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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
*/
#include "spring.h"
#include "types.h"
#include <algorithm>
#include <cmath>
#include <QtGlobal>
namespace StepCore {
STEPCORE_META_OBJECT(Spring, QT_TRANSLATE_NOOP("ObjectClass", "Spring"), QT_TR_NOOP("Massless spring which can be connected to bodies"), 0,
STEPCORE_SUPER_CLASS(Item) STEPCORE_SUPER_CLASS(Force),
STEPCORE_PROPERTY_RW(double, restLength, QT_TRANSLATE_NOOP("PropertyName", "restLength"), QT_TRANSLATE_NOOP("Units", "m"), QT_TR_NOOP("Rest length"), restLength, setRestLength)
STEPCORE_PROPERTY_R_D(double, length, QT_TRANSLATE_NOOP("PropertyName", "length"), QT_TRANSLATE_NOOP("Units", "m"), QT_TR_NOOP("Current length"), length)
STEPCORE_PROPERTY_RW(double, stiffness, QT_TRANSLATE_NOOP("PropertyName", "stiffness"), QT_TRANSLATE_NOOP("Units", "N/m"), QT_TR_NOOP("Stiffness"), stiffness, setStiffness)
STEPCORE_PROPERTY_RW(double, damping, QT_TRANSLATE_NOOP("PropertyName", "damping"), QT_TRANSLATE_NOOP("Units", "N s/m"), QT_TR_NOOP("Damping"), damping, setDamping)
STEPCORE_PROPERTY_RW(Object*, body1, QT_TRANSLATE_NOOP("PropertyName", "body1"), STEPCORE_UNITS_NULL, QT_TR_NOOP("Body1"), body1, setBody1)
STEPCORE_PROPERTY_RW(Object*, body2, QT_TRANSLATE_NOOP("PropertyName", "body2"), STEPCORE_UNITS_NULL, QT_TR_NOOP("Body2"), body2, setBody2)
STEPCORE_PROPERTY_RW(StepCore::Vector2d, localPosition1, QT_TRANSLATE_NOOP("PropertyName", "localPosition1"), QT_TRANSLATE_NOOP("Units", "m"),
QT_TR_NOOP("Local position 1"), localPosition1, setLocalPosition1)
STEPCORE_PROPERTY_RW(StepCore::Vector2d, localPosition2, QT_TRANSLATE_NOOP("PropertyName", "localPosition2"), QT_TRANSLATE_NOOP("Units", "m"),
QT_TR_NOOP("Local position 2"), localPosition2, setLocalPosition2)
STEPCORE_PROPERTY_R_D(StepCore::Vector2d, position1, QT_TRANSLATE_NOOP("PropertyName", "position1"), QT_TRANSLATE_NOOP("Units", "m"), QT_TR_NOOP("Position1"), position1)
STEPCORE_PROPERTY_R_D(StepCore::Vector2d, position2, QT_TRANSLATE_NOOP("PropertyName", "position2"), QT_TRANSLATE_NOOP("Units", "m"), QT_TR_NOOP("Position2"), position2)
STEPCORE_PROPERTY_R_D(double, force, QT_TRANSLATE_NOOP("PropertyName", "force"), QT_TRANSLATE_NOOP("Units", "N"), QT_TR_NOOP("Spring tension force"), force)
)
STEPCORE_META_OBJECT(SpringErrors, QT_TRANSLATE_NOOP("ObjectClass", "SpringErrors"), QT_TR_NOOP("Errors class for Spring"), 0,
STEPCORE_SUPER_CLASS(ObjectErrors),
STEPCORE_PROPERTY_RW(double, restLengthVariance, QT_TRANSLATE_NOOP("PropertyName", "restLengthVariance"), QT_TRANSLATE_NOOP("Units", "m"),
QT_TR_NOOP("Rest length variance"), restLengthVariance, setRestLengthVariance)
STEPCORE_PROPERTY_R_D(double, lengthVariance, QT_TRANSLATE_NOOP("PropertyName", "lengthVariance"), QT_TRANSLATE_NOOP("Units", "m"),
QT_TR_NOOP("Current length variance"), lengthVariance)
STEPCORE_PROPERTY_RW(double, stiffnessVariance, QT_TRANSLATE_NOOP("PropertyName", "stiffnessVariance"), QT_TRANSLATE_NOOP("Units", "N/m"),
QT_TR_NOOP("Stiffness variance"), stiffnessVariance, setStiffnessVariance)
STEPCORE_PROPERTY_RW(double, dampingVariance, QT_TRANSLATE_NOOP("PropertyName", "dampingVariance"), QT_TRANSLATE_NOOP("Units", "N/m"),
QT_TR_NOOP("Damping variance"), dampingVariance, setDampingVariance)
STEPCORE_PROPERTY_RW(StepCore::Vector2d, localPosition1Variance, QT_TRANSLATE_NOOP("PropertyName", "localPosition1Variance"), QT_TRANSLATE_NOOP("Units", "m"),
QT_TR_NOOP("Local position 1 variance"), localPosition1Variance, setLocalPosition1Variance)
STEPCORE_PROPERTY_RW(StepCore::Vector2d, localPosition2Variance, QT_TRANSLATE_NOOP("PropertyName", "localPosition2Variance"), QT_TRANSLATE_NOOP("Units", "m"),
QT_TR_NOOP("Local position 2 variance"), localPosition2Variance, setLocalPosition2Variance)
STEPCORE_PROPERTY_R_D(StepCore::Vector2d, position1Variance, QT_TRANSLATE_NOOP("PropertyName", "position1Variance"), QT_TRANSLATE_NOOP("Units", "m"),
