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SimSimulator Class Reference

An implementation of Baraff & Witkin's cloth simulation algorithm. More...

#include <freecloth/simulator/simSimulator.h>

Inheritance diagram for SimSimulator:

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Collaboration diagram for SimSimulator:

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List of all members.

Public Types

enum  ForceType {
  F_STRETCH, F_SHEAR, F_BEND, F_GRAVITY,
  F_DRAG, NB_FORCES
}
 The individual classes of forces.


Public Member Functions

 SimSimulator (const GeMesh &initialMesh)
const GeMesh & getMesh () const
const RCShdPtr< GeMesh > & getMeshPtr () const
void rewind ()
void step ()
BaTime::Instant getTime () const
 Retrieve the current simulation time.

void removeAllConstraints ()
 Remove all constraints on all vertices.

void setPosConstraintPlane (GeMesh::VertexId, const GeVector &)
void setPosConstraintLine (GeMesh::VertexId, const GeVector &)
 Constrain movement of the vertex to the given line.

void setPosConstraintFull (GeMesh::VertexId)
 Completely constrain the vertex, allowing no movement.

void setVelConstraint (GeMesh::VertexId, const GeVector &)
bool subStepsDone () const
void preSubSteps ()
void subStep ()
void postSubSteps ()
void setTimestep (Float)
 Mutator.

void setParams (const Params &)
 Mutator.

void setDensity (Float rho)
 Mutator.

void setPCGTolerance (Float)
 Mutator.

Float getTimestep () const
 Accessor.

const Params & getParams () const
 Accessor.

Float getDensity () const
 Accessor.

Float getPCGTolerance () const
 Accessor.

GeVector getVelocity (GeMesh::VertexId vid) const
 Only exposed for debugging purposes.

GeVector getForce (GeMesh::VertexId vid) const
 Only exposed for debugging purposes.

Float getEnergy (ForceType) const
 Only exposed for debugging purposes.

Float getTriEnergy (ForceType, GeMesh::FaceId) const
 Only exposed for debugging purposes.

GeVector getForce (ForceType type, GeMesh::VertexId vid) const
 Only exposed for debugging purposes.

GeVector getDampingForce (ForceType type, GeMesh::VertexId vid) const
 Only exposed for debugging purposes.

void setMesh (const GeMesh &)
 Only exposed for debugging purposes.


Private Types

typedef SimMatrix Matrix
typedef SimMatrix SymMatrix
typedef SimMatrix TridiagMatrix

Private Member Functions

void setupMass ()
void calcStretchShear (const GeMesh::FaceWrapper &face)
 Calculate values common to the stretch and shear conditions.

void calcStretch (const GeMesh::FaceWrapper &face, const CommonVars &cv, const GePoint x[3], const GePoint tp[3], const GeVector v0[3])
 Calculate the stretch condition and its derivatives.

void calcShear (const GeMesh::FaceWrapper &face, const CommonVars &cv, const GePoint x[3], const GePoint tp[3], const GeVector v0[3])
 Calculate the shear condition and its derivatives.

void calcBend (const GeMeshWingedEdge::HalfEdgeWrapper &edge)
 Calculate the bend condition and its derivatives.


Private Attributes

RCShdPtr< GeMesh > _initialMesh
RCShdPtr< GeMeshWingedEdge > _initialMeshWingedEdge
RCShdPtr< GeMesh > _mesh
Params _params
Float _rho
 Density of cloth ( kg / m^2 ).

Float _h
 Timestep.

Float _time
 Current time.

TridiagMatrix _M
 Variables from the [BarWit98], as defined in equations (6) and (14).

Float _totalMass
 Sum of diagonals of _M.

SimVector _f0
SymMatrix _df_dx
SymMatrix _df_dv
SimVector _v0
SimVector _z0
ModPCGSolver _modPCG
SimVector _f0i [NB_FORCES]
 For debugging.

SimVector _d0i [NB_FORCES]
 For debugging.

SymMatrix _df_dxi [NB_FORCES]
 For debugging.

SymMatrix _dd_dvi [NB_FORCES]
 For debugging.

SymMatrix _dd_dxi [NB_FORCES]
 For debugging.

Float _fenergy [NB_FORCES]
 Total energy of cloth.

Float _venergy
 Total energy of cloth.

