# Class: RevoluteJoint A revolute joint constrains two bodies to share a common point while they are free to rotate about the point. The relative rotation about the shared point is the joint angle. You can limit the relative rotation with a joint limit that specifies a lower and upper angle. You can use a motor to drive the relative rotation about the shared point. A maximum motor torque is provided so that infinite forces are not generated. ## Extends - [`Joint`](/api/classes/Joint) ## Constructors ### new RevoluteJoint() > **new RevoluteJoint**(`def`): [`RevoluteJoint`](/api/classes/RevoluteJoint) #### Parameters • **def**: [`RevoluteJointDef`](/api/interfaces/RevoluteJointDef) #### Returns [`RevoluteJoint`](/api/classes/RevoluteJoint) #### Overrides [`Joint`](/api/classes/Joint).[`constructor`](/api/classes/Joint#constructors) ### new RevoluteJoint() > **new RevoluteJoint**(`def`, `bodyA`, `bodyB`, `anchor`?): [`RevoluteJoint`](/api/classes/RevoluteJoint) #### Parameters • **def**: [`RevoluteJointOpt`](/api/interfaces/RevoluteJointOpt) • **bodyA**: [`Body`](/api/classes/Body) • **bodyB**: [`Body`](/api/classes/Body) • **anchor?**: [`Vec2Value`](/api/interfaces/Vec2Value) #### Returns [`RevoluteJoint`](/api/classes/RevoluteJoint) #### Overrides [`Joint`](/api/classes/Joint).[`constructor`](/api/classes/Joint#constructors) ## Properties ### style > **style**: [`Style`](/api/interfaces/Style) = `{}` Styling for dev-tools. #### Inherited from [`Joint`](/api/classes/Joint).[`style`](/api/classes/Joint#style) *** ### TYPE > `static` **TYPE**: `"revolute-joint"` ## Methods ### enableLimit() > **enableLimit**(`flag`): `void` Enable/disable the joint limit. #### Parameters • **flag**: `boolean` #### Returns `void` *** ### enableMotor() > **enableMotor**(`flag`): `void` Enable/disable the joint motor. #### Parameters • **flag**: `boolean` #### Returns `void` *** ### getAnchorA() > **getAnchorA**(): [`Vec2`](/api/classes/Vec2) Get the anchor point on bodyA in world coordinates. #### Returns [`Vec2`](/api/classes/Vec2) #### Overrides [`Joint`](/api/classes/Joint).[`getAnchorA`](/api/classes/Joint#getanchora) *** ### getAnchorB() > **getAnchorB**(): [`Vec2`](/api/classes/Vec2) Get the anchor point on bodyB in world coordinates. #### Returns [`Vec2`](/api/classes/Vec2) #### Overrides [`Joint`](/api/classes/Joint).[`getAnchorB`](/api/classes/Joint#getanchorb) *** ### getBodyA() > **getBodyA**(): [`Body`](/api/classes/Body) Get the first body attached to this joint. #### Returns [`Body`](/api/classes/Body) #### Inherited from [`Joint`](/api/classes/Joint).[`getBodyA`](/api/classes/Joint#getbodya) *** ### getBodyB() > **getBodyB**(): [`Body`](/api/classes/Body) Get the second body attached to this joint. #### Returns [`Body`](/api/classes/Body) #### Inherited from [`Joint`](/api/classes/Joint).[`getBodyB`](/api/classes/Joint#getbodyb) *** ### getCollideConnected() > **getCollideConnected**(): `boolean` Get collide connected. Note: modifying the collide connect flag won't work correctly because the flag is only checked when fixture AABBs begin to overlap. #### Returns `boolean` #### Inherited from [`Joint`](/api/classes/Joint).[`getCollideConnected`](/api/classes/Joint#getcollideconnected) *** ### getJointAngle() > **getJointAngle**(): `number` Get the current joint angle in radians. #### Returns `number` *** ### getJointSpeed() > **getJointSpeed**(): `number` Get the current joint angle speed in radians per second. #### Returns `number` *** ### getLocalAnchorA() > **getLocalAnchorA**(): [`Vec2`](/api/classes/Vec2) The local anchor point relative to bodyA's origin. #### Returns [`Vec2`](/api/classes/Vec2) *** ### getLocalAnchorB() > **getLocalAnchorB**(): [`Vec2`](/api/classes/Vec2) The local anchor point relative to bodyB's origin. #### Returns [`Vec2`](/api/classes/Vec2) *** ### getLowerLimit() > **getLowerLimit**(): `number` Get the lower joint limit in radians. #### Returns `number` *** ### getMaxMotorTorque() > **getMaxMotorTorque**(): `number` #### Returns `number` *** ### getMotorSpeed() > **getMotorSpeed**(): `number` Get the motor speed in radians per second. #### Returns `number` *** ### getMotorTorque() > **getMotorTorque**(`inv_dt`): `number` Get the current motor torque given the inverse time step. Unit is N*m. #### Parameters • **inv\_dt**: `number` #### Returns `number` *** ### getNext() > **getNext**(): [`Joint`](/api/classes/Joint) Get the next joint the world joint list. #### Returns [`Joint`](/api/classes/Joint) #### Inherited from [`Joint`](/api/classes/Joint).