Force_MobilityLinearSpring.h

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#ifndef SimTK_SIMBODY_FORCE_MOBILITY_LINEAR_SPRING_H_
#define SimTK_SIMBODY_FORCE_MOBILITY_LINEAR_SPRING_H_

/* -------------------------------------------------------------------------- *
 *                               Simbody(tm)                                  *
 * -------------------------------------------------------------------------- *
 * This is part of the SimTK biosimulation toolkit originating from           *
 * Simbios, the NIH National Center for Physics-Based Simulation of           *
 * Biological Structures at Stanford, funded under the NIH Roadmap for        *
 * Medical Research, grant U54 GM072970. See https://simtk.org/home/simbody.  *
 *                                                                            *
 * Portions copyright (c) 2008-13 Stanford University and the Authors.        *
 * Authors: Peter Eastman, Michael Sherman                                    *
 * Contributors:                                                              *
 *                                                                            *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may    *
 * not use this file except in compliance with the License. You may obtain a  *
 * copy of the License at http://www.apache.org/licenses/LICENSE-2.0.         *
 *                                                                            *
 * Unless required by applicable law or agreed to in writing, software        *
 * distributed under the License is distributed on an "AS IS" BASIS,          *
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.   *
 * See the License for the specific language governing permissions and        *
 * limitations under the License.                                             *
 * -------------------------------------------------------------------------- */

#include "SimTKcommon.h"
#include "simbody/internal/Force.h"

namespace SimTK {

class SimTK_SIMBODY_EXPORT Force::MobilityLinearSpring : public Force {
public:
    MobilityLinearSpring(GeneralForceSubsystem& forces, 
                         const MobilizedBody&   mobod, 
                         MobilizerQIndex        whichQ, 
                         Real                   defaultStiffness, 
                         Real                   defaultQZero);
    
    MobilityLinearSpring() {}

    MobilityLinearSpring& setDefaultStiffness(Real defaultStiffness);


    MobilityLinearSpring& setDefaultQZero(Real defaultQZero);

    Real getDefaultStiffness() const;
    Real getDefaultQZero() const;

    const MobilityLinearSpring& setStiffness(State&     state, 
                                             Real       stiffness) const;

    const MobilityLinearSpring& setQZero(State&     state, 
                                         Real       qZero) const;

    Real getStiffness(const State& state) const;

    Real getQZero(const State& state) const;

    MobilityLinearSpring(GeneralForceSubsystem& forces, 
                         const MobilizedBody&   mobod, 
                         int                    whichQ, 
                         Real                   defaultStiffness, 
                         Real                   defaultQZero)
    {   // Invoke the other constructor.
        new(this) MobilityLinearSpring(forces, mobod, MobilizerQIndex(whichQ),
                                       defaultStiffness, defaultQZero);
    }
    SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS(MobilityLinearSpring, 
                                             MobilityLinearSpringImpl, Force);
};

} // namespace SimTK

#endif // SimTK_SIMBODY_FORCE_MOBILITY_LINEAR_SPRING_H_