Float _energy
 Total energy of cloth.

std::vector< Float > _trienergy [NB_FORCES]
 Total energy of cloth.

Detailed Description

An implementation of Baraff & Witkin's cloth simulation algorithm.

Using the simulation is fairly straightforward. The client supplies an initial mesh, which must have disc topology. The client also specifies the density of the cloth, which indirectly defines the mass of each triangle of the mesh. The client can also specify constraints on the cloth motion, constraining both the position and the velocity of individual nodes of the mesh.

Time starts at zero, and is advanced by a fixed timestep by calls to step(). The client can retrieve the mesh after each timestep. The simulation can be rewound to the beginning by calling rewind().

There are many parameters for the simulation algorithm. See [BarWit98] or the description in SimSimulator::Params for details.

References:

Definition at line 104 of file simSimulator.h.

Member Function Documentation

void SimSimulator::postSubSteps (    ) 
 

Finer grained simulation control - allows the client more control over the computation. See step() for details.

Definition at line 608 of file simSimulator.cpp.

References SimSimulator::ModPCGSolver::_A, _d0i, _energy, _f0i, _fenergy, _h, _time, SimSimulator::ModPCGSolver::result(), GeMeshTypes::VertexConstIterator, and GeMeshTypes::VertexIterator.

Referenced by step().

void SimSimulator::preSubSteps (    ) 
 

Finer grained simulation control - allows the client more control over the computation. See step() for details.

Definition at line 482 of file simSimulator.cpp.

References SimSimulator::ModPCGSolver::_A, SimSimulator::ModPCGSolver::_b, _d0i, _dd_dvi, _dd_dxi, _df_dxi, _energy, _f0i, _fenergy, SimSimulator::Params::_g, _h, SimSimulator::Params::_k_drag, _M, _time, _venergy, SimSimulator::ModPCGSolver::_z, calcBend(), calcStretchShear(), SimVector::clear(), SimVector::dot(), GeMeshWingedEdge::EdgeIterator, GeMeshTypes::FaceVertexId, and SimSimulator::ModPCGSolver::preStep().

Referenced by step().

void SimSimulator::rewind (    ) 
 

Rewind simulation time to zero, and return the mesh to its initial state.

Definition at line 318 of file simSimulator.cpp.

References SimSimulator::ModPCGSolver::_A, SimSimulator::ModPCGSolver::_b, _d0i, _dd_dvi, _dd_dxi, _df_dxi, _energy, _f0i, _fenergy, _time, _trienergy, _venergy, and ForceType.

void SimSimulator::setPosConstraintPlane (  GeMesh::VertexId   ,
const GeVector &   
) 
 

Constrain movement of the vertex to the plane defined by the given normal.

Definition at line 409 of file simSimulator.cpp.

References SimSimulator::ModPCGSolver::_S, GeVector::getUnit(), and GeMatrix3::outerProduct().

void SimSimulator::setupMass (    )  [private]
 

Fill the mass matrix (_M) using the initial mesh's triangles areas and the density parameter, as per [BarWit98] section 2.2.

Definition at line 361 of file simSimulator.cpp.

References _M, _rho, _totalMass, and GeMeshTypes::VertexId.

Referenced by setDensity().

void SimSimulator::setVelConstraint (  GeMesh::VertexId   ,
const GeVector &   
) 
 

Force the vertex to move with the specified velocity. This overrides any position constraints.

Definition at line 463 of file simSimulator.cpp.

References SimVector::size().

void SimSimulator::step (    ) 
 

Advance the simulation by one timestep. step() is equivalent to calling

Definition at line 471 of file simSimulator.cpp.

References postSubSteps(), preSubSteps(), subStep(), and subStepsDone().

void SimSimulator::subStep (    ) 
 

Finer grained simulation control - allows the client more control over the computation. See step() for details.

Definition at line 601 of file simSimulator.cpp.

References SimSimulator::ModPCGSolver::step().

Referenced by step().

bool SimSimulator::subStepsDone (    )  const
 

Finer grained simulation control - allows the client more control over the computation. See step() for details.

Definition at line 594 of file simSimulator.cpp.

References SimSimulator::ModPCGSolver::done().

Referenced by step().

The documentation for this class was generated from the following files:
Generated on Wed Apr 23 15:59:00 2003 for Freecloth by doxygen1.3-rc3