text: /*
   * Copyright (c) 2011-2018, The DART development contributors
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   * The list of contributors can be found at:
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   *
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   *   without modification, are permitted provided that the following
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   *   * Redistributions of source code must retain the above copyright
   *     notice, this list of conditions and the following disclaimer.
   *   * Redistributions in binary form must reproduce the above
   *     copyright notice, this list of conditions and the following
   *     disclaimer in the documentation and/or other materials provided
   *     with the distribution.
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   *   MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   *   DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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   *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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  #ifndef DART_CONSTRAINT_BALLJOINTCONSTRAINT_HPP_
  #define DART_CONSTRAINT_BALLJOINTCONSTRAINT_HPP_
  
  #include <Eigen/Dense>
  
  #include "dart/math/MathTypes.hpp"
  #include "dart/constraint/JointConstraint.hpp"
  
  namespace dart {
  namespace constraint {
  
  /// BallJointConstraint represents ball joint constraint between a body and the
  /// world or between two bodies
  class BallJointConstraint : public JointConstraint
  {
  public:
    /// Constructor that takes one body and the joint position in the world frame
    /// \param[in] _jointPos Joint position expressed in world frame
    BallJointConstraint(dynamics::BodyNode* _body,
                        const Eigen::Vector3d& _jointPos);
  
  
    /// Constructor that takes two bodies and the joint position in the frame of
    /// _body1
    /// \param[in] _jointPos Joint position expressed in world frame
    BallJointConstraint(dynamics::BodyNode* _body1, dynamics::BodyNode* _body2,
                        const Eigen::Vector3d& _jointPos);
  
    /// Destructor
    virtual ~BallJointConstraint();
  
  protected:
    //----------------------------------------------------------------------------
    // Constraint virtual functions
    //----------------------------------------------------------------------------
  
    // Documentation inherited
    void update() override;
  
    // Documentation inherited
    void getInformation(ConstraintInfo* _lcp) override;
  
    // Documentation inherited
    void applyUnitImpulse(std::size_t _index) override;
  
    // Documentation inherited
    void getVelocityChange(double* _vel, bool _withCfm) override;
  
    // Documentation inherited
    void excite() override;
  
    // Documentation inherited
    void unexcite() override;
  
    // Documentation inherited
    void applyImpulse(double* _lambda) override;
  
    // Documentation inherited
    bool isActive() const override;
  
    // Documentation inherited
    dynamics::SkeletonPtr getRootSkeleton() const override;
  
    // Documentation inherited
    void uniteSkeletons() override;
  
  private:
    /// Offset from the origin of body frame 1 to the ball joint position where
    /// the offset is expressed in body frame 1
    Eigen::Vector3d mOffset1;
  
    /// Offset from the origin of body frame 2 to the ball joint position where
    /// the offset is expressed in body frame 2
    Eigen::Vector3d mOffset2;
  
    /// Position constraint violation expressed in body frame 1
    Eigen::Vector3d mViolation;
  
    /// Linear map between constraint space and Cartesian space for body1
    Eigen::Matrix<double, 3, 6> mJacobian1;
  
    /// Linear map between constraint space and Cartesian space for body2
    Eigen::Matrix<double, 3, 6> mJacobian2;
  
    ///
    double mOldX[3];
  
    /// Index of applied impulse
    std::size_t mAppliedImpulseIndex;
  
  public:
    // To get byte-aligned Eigen vectors
    EIGEN_MAKE_ALIGNED_OPERATOR_NEW
  };
  
  }  // namespace constraint
  }  // namespace dart
  
  #endif  // DART_CONSTRAINT_BALLJOINTCONSTRAINT_HPP_
  
  