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// Geometric Tools, LLC
// Copyright (c) 1998-2014
// Distributed under the Boost Software License, Version 1.0.
// http://www.boost.org/LICENSE_1_0.txt
// http://www.geometrictools.com/License/Boost/LICENSE_1_0.txt
//
// File Version: 5.0.1 (2010/10/01)
#include "Wm5PhysicsPCH.h"
#include "Wm5MassSpringArbitrary.h"
#include "Wm5Memory.h"
namespace Wm5
{
//----------------------------------------------------------------------------
template <class Real, class TVector>
MassSpringArbitrary<Real,TVector>::MassSpringArbitrary (int numParticles,
int numSprings, Real step)
:
ParticleSystem<Real,TVector>(numParticles, step)
{
mNumSprings = numSprings;
mSprings = new1<Spring>(mNumSprings);
memset(mSprings, 0, mNumSprings*sizeof(Spring));
mAdjacent = new1<std::set<int> >(mNumParticles);
}
//----------------------------------------------------------------------------
template <class Real, class TVector>
MassSpringArbitrary<Real,TVector>::~MassSpringArbitrary ()
{
delete1(mSprings);
delete1(mAdjacent);
}
//----------------------------------------------------------------------------
template <class Real, class TVector>
int MassSpringArbitrary<Real,TVector>::GetNumSprings () const
{
return mNumSprings;
}
//----------------------------------------------------------------------------
template <class Real, class TVector>
void MassSpringArbitrary<Real,TVector>::SetSpring (int spring, int particle0,
int particle1, Real constant, Real length)
{
mSprings[spring].Particle0 = particle0;
mSprings[spring].Particle1 = particle1;
mSprings[spring].Constant = constant;
mSprings[spring].Length = length;
mAdjacent[particle0].insert(spring);
mAdjacent[particle1].insert(spring);
}
//----------------------------------------------------------------------------
template <class Real, class TVector>
void MassSpringArbitrary<Real,TVector>::GetSpring (int spring, int& particle0,
int& particle1, Real& constant, Real& length) const
{
particle0 = mSprings[spring].Particle0;
particle1 = mSprings[spring].Particle1;
constant = mSprings[spring].Constant;
length = mSprings[spring].Length;
}
//----------------------------------------------------------------------------
template <class Real, class TVector>
Real& MassSpringArbitrary<Real,TVector>::Constant (int spring)
{
return mSprings[spring].Constant;
}
//----------------------------------------------------------------------------
template <class Real, class TVector>
Real& MassSpringArbitrary<Real,TVector>::Length (int spring)
{
return mSprings[spring].Length;
}
//----------------------------------------------------------------------------
template <class Real, class TVector>
TVector MassSpringArbitrary<Real,TVector>::Acceleration (int i, Real time,
const TVector* positions, const TVector* velocities)
{
// Compute spring forces on position X[i]. The positions are not
// necessarily m_akPosition since the RK4 solver in ParticleSystem
// evaluates the acceleration function at intermediate positions.
TVector acceleration = ExternalAcceleration(i, time, positions,
velocities);
TVector diff, force;
Real ratio;
std::set<int>::iterator iter = mAdjacent[i].begin();
std::set<int>::iterator end = mAdjacent[i].end();
for (/**/; iter != end; ++iter)
{
// Process a spring connected to particle i.
const Spring& spring = mSprings[*iter];
if (i != spring.Particle0)
{
diff = positions[spring.Particle0] - positions[i];
}
else
{
diff = positions[spring.Particle1] - positions[i];
}
ratio = spring.Length/diff.Length();
force = spring.Constant*((Real)1 - ratio)*diff;
acceleration += mInvMasses[i]*force;
}
return acceleration;
}
//----------------------------------------------------------------------------
template <class Real, class TVector>
TVector MassSpringArbitrary<Real,TVector>::ExternalAcceleration (int, Real,
const TVector*, const TVector*)
{
return TVector::ZERO;
}
//----------------------------------------------------------------------------
//----------------------------------------------------------------------------
// Explicit instantiation.
//----------------------------------------------------------------------------
template WM5_PHYSICS_ITEM
class MassSpringArbitrary<float,Vector2f>;
template WM5_PHYSICS_ITEM
class MassSpringArbitrary<float,Vector3f>;
template WM5_PHYSICS_ITEM
class MassSpringArbitrary<double,Vector2d>;
template WM5_PHYSICS_ITEM
class MassSpringArbitrary<double,Vector3d>;
//----------------------------------------------------------------------------
}
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