text: /*
   * Copyright (c) 2011-2019, The DART development contributors
   * All rights reserved.
   *
   * The list of contributors can be found at:
   *   https://github.com/dartsim/dart/blob/master/LICENSE
   *
   * This file is provided under the following "BSD-style" License:
   *   Redistribution and use in source and binary forms, with or
   *   without modification, are permitted provided that the following
   *   conditions are met:
   *   * 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.
   *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
   *   CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES,
   *   INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
   *   MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   *   DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
   *   CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
   *   USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
   *   AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   *   LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   *   ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   *   POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifndef DART_CONSTRAINT_CONSTRAINTBASE_HPP_
  #define DART_CONSTRAINT_CONSTRAINTBASE_HPP_
  
  #include <cstddef>
  
  #include "dart/dynamics/SmartPointer.hpp"
  
  namespace dart {
  
  namespace dynamics {
  class Skeleton;
  }  // namespace dynamics
  
  namespace constraint {
  
  /// ConstraintInfo
  struct ConstraintInfo
  {
    /// Impulse
    double* x;
  
    /// Lower bound of x
    double* lo;
  
    /// Upper bound of x
    double* hi;
  
    /// Bias term
    double* b;
  
    /// Slack variable
    double* w;
  
    /// Friction index
    int* findex;
  
    /// Inverse of time step
    double invTimeStep;
  };
  
  /// Constraint is a base class of concrete constraints classes
  class ConstraintBase
  {
  public:
    /// Return dimesion of this constranit
    std::size_t getDimension() const;
  
    /// Update constraint using updated Skeleton's states
    virtual void update() = 0;
  
    /// Fill LCP variables
    virtual void getInformation(ConstraintInfo* info) = 0;
  
    /// Apply unit impulse to constraint space
    virtual void applyUnitImpulse(std::size_t index) = 0;
  
    /// Get velocity change due to the uint impulse
    virtual void getVelocityChange(double* vel, bool withCfm) = 0;
  
    /// Excite the constraint
    virtual void excite() = 0;
  
    /// Unexcite the constraint
    virtual void unexcite() = 0;
  
    /// Apply computed constraint impulse to constrained skeletons
    virtual void applyImpulse(double* lambda) = 0;
  
    /// Return true if this constraint is active
    virtual bool isActive() const = 0;
  
    ///
    virtual dynamics::SkeletonPtr getRootSkeleton() const = 0;
  
    ///
    virtual void uniteSkeletons();
  
    ///
    static dynamics::SkeletonPtr compressPath(dynamics::SkeletonPtr skeleton);
  
    ///
    static dynamics::SkeletonPtr getRootSkeleton(dynamics::SkeletonPtr skeleton);
  
    //----------------------------------------------------------------------------
    // Friendship
    //----------------------------------------------------------------------------
  
    friend class ConstraintSolver;
    friend class ConstrainedGroup;
  
  protected:
    /// Default contructor
    ConstraintBase();
  
    /// Destructor
    virtual ~ConstraintBase();
  
  protected:
    /// Dimension of constraint
    std::size_t mDim;
  };
  
  } // namespace constraint
  } // namespace dart
  
  #endif  // DART_CONSTRAINT_CONSTRAINTBASE_HPP_
  
  