CCPhysicsJoint Class Reference

Inherits from	NSObject
Declared in	CCPhysicsJoint.h

Overview

CCPhysicsJoints hold two CCPhysicsBodies together in some way like a joint between bones or a hinge on a door. Joints work in a fairly automatic fashion. They are active from the moment they are created. When you are done with a joint you invalidate it in order to disable it. Joints cannot be reactivated once they are invalidated.

Tasks

Creating a CCPhysicsJoint Object

+ connectedPivotJointWithBodyA:bodyB:anchorA:
+ connectedDistanceJointWithBodyA:bodyB:anchorA:anchorB:
+ connectedDistanceJointWithBodyA:bodyB:anchorA:anchorB:minDistance:maxDistance:
+ connectedSpringJointWithBodyA:bodyB:anchorA:anchorB:restLength:stiffness:damping:
+ connectedRotarySpringJointWithBodyA:bodyB:restAngle:stifness:damping:
+ connectedMotorJointWithBodyA:bodyB:rate:
+ connectedRotaryLimitJointWithBodyA:bodyB:min:max:
+ connectedRatchetJointWithBodyA:bodyB:phase:ratchet:

Accessing Physics Joint Attributes

bodyA property
bodyB property
maxForce property
collideBodies property
impulse property
breakingForce property
valid property
– invalidate

Properties

bodyA

The first body this joint is attached to.

@property (nonatomic, readonly) CCPhysicsBody *bodyA

Declared In

CCPhysicsJoint.h

bodyB

The second body this joint is attached to.

@property (nonatomic, readonly) CCPhysicsBody *bodyB

Declared In

CCPhysicsJoint.h

breakingForce

Maximum force that can be applied before the joint disables itself. Defaults to INFINITY To avoid problems with solver accuracy, make sure that this value is lower than CCPhysicsJoint.maxForce.

@property (nonatomic, assign) CGFloat breakingForce

Declared In

CCPhysicsJoint.h

collideBodies

Whether or not the connected bodies are allowed to collide with each other. Defaults to YES.

@property (nonatomic, assign) BOOL collideBodies

Declared In

CCPhysicsJoint.h

impulse

Depending on the joint, either the magnitude of the linear or angular impulse that this joint applied on the previous fixed time step.

@property (nonatomic, readonly) CGFloat impulse

Declared In

CCPhysicsJoint.h

maxForce

Maxium foce this joint is allowed to use. Defaults to INFINITY.

@property (nonatomic, assign) CGFloat maxForce

Declared In

CCPhysicsJoint.h

valid

Check if the joint is still valid and active.

@property (nonatomic, readonly) BOOL valid

Declared In

CCPhysicsJoint.h

Class Methods

connectedDistanceJointWithBodyA:bodyB:anchorA:anchorB:

Creates and returns a pivot joint between the two bodies and keeps the distance of the two anchor points constant. The anchor points are specified in the coordinates of the node that the bodies are attached to. The distance between the anchor points will be calculated when the joint first becomes active.

+ (CCPhysicsJoint *)connectedDistanceJointWithBodyA:(CCPhysicsBody *)bodyA bodyB:(CCPhysicsBody *)bodyB anchorA:(CGPoint)anchorA anchorB:(CGPoint)anchorB

Parameters

bodyA: Body A.

bodyB: Body B.

anchorA: Anchor point A.

anchorB: Anchor point B.

Return Value

The CCPhysicsJoint Object.

Declared In

CCPhysicsJoint.h

connectedDistanceJointWithBodyA:bodyB:anchorA:anchorB:minDistance:maxDistance:

Creates and returns a pivot joint between the two bodies and keeps the distance of the two anchor points within the range. The anchor points are specified in the coordinates of the node that the bodies are attached to.

+ (CCPhysicsJoint *)connectedDistanceJointWithBodyA:(CCPhysicsBody *)bodyA bodyB:(CCPhysicsBody *)bodyB anchorA:(CGPoint)anchorA anchorB:(CGPoint)anchorB minDistance:(CGFloat)min maxDistance:(CGFloat)max

Parameters

bodyA: Body A.

bodyB: Body B.

anchorA: Anchor point A.

anchorB: Anchor point B.

min: The minimum distance to allow between the anchor points.

max: The maximum distance to allow between the anchor points.

Return Value

The CCPhysicsJoint Object.

Declared In

CCPhysicsJoint.h

connectedMotorJointWithBodyA:bodyB:rate:

Creates and returns a Motor joint between the two bodies. No anchor points are specified as this joint can be used in conjunction with a pivot joint to make a motor around a pivot point.

