.
OnCollisionStay	OnCollisionStay is called once per frame for every collider/rigidbody that is touching rigidbody/collider.

Inherited members