spring.h

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/* This file is part of StepCore library.
   Copyright (C) 2007 Vladimir Kuznetsov <ks.vladimir@gmail.com>

   StepCore library is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   StepCore library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with StepCore; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#ifndef STEPCORE_SPRING_H
#define STEPCORE_SPRING_H

#include "world.h"
#include "object.h"
#include "particle.h"
#include "rigidbody.h"
#include "vector.h"

#include <QString>
#include <cmath>

namespace StepCore
{

class Spring;

class SpringErrors: public ObjectErrors
{
    STEPCORE_OBJECT(SpringErrors)

public:
    SpringErrors(Item* owner = NULL)
        : ObjectErrors(owner), _restLengthVariance(0), _stiffnessVariance(0),
          _dampingVariance(0), _localPosition1Variance(0,0), _localPosition2Variance(0,0) {}

    Spring* spring() const;

    double restLengthVariance() const { return _restLengthVariance; }
    void   setRestLengthVariance(double restLengthVariance) {
        _restLengthVariance = restLengthVariance; }

    double lengthVariance() const;

    double stiffnessVariance() const { return _stiffnessVariance; }
    void   setStiffnessVariance(double stiffnessVariance) {
        _stiffnessVariance = stiffnessVariance; }

    double dampingVariance() const { return _dampingVariance; }
    void   setDampingVariance(double dampingVariance) {
        _dampingVariance = dampingVariance; }

    Vector2d localPosition1Variance() const { return _localPosition1Variance; }
    void setLocalPosition1Variance(const Vector2d& localPosition1Variance) {
        _localPosition1Variance = localPosition1Variance; }

    Vector2d localPosition2Variance() const { return _localPosition2Variance; }
    void setLocalPosition2Variance(const Vector2d& localPosition2Variance) {
        _localPosition2Variance = localPosition2Variance; }

    Vector2d position1Variance() const;
    Vector2d position2Variance() const;

    Vector2d velocity1Variance() const;
    Vector2d velocity2Variance() const;

    double forceVariance() const;

protected:
    double _restLengthVariance;
    double _stiffnessVariance;
    double _dampingVariance;

    StepCore::Vector2d _localPosition1Variance;
    StepCore::Vector2d _localPosition2Variance;

    friend class Spring;
};


class Spring: public Item, public Force
{
    STEPCORE_OBJECT(Spring)

public:
    explicit Spring(double restLength = 0, double stiffness = 1, double damping = 0,
                Item* body1 = 0, Item* body2 = 0);

    void calcForce(bool calcVariances);

    double restLength() const { return _restLength; }
    void   setRestLength(double restLength) { _restLength = restLength; }

    double length() const { return (position2()-position1()).norm(); }

    double stiffness() const { return _stiffness; }
    void   setStiffness(double stiffness) { _stiffness = stiffness; }

    double damping() const { return _damping; }
    void setDamping(double damping) { _damping = damping; }

    Object* body1() const { return _body1; }
    void setBody1(Object* body1);

    Object* body2() const { return _body2; }
    void setBody2(Object* body2);

    Vector2d localPosition1() const { return _localPosition1; }
    void setLocalPosition1(const Vector2d& localPosition1) { _localPosition1 = localPosition1; }

    Vector2d localPosition2() const { return _localPosition2; }
    void setLocalPosition2(const Vector2d& localPosition2) { _localPosition2 = localPosition2; }

    Vector2d position1() const;
    //void setPosition1(const Vector2d& position1) { if(!_body1) _position1 = position1; }

    Vector2d position2() const;
    //void setPosition2(const Vector2d& position2) { if(!_body2) _position2 = position2; }
    
    Vector2d velocity1() const;

    Vector2d velocity2() const;

    double force() const;

    Particle* particle1() const { return _p1; }
    Particle* particle2() const { return _p2; }
    RigidBody* rigidBody1() const { return _r1; }
    RigidBody* rigidBody2() const { return _r2; }

    //void worldItemRemoved(Item* item);
    //void setWorld(World* world);

    SpringErrors* springErrors() { return static_cast<SpringErrors*>(objectErrors()); }

protected:
    ObjectErrors* createObjectErrors() { return new SpringErrors(this); }

    Object* _body1;
    Object* _body2;
    double _restLength;
    double _stiffness;
    double _damping;
    Vector2d _localPosition1;
    Vector2d _localPosition2;

    Particle*  _p1;
    Particle*  _p2;
    RigidBody* _r1;
    RigidBody* _r2;

    friend class SpringErrors;
};

} // namespace StepCore

#endif