+ (CCPhysicsJoint *)connectedMotorJointWithBodyA:(CCPhysicsBody *)bodyA bodyB:(CCPhysicsBody *)bodyB rate:(CGFloat)rate

Parameters

bodyA: Body A.

bodyB: Body B.

rate: Rate at which the rotate relative to each other. Negative values to reverse direction.

Return Value

The CCPhysicsJoint Object.

Declared In

CCPhysicsJoint.h

connectedPivotJointWithBodyA:bodyB:anchorA:

Creates and returns a pivot joint object between the two bodies specified. The pivot point is specified in the coordinates of the node that bodyA is attached to.

+ (CCPhysicsJoint *)connectedPivotJointWithBodyA:(CCPhysicsBody *)bodyA bodyB:(CCPhysicsBody *)bodyB anchorA:(CGPoint)anchorA

Parameters

bodyA: Body A.

bodyB: Body B.

anchorA: Anchor point A.

Return Value

The CCPhysicsJoint Object.

Declared In

CCPhysicsJoint.h

connectedRatchetJointWithBodyA:bodyB:phase:ratchet:

Creates and returns ratchet jointwhereby the angle of rotation between too bodies can go forwards smoothely, but the backwards motion is clipped at ‘ratchet’ intervals. No anchor points are specified as this joint can be used in conjunction with a pivot joint to ratchet its range of motion.

+ (CCPhysicsJoint *)connectedRatchetJointWithBodyA:(CCPhysicsBody *)bodyA bodyB:(CCPhysicsBody *)bodyB phase:(CGFloat)phase ratchet:(CGFloat)ratchet

Parameters

bodyA: Body A.

bodyB: Body B.

phase: Phase angle in Radians [0, 2 PI] describing where within the rathet interval the joint is located.

ratchet: Ratchet interval angle in radians.

Return Value

The CCPhysicsJoint Object.

Declared In

CCPhysicsJoint.h

connectedRotaryLimitJointWithBodyA:bodyB:min:max:

Creates and returns joint whereby the angle of rotation between too bodies is limited. No anchor points are specified as this joint can be used in conjunction with a pivot joint to make the pivots range of motion limited.

+ (CCPhysicsJoint *)connectedRotaryLimitJointWithBodyA:(CCPhysicsBody *)bodyA bodyB:(CCPhysicsBody *)bodyB min:(CGFloat)min max:(CGFloat)max

Parameters

bodyA: Body A.

bodyB: Body B.

min: Minimum angle in radians.

max: Maximum angle in radians.

Return Value

The CCPhysicsJoint Object.

Declared In

CCPhysicsJoint.h

connectedRotarySpringJointWithBodyA:bodyB:restAngle:stifness:damping:

Creates and returns a rotary spring joint between the two bodies. No anchor points are specified as this joint can be used in conjunction with a pivot joint to make a springing pivot joint.

+ (CCPhysicsJoint *)connectedRotarySpringJointWithBodyA:(CCPhysicsBody *)bodyA bodyB:(CCPhysicsBody *)bodyB restAngle:(CGFloat)restAngle stifness:(CGFloat)stiffness damping:(CGFloat)damping

Parameters

bodyA: Body A.

bodyB: Body B.

restAngle: Rest angle.

stiffness: Spring stiffness.

damping: Sprin damping.

Return Value

The CCPhysicsJoint Object.

Declared In

CCPhysicsJoint.h

connectedSpringJointWithBodyA:bodyB:anchorA:anchorB:restLength:stiffness:damping:

Creates and returns a spring joint between the two bodies at the specified anchor points. The anchor points are specicied in the coordinates of the node that he bodies are attached to.

+ (CCPhysicsJoint *)connectedSpringJointWithBodyA:(CCPhysicsBody *)bodyA bodyB:(CCPhysicsBody *)bodyB anchorA:(CGPoint)anchorA anchorB:(CGPoint)anchorB restLength:(CGFloat)restLength stiffness:(CGFloat)stiffness damping:(CGFloat)damping

Parameters

bodyA: Body A.

bodyB: Body B.

anchorA: Anchor point A.

anchorB: Anchor point B.

restLength: Rest Length.

stiffness: Spring stiffness.

damping: Sprin damping.

Return Value

The CCPhysicsJoint Object.

Declared In

CCPhysicsJoint.h

Instance Methods

invalidate

Disable the joint and remove it from the simulation.

- (void)invalidate

Declared In

CCPhysicsJoint.h