QT_TR_NOOP("Position1 variance"), position1Variance)
STEPCORE_PROPERTY_R_D(StepCore::Vector2d, position2Variance, QT_TRANSLATE_NOOP("PropertyName", "position2Variance"), QT_TRANSLATE_NOOP("Units", "m"),
QT_TR_NOOP("Position2 variance"), position2Variance)
STEPCORE_PROPERTY_R_D(double, forceVariance, QT_TRANSLATE_NOOP("PropertyName", "forceVariance"), QT_TRANSLATE_NOOP("Units", "N"),
QT_TR_NOOP("Spring tension force variance"), forceVariance)
)
Spring* SpringErrors::spring() const
{
return static_cast<Spring*>(owner());
}
Spring::Spring(double restLength, double stiffness, double damping, Item* body1, Item* body2)
: _restLength(restLength),
_stiffness(stiffness), _damping(damping),
_localPosition1(0,0), _localPosition2(0,0)
{
setColor(0xff00ff00);
setBody1(body1);
setBody2(body2);
}
void Spring::calcForce(bool calcVariances)
{
if(!_body1 && !_body2) return;
Vector2d position1 = this->position1();
Vector2d position2 = this->position2();
Vector2d r = position2 - position1;
Vector2d v = velocity2() - velocity1();
double l = r.norm();
if(l == 0) return; // XXX: take orientation from previous step
double dl = l - _restLength;
double vr = v.dot(r);
Vector2d force = (_stiffness*dl + _damping*vr/l) / l * r;
if(_p1) _p1->applyForce(force);
else if(_r1) _r1->applyForce(force, position1);
force = -force;
if(_p2) _p2->applyForce(force);
else if(_r2) _r2->applyForce(force, position2);
if(calcVariances) {
SpringErrors* se = springErrors();
Vector2d rV = se->position2Variance() + se->position1Variance();
Vector2d vV = se->velocity2Variance() + se->velocity1Variance();
Vector2d forceV = (se->_restLengthVariance * square(_stiffness) +
se->_stiffnessVariance * square(dl) +
se->_dampingVariance * square(vr/l) +
vV.dot( (_damping/l*r).cwise().square() )
)/square(l)*r.cwise().square();
forceV[0] += rV[0] * square(_stiffness*( 1 - _restLength/l*(1 - square(r[0]/l)) ) +
_damping/(l*l)*( v[0]*r[0] + vr - 2*vr*square(r[0]/l) )) +
rV[1] * square(_stiffness*_restLength*r[0]*r[1]/(l*l*l) +
_damping/(l*l)*( v[1]*r[0] - 2*vr*r[0]*r[1]/(l*l) ));
forceV[1] += rV[1] * square(_stiffness*( 1 - _restLength/l*(1 - square(r[1]/l)) ) +
_damping/(l*l)*( v[1]*r[1] + vr - 2*vr*square(r[1]/l) )) +
rV[0] * square(_stiffness*_restLength*r[0]*r[1]/(l*l*l) +
_damping/(l*l)*( v[0]*r[1] - 2*vr*r[0]*r[1]/(l*l) ));
// TODO: position1() and force is corelated, we should take it into account
if(_p1) _p1->particleErrors()->applyForceVariance(forceV);
else if(_r1) _r1->rigidBodyErrors()->applyForceVariance(force, position1,
forceV, se->position1Variance() );
if(_p2) _p2->particleErrors()->applyForceVariance(forceV);
else if(_r2) _r2->rigidBodyErrors()->applyForceVariance(force, position2,
forceV, se->position2Variance() );
}
}
void Spring::setBody1(Object* body1)
{
if(body1) {
if(body1->metaObject()->inherits<Particle>()) {
_body1 = body1;
_p1 = static_cast<Particle*>(body1);
_r1 = NULL;
return;
} else if(body1->metaObject()->inherits<RigidBody>()) {
_body1 = body1;
_p1 = NULL;
_r1 = static_cast<RigidBody*>(body1);
return;
}
}
_body1 = NULL;
_p1 = NULL;
_r1 = NULL;
}
void Spring::setBody2(Object* body2)
{
if(body2) {
if(body2->metaObject()->inherits<Particle>()) {
_body2 = body2;
_p2 = static_cast<Particle*>(body2);
_r2 = NULL;
return;
} else if(body2->metaObject()->inherits<RigidBody>()) {
_body2 = body2;
_p2 = NULL;
_r2 = static_cast<RigidBody*>(body2);
return;
}
}
_body2 = NULL;
_p2 = NULL;
_r2 = NULL;
}
Vector2d Spring::position1() const
{
if(_p1) return _p1->position() + _localPosition1;
else if(_r1) return _r1->pointLocalToWorld(_localPosition1);
else return _localPosition1;
}
Vector2d SpringErrors::position1Variance() const
{
if(spring()->_p1)
return spring()->_p1->particleErrors()->positionVariance() + _localPosition1Variance;
// XXX: TODO
//RigidBody* _r1 = dynamic_cast<RigidBody*>(_body1);
//if(_r1) return _r1->pointLocalToWorld(_localPosition1);
#ifdef __GNUC__
#warning variance calculation for spring connected to rigidbody is not finished !