[`getNext`](/api/classes/Joint#getnext) *** ### getReactionForce() > **getReactionForce**(`inv_dt`): [`Vec2`](/api/classes/Vec2) Get the reaction force given the inverse time step. Unit is N. #### Parameters • **inv\_dt**: `number` #### Returns [`Vec2`](/api/classes/Vec2) #### Overrides [`Joint`](/api/classes/Joint).[`getReactionForce`](/api/classes/Joint#getreactionforce) *** ### getReactionTorque() > **getReactionTorque**(`inv_dt`): `number` Get the reaction torque due to the joint limit given the inverse time step. Unit is N*m. #### Parameters • **inv\_dt**: `number` #### Returns `number` #### Overrides [`Joint`](/api/classes/Joint).[`getReactionTorque`](/api/classes/Joint#getreactiontorque) *** ### getReferenceAngle() > **getReferenceAngle**(): `number` Get the reference angle. #### Returns `number` *** ### getType() > **getType**(): `string` Get the type of the concrete joint. #### Returns `string` #### Inherited from [`Joint`](/api/classes/Joint).[`getType`](/api/classes/Joint#gettype) *** ### getUpperLimit() > **getUpperLimit**(): `number` Get the upper joint limit in radians. #### Returns `number` *** ### getUserData() > **getUserData**(): `unknown` #### Returns `unknown` #### Inherited from [`Joint`](/api/classes/Joint).[`getUserData`](/api/classes/Joint#getuserdata) *** ### initVelocityConstraints() > **initVelocityConstraints**(`step`): `void` #### Parameters • **step**: [`TimeStep`](/api/classes/TimeStep) #### Returns `void` #### Overrides [`Joint`](/api/classes/Joint).[`initVelocityConstraints`](/api/classes/Joint#initvelocityconstraints) *** ### isActive() > **isActive**(): `boolean` Short-cut function to determine if either body is inactive. #### Returns `boolean` #### Inherited from [`Joint`](/api/classes/Joint).[`isActive`](/api/classes/Joint#isactive) *** ### isLimitEnabled() > **isLimitEnabled**(): `boolean` Is the joint limit enabled? #### Returns `boolean` *** ### isMotorEnabled() > **isMotorEnabled**(): `boolean` Is the joint motor enabled? #### Returns `boolean` *** ### setLimits() > **setLimits**(`lower`, `upper`): `void` Set the joint limits in radians. #### Parameters • **lower**: `number` • **upper**: `number` #### Returns `void` *** ### setMaxMotorTorque() > **setMaxMotorTorque**(`torque`): `void` Set the maximum motor torque, usually in N-m. #### Parameters • **torque**: `number` #### Returns `void` *** ### setMotorSpeed() > **setMotorSpeed**(`speed`): `void` Set the motor speed in radians per second. #### Parameters • **speed**: `number` #### Returns `void` *** ### setUserData() > **setUserData**(`data`): `void` #### Parameters • **data**: `unknown` #### Returns `void` #### Inherited from [`Joint`](/api/classes/Joint).[`setUserData`](/api/classes/Joint#setuserdata) *** ### shiftOrigin() > **shiftOrigin**(`newOrigin`): `void` Shift the origin for any points stored in world coordinates. #### Parameters • **newOrigin**: [`Vec2Value`](/api/interfaces/Vec2Value) #### Returns `void` #### Inherited from [`Joint`](/api/classes/Joint).[`shiftOrigin`](/api/classes/Joint#shiftorigin) *** ### solvePositionConstraints() > **solvePositionConstraints**(`step`): `boolean` This returns true if the position errors are within tolerance. #### Parameters • **step**: [`TimeStep`](/api/classes/TimeStep) #### Returns `boolean` #### Overrides [`Joint`](/api/classes/Joint).[`solvePositionConstraints`](/api/classes/Joint#solvepositionconstraints) *** ### solveVelocityConstraints() > **solveVelocityConstraints**(`step`): `void` #### Parameters • **step**: [`TimeStep`](/api/classes/TimeStep) #### Returns `void` #### Overrides [`Joint`](/api/classes/Joint).[`solveVelocityConstraints`](/api/classes/Joint#solvevelocityconstraints)