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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)
#ifndef WM5MASSSPRINGVOLUME_H
#define WM5MASSSPRINGVOLUME_H
#include "Wm5PhysicsLIB.h"
#include "Wm5ParticleSystem.h"
namespace Wm5
{
template <typename Real, typename TVector>
class WM5_PHYSICS_ITEM MassSpringVolume : public ParticleSystem<Real,TVector>
{
public:
// Construction and destruction. This class represents an SxRxC array of
// masses lying on in a volume and connected by an array of springs. The
// masses are indexed by mass[s][r][c] for 0 <= s < S, 0 <= r < R, and
// 0 <= c < C. The mass at interior position X[s][r][c] is connected by
// springs to the masses at positions X[s][r-1][c], X[s][r+1][c],
// X[s][r][c-1], X[s][r][c+1], X[s-1][r][c], and X[s+1][r][c]. Boundary
// masses have springs connecting them to the obvious neighbors ("face"
// mass has 5 neighbors, "edge" mass has 4 neighbors, "corner" mass has 3
// neighbors). The masses are arranged in lexicographical order:
// position[c+C*(r+R*s)] = X[s][r][c] for 0 <= s < S, 0 <= r < R, and
// 0 <= c < C. The other arrays are stored similarly.
MassSpringVolume (int numSlices, int numRows, int numCols, Real step);
virtual ~MassSpringVolume ();
int GetNumSlices () const;
int GetNumRows () const;
int GetNumCols () const;
void SetMass (int slice, int row, int col, Real mass);
Real GetMass (int slice, int row, int col) const;
TVector*** Positions3D () const;
TVector& Position (int slice, int row, int col);
TVector*** Velocities3D () const;
TVector& Velocity (int slice, int row, int col);
// Each interior mass at (s,r,c) has 6 adjacent springs. Face masses
// have only 5 neighbors, edge masses have only 4 neighbors, and corner
// masses have only 3 neighbors. Each mass provides access to 3 adjacent
// springs at (s,r,c+1), (s,r+1,c), and (s+1,r,c). The face, edge, and
// corner masses provide access to only an appropriate subset of these.
// The caller is responsible for ensuring the validity of the (s,r,c)
// inputs.
Real& ConstantS (int slice, int row, int col); // spring to (s+1,r,c)
Real& LengthS (int slice, int row, int col); // spring to (s+1,r,c)
Real& ConstantR (int slice, int row, int col); // spring to (s,r+1,c)
Real& LengthR (int slice, int row, int col); // spring to (s,r+1,c)
Real& ConstantC (int slice, int row, int col); // spring to (s,r,c+1)
Real& LengthC (int slice, int row, int col); // spring to (s,r,c+1)
// Callback for acceleration (ODE solver uses x" = F/m) applied to
// particle i. The positions and velocities are not necessarily
// mPositions and mVelocities since the ODE solver evaluates the
// impulse function at intermediate positions.
virtual TVector Acceleration (int i, Real time,
const TVector* positions, const TVector* velocities);
// The default external force is zero. Derive a class from this one to
// provide nonzero external forces such as gravity, wind, friction,
// and so on. This function is called by Acceleration(...) to append the
// acceleration F/m generated by the external force F.
virtual TVector ExternalAcceleration (int i, Real time,
const TVector* positions, const TVector* velocities);
protected:
using ParticleSystem<Real,TVector>::mInvMasses;
using ParticleSystem<Real,TVector>::mPositions;
using ParticleSystem<Real,TVector>::mVelocities;
int GetIndex (int slice, int row, int col) const;
void GetCoordinates (int i, int& slice, int& row, int& col) const;
int mNumSlices; // S
int mNumRows; // R
int mNumCols; // C
int mSliceQuantity; // R*C
TVector*** mPositionGrid; // S-by-R-by-C
TVector*** mVelocityGrid; // S-by-R-by-C
int mNumSlicesM1; // S-1
int mNumRowsM1; // R-1
int mNumColsM1; // C-1
Real*** mConstantsS; // (S-1)-by-R-by-C
Real*** mLengthsS; // (S-1)-by-R-by-C
Real*** mConstantsR; // S-by-(R-1)-by-C
Real*** mLengthsR; // S-by-(R-1)-by-C
Real*** mConstantsC; // S-by-R-by-(C-1)
Real*** mLengthsC; // S-by-R-by-(C-1)
};
typedef MassSpringVolume<float,Vector3f> MassSpringVolume3f;
typedef MassSpringVolume<double,Vector3d> MassSpringVolume3d;
}
#endif
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