#warning consider unification of some part of Particle and RigidBody
#endif
else return _localPosition1Variance;
}
Vector2d Spring::position2() const
{
if(_p2) return _p2->position() + _localPosition2;
else if(_r2) return _r2->pointLocalToWorld(_localPosition2);
else return _localPosition2;
}
Vector2d SpringErrors::position2Variance() const
{
if(spring()->_p2)
return spring()->_p2->particleErrors()->positionVariance() + _localPosition2Variance;
// XXX: TODO
//RigidBody* _r2 = dynamic_cast<RigidBody*>(_body2);
//if(_r2) return _r2->pointLocalToWorld(_localPosition2);
else return _localPosition2Variance;
}
double SpringErrors::lengthVariance() const
{
Vector2d r = spring()->position2() - spring()->position1();
Vector2d rV = position2Variance() + position1Variance();
return (r[0]*r[0]*rV[0] + r[1]*r[1]*rV[1])/r.squaredNorm();
}
Vector2d Spring::velocity1() const
{
if(_p1) return _p1->velocity();
else if(_r1) return _r1->velocityLocal(_localPosition1);
else return Vector2d::Zero();
}
Vector2d SpringErrors::velocity1Variance() const
{
if(spring()->_p1)
return spring()->_p1->particleErrors()->velocityVariance();
// XXX: TODO
//RigidBody* _r1 = dynamic_cast<RigidBody*>(_body1);
//if(_r1) return _r1->pointLocalToWorld(_localPosition1);
else return Vector2d::Zero();
}
Vector2d Spring::velocity2() const
{
if(_p2) return _p2->velocity();
else if(_r2) return _r2->velocityLocal(_localPosition2);
else return Vector2d::Zero();
}
Vector2d SpringErrors::velocity2Variance() const
{
if(spring()->_p2)
return spring()->_p2->particleErrors()->velocityVariance();
// XXX: TODO
//RigidBody* _r2 = dynamic_cast<RigidBody*>(_body2);
//if(_r2) return _r2->pointLocalToWorld(_localPosition2);
else return Vector2d::Zero();
}
double Spring::force() const
{
Vector2d r = position2() - position1();
Vector2d v = velocity2() - velocity1();
double l = r.norm();
return _stiffness * (l - _restLength) +
_damping * v.dot(r)/l;
}
double SpringErrors::forceVariance() const
{
Spring* s = spring();
Vector2d r = s->position2() - s->position1();
Vector2d v = s->velocity2() - s->velocity1();
Vector2d rV = position2Variance() + position1Variance();
Vector2d vV = velocity2Variance() + velocity1Variance();
double l = r.norm();
double dl = l - s->restLength();
// XXX: CHECKME
return square(dl) * _stiffnessVariance +
square(s->stiffness()) * _restLengthVariance +
square(v.dot(r)/l) * _dampingVariance +
(s->damping()/l*r).cwise().square().dot(vV) +
(( s->stiffness() - s->damping()*v.dot(r) / (l*l) ) / l * r +
s->damping() / l * v).cwise().square().dot(rV);
}
/*
void Spring::worldItemRemoved(Item* item)
{
if(item == NULL) return;
else if(item == _body1) setBody1(NULL);
else if(item == _body2) setBody2(NULL);
}
*/
#if 0
void Spring::setWorld(World* world)
{
if(world == NULL) {
setBody1(NULL);
setBody2(NULL);
} else if(this->world() != NULL) {
#ifdef __GNUC__
#warning Use map instead of search-by-name here !
#endif
if(_body1 != NULL) setBody1(world->item(body1()->name())); //XXX
if(_body2 != NULL) setBody2(world->item(body2()->name())); //XXX
}
Item::setWorld(world);
}
#endif
} // namespace StepCore
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