Module org.dyn4j

Class RopeJoint<T extends PhysicsBody>

  • Type Parameters:
    T - the PhysicsBody type
    All Implemented Interfaces:
    DataContainer, Shiftable, Ownable

    public class RopeJoint<T extends PhysicsBody>
    extends Joint<T>
    implements Shiftable, DataContainer
    Implementation a maximum and/or minimum length distance joint.

    A rope joint contains the distance between two bodies. The bodies can rotate freely about the anchor points. The system as a whole can rotate and translate freely as well.

    This joint is like the DistanceJoint, but includes an upper and lower limit and does not include a spring-damper system.

    By default the lower and upper limits are set to the current distance between the given anchor points and will function identically like a DistanceJoint. The upper and lower limits can be enabled separately.

    The lower limit constraint requires that the bodies are initially separated for it to be enforced. The lower limit will be enforced as soon as the bodies separate, but it's recommended that they start separated instead. If the lower limit is not being used, then the initial state doesn't matter.

    Since:
    2.2.1
    Version:
    4.0.0
    Author:
    William Bittle
    See Also:
    Documentation, Distance Constraint, Max Distance Constraint
    • Constructor Detail

      • RopeJoint

        public RopeJoint​(T body1,
                         T body2,
                         Vector2 anchor1,
                         Vector2 anchor2)
        Minimal constructor.

        Creates a rope joint between the two bodies that acts like a distance joint.

        Parameters:
        body1 - the first PhysicsBody
        body2 - the second PhysicsBody
        anchor1 - in world coordinates
        anchor2 - in world coordinates
        Throws:
        NullPointerException - if body1, body2, anchor1, or anchor2 is null
        IllegalArgumentException - if body1 == body2
    • Method Detail

      • initializeConstraints

        public void initializeConstraints​(TimeStep step,
                                          Settings settings)
        Description copied from class: Joint
        Performs any initialization of the velocity and position constraints.
        Specified by:
        initializeConstraints in class Joint<T extends PhysicsBody>
        Parameters:
        step - the time step information
        settings - the current world settings
      • solveVelocityConstraints

        public void solveVelocityConstraints​(TimeStep step,
                                             Settings settings)
        Description copied from class: Joint
        Solves the velocity constraints.
        Specified by:
        solveVelocityConstraints in class Joint<T extends PhysicsBody>
        Parameters:
        step - the time step information
        settings - the current world settings
      • solvePositionConstraints

        public boolean solvePositionConstraints​(TimeStep step,
                                                Settings settings)
        Description copied from class: Joint
        Solves the position constraints.
        Specified by:
        solvePositionConstraints in class Joint<T extends PhysicsBody>
        Parameters:
        step - the time step information
        settings - the current world settings
        Returns:
        boolean true if the position constraints were solved
      • getReactionForce

        public Vector2 getReactionForce​(double invdt)
        Description copied from class: Joint
        Returns the force applied to the PhysicsBodys in order to satisfy the constraint in newtons.
        Specified by:
        getReactionForce in class Joint<T extends PhysicsBody>
        Parameters:
        invdt - the inverse delta time
        Returns:
        Vector2
      • getReactionTorque

        public double getReactionTorque​(double invdt)
        Returns the torque applied to the PhysicsBodys in order to satisfy the constraint in newton-meters.

        Not applicable to this joint. Always returns zero.

        Specified by:
        getReactionTorque in class Joint<T extends PhysicsBody>
        Parameters:
        invdt - the inverse delta time
        Returns:
        double
      • shift

        public void shift​(Vector2 shift)
        Description copied from interface: Shiftable
        Translates the object to match the given coordinate shift.
        Specified by:
        shift in interface Shiftable
        Parameters:
        shift - the amount to shift along the x and y axes
      • getUpperLimit

        public double getUpperLimit()
        Returns the upper limit in meters.
        Returns:
        double
      • setUpperLimit

        public void setUpperLimit​(double upperLimit)
        Sets the upper limit in meters.
        Parameters:
        upperLimit - the upper limit in meters; must be greater than or equal to zero
        Throws:
        IllegalArgumentException - if upperLimit is less than zero or less than the current lower limit
      • setUpperLimitEnabled

        public void setUpperLimitEnabled​(boolean flag)
        Sets whether the upper limit is enabled.
        Parameters:
        flag - true if the upper limit should be enabled
      • isUpperLimitEnabled

        public boolean isUpperLimitEnabled()
        Returns true if the upper limit is enabled.
        Returns:
        boolean true if the upper limit is enabled
      • getLowerLimit

        public double getLowerLimit()
        Returns the lower limit in meters.
        Returns:
        double
      • setLowerLimit

        public void setLowerLimit​(double lowerLimit)
        Sets the lower limit in meters.
        Parameters:
        lowerLimit - the lower limit in meters; must be greater than or equal to zero
        Throws:
        IllegalArgumentException - if lowerLimit is less than zero or greater than the current upper limit
      • setLowerLimitEnabled

        public void setLowerLimitEnabled​(boolean flag)
        Sets whether the lower limit is enabled.
        Parameters:
        flag - true if the lower limit should be enabled
      • isLowerLimitEnabled

        public boolean isLowerLimitEnabled()
        Returns true if the lower limit is enabled.
        Returns:
        boolean true if the lower limit is enabled
      • setLimits

        public void setLimits​(double lowerLimit,
                              double upperLimit)
        Sets both the lower and upper limits.
        Parameters:
        lowerLimit - the lower limit in meters; must be greater than or equal to zero
        upperLimit - the upper limit in meters; must be greater than or equal to zero
        Throws:
        IllegalArgumentException - if lowerLimit is less than zero, upperLimit is less than zero, or lowerLimit is greater than upperLimit
      • setLimitsEnabled

        public void setLimitsEnabled​(double lowerLimit,
                                     double upperLimit)
        Sets both the lower and upper limits and enables both.
        Parameters:
        lowerLimit - the lower limit in meters; must be greater than or equal to zero
        upperLimit - the upper limit in meters; must be greater than or equal to zero
        Throws:
        IllegalArgumentException - if lowerLimit is less than zero, upperLimit is less than zero, or lowerLimit is greater than upperLimit
      • setLimitsEnabled

        public void setLimitsEnabled​(boolean flag)
        Enables or disables both the lower and upper limits.
        Parameters:
        flag - true if both limits should be enabled
        Since:
        2.2.2
      • setLimits

        public void setLimits​(double limit)
        Sets both the lower and upper limits to the given limit.

        This makes the joint a fixed length joint.

        Parameters:
        limit - the desired limit
        Throws:
        IllegalArgumentException - if limit is less than zero
        Since:
        2.2.2
      • setLimitsEnabled

        public void setLimitsEnabled​(double limit)
        Sets both the lower and upper limits to the given limit and enables both.

        This makes the joint a fixed length joint.

        Parameters:
        limit - the desired limit
        Throws:
        IllegalArgumentException - if limit is less than zero
        Since:
        2.2.2
      • getLimitState

        @Deprecated
        public LimitState getLimitState()
        Deprecated.
        Deprecated in 4.0.0.
        Returns the current state of the limit.
        Returns:
        LimitState
        Since:
        3.2.0