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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:

[legend]Collaboration diagram for SimSimulator:

[legend]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 Methods
	SimSimulator (const GeMesh &initialMesh)
const GeMesh &	getMesh () const
const RCShdPtr< GeMesh > &	getMeshPtr () const
void	rewind ()
	Rewind simulation time to zero, and return the mesh to its initial state.
void	step ()
	Advance the simulation by one timestep. step() is equivalent to calling - preSubSteps() - repeated subStep() calls - postSubSteps().
BaTime::Instant	getTime () const
	Retrieve the current simulation time.
void	removeAllConstraints ()
	Remove all constraints on all vertices.
void	setPosConstraintPlane (GeMesh::VertexId, const GeVector &)
	Constrain movement of the vertex to the plane defined by the given normal.
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 &)
	Force the vertex to move with the specified velocity. This overrides any position constraints.
bool	subStepsDone () const
	Finer grained simulation control - allows the client more control over the computation. See step() for details.
void	preSubSteps ()
	Finer grained simulation control - allows the client more control over the computation. See step() for details.
void	subStep ()
	Finer grained simulation control - allows the client more control over the computation. See step() for details.
void	postSubSteps ()
	Finer grained simulation control - allows the client more control over the computation. See step() for details.
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 Methods
void	setupMass ()
	Fill the mass matrix (_M) using the initial mesh's triangles areas and the density parameter, as per [BarWit98] section 2.2.
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.

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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.

Test:

References:

• [BarWit98] D. Baraff and A. Witkin. Large Steps in Cloth Simulation. SIGGRAPH Conference Proceedings, 1998, 43-54. http://www-2.cs.cmu.edu/~baraff/papers/sig98.pdf
• [Pri02] D. Pritchard. "Implementing Baraff & Witkin's Cloth Simulation". Unpublished, 2002. http://freecloth.enigmati.ca/docs/report-chaps/
• [Mac00] D. Macri. Real-Time Cloth. Game Developers Conference, 2000. http://www.gdconf.com/archives/2000/macri.doc

Definition at line 106 of file simSimulator.h.

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The documentation for this class was generated from the following files:

• simSimulator.h
• simSimulator.cpp

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