Force.h

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#ifndef SimTK_SIMBODY_FORCE_H_
#define SimTK_SIMBODY_FORCE_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/common.h"
#include "simbody/internal/GeneralForceSubsystem.h"

namespace SimTK {

class SimbodyMatterSubsystem;
class GeneralForceSubsystem;
class MobilizedBody;
class Force;
class ForceImpl;

// We only want the template instantiation to occur once. This symbol is defined
// in the SimTK core compilation unit that defines the Force class but should 
// not be defined any other time.
#ifndef SimTK_SIMBODY_DEFINING_FORCE
    extern template class PIMPLHandle<Force, ForceImpl, true>;
#endif

class SimTK_SIMBODY_EXPORT Force : public PIMPLHandle<Force, ForceImpl, true> {
public:
    void disable(State&) const;
    void enable(State&) const;
    bool isDisabled(const State&) const;
    void setDisabledByDefault(bool shouldBeDisabled);
    bool isDisabledByDefault() const;
    void calcForceContribution(const State&          state,
                               Vector_<SpatialVec>&  bodyForces,
                               Vector_<Vec3>&        particleForces,
                               Vector&               mobilityForces) const;
    Real calcPotentialEnergyContribution(const State& state) const;
    Force() {}
    operator ForceIndex() const {return getForceIndex();}
    const GeneralForceSubsystem& getForceSubsystem() const;
    ForceIndex getForceIndex() const;
    class TwoPointLinearSpring;
    class TwoPointLinearDamper;
    class TwoPointConstantForce;
    class MobilityLinearSpring;
    class MobilityLinearDamper;
    class MobilityConstantForce;
    class MobilityLinearStop;
    class MobilityDiscreteForce;
    class DiscreteForces;
    class LinearBushing;
    class ConstantForce;
    class ConstantTorque;
    class GlobalDamper;
    class Thermostat;
    class UniformGravity;
    class Gravity;
    class Custom;
    
    class TwoPointLinearSpringImpl;
    class TwoPointLinearDamperImpl;
    class TwoPointConstantForceImpl;
    class MobilityLinearSpringImpl;
    class MobilityLinearDamperImpl;
    class MobilityConstantForceImpl;
    class MobilityLinearStopImpl;
    class MobilityDiscreteForceImpl;
    class DiscreteForcesImpl;
    class LinearBushingImpl;
    class ConstantForceImpl;
    class ConstantTorqueImpl;
    class GlobalDamperImpl;
    class ThermostatImpl;
    class UniformGravityImpl;
    class GravityImpl;
    class CustomImpl;

protected:
    explicit Force(ForceImpl* r) : HandleBase(r) { }
};


class SimTK_SIMBODY_EXPORT Force::TwoPointLinearSpring : public Force {
public:
    TwoPointLinearSpring(GeneralForceSubsystem& forces, const MobilizedBody& body1, const Vec3& station1, const MobilizedBody& body2, const Vec3& station2, Real k, Real x0);
    
    TwoPointLinearSpring() {}

    SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS(TwoPointLinearSpring, TwoPointLinearSpringImpl, Force);
};

class SimTK_SIMBODY_EXPORT Force::TwoPointLinearDamper: public Force {
public:
    TwoPointLinearDamper(GeneralForceSubsystem& forces, const MobilizedBody& body1, const Vec3& station1, const MobilizedBody& body2, const Vec3& station2, Real damping);
    
    TwoPointLinearDamper() {}

    SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS(TwoPointLinearDamper, TwoPointLinearDamperImpl, Force);
};

class SimTK_SIMBODY_EXPORT Force::TwoPointConstantForce: public Force {
public:
    TwoPointConstantForce(GeneralForceSubsystem& forces, const MobilizedBody& body1, const Vec3& station1, const MobilizedBody& body2, const Vec3& station2, Real force);
    
    TwoPointConstantForce() {}

    SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS(TwoPointConstantForce, TwoPointConstantForceImpl, Force);
};


class SimTK_SIMBODY_EXPORT Force::ConstantForce: public Force {
public:
    ConstantForce(GeneralForceSubsystem& forces, const MobilizedBody& body, const Vec3& station, const Vec3& force);
    
    ConstantForce() {}

    SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS(ConstantForce, ConstantForceImpl, Force);
};

class SimTK_SIMBODY_EXPORT Force::ConstantTorque: public Force {
public:
    ConstantTorque(GeneralForceSubsystem& forces, const MobilizedBody& body, const Vec3& torque);
    
    ConstantTorque() {}

    SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS(ConstantTorque, ConstantTorqueImpl, Force);
};

class SimTK_SIMBODY_EXPORT Force::GlobalDamper : public Force {
public:
    GlobalDamper(GeneralForceSubsystem& forces, const SimbodyMatterSubsystem& matter, Real damping);
    
    GlobalDamper() {}

    SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS(GlobalDamper, GlobalDamperImpl, Force);
};

class SimTK_SIMBODY_EXPORT Force::UniformGravity : public Force {
public:
    UniformGravity(GeneralForceSubsystem& forces, 
                   const SimbodyMatterSubsystem& matter, 
                   const Vec3& g, Real zeroHeight=0);
    
    UniformGravity() {}

    Vec3 getGravity() const;
    void setGravity(const Vec3& g);
    Real getZeroHeight() const;
    void setZeroHeight(Real height);
    SimTK_INSERT_DERIVED_HANDLE_DECLARATIONS(UniformGravity, UniformGravityImpl, Force);
};

} // namespace SimTK

#endif // SimTK_SIMBODY_FORCE_H_