distance_constraint Class Reference

List of all members.

Public Members
		distance_constraint ( const double u, const double d )
		The only constructur for a `distance_constraint.` More...
	virtual	~distance_constraint (void)
	virtual void	energy ( const double tol, const vector< vector2 > &p, double &e, vector< vector2 > &dedp ) const
		Calculate a dimensionless measure of the potential energy (e) of the `constraint.` More...
	double	wanted_distance (void) const
		Get the wanted distance between the two points. More...
	void	wanted_distance ( const double d )
		Change the wanted distance between the two points. More...
Friends
	void	assoc ( distance_constraint &c, vector2 &p0, vector2 &p1 )
		Associates a `distance_constraint` with the 2 points it constrains. More...
	void	unassoc ( distance_constraint &c )
		Disassociates a `distance_constraint` from the points it constrains. More...

Detailed Description

Constrain the distance between two points.

Definition at line 39 of file distance_constraint.h.

Member Function Documentation

distance_constraint::distance_constraint (const double u, const double d)

The only constructur for a distance_constraint.

Parameters:

u	the degree of uncertainty of the constriant.
d	the distance to which the points should be constrained.

Preconditions:

 assert( 0.0 < u ).
 assert( 0.0 <= d );

Postconditions:

 assert( this->uncertainty() == u );
 assert( this->wanted_distance() == d );
 assert( this->points().size() == 2 );
 assert( this->points()[0] == 0 );
 assert( this->points()[1] == 0 );

Invariants:

 assert( !this->points()[0] || !this->points()[1] ||
    this->energy() == pow(
       (this->distance() - this->wanted_distance())/this->uncertainty(),
       2 ) );

Definition at line 37 of file distance_constraint.cpp.

distance_constraint::~distance_constraint (void) [virtual]

Definition at line 63 of file distance_constraint.cpp.

void distance_constraint::energy (const double tol, const vector<vector2>& p, double & e, vector<vector2>& dedp) const [virtual]

Calculate a dimensionless measure of the potential energy (e) of the constraint.

This is equivalent to a measure of how poorly the constraint is satisfied. If *(this->points()[i]) had position p[i], it calculates the energy (e) and the rates of change of that energy (dedp) with respect to the point positions. Larger values indicate the constraint is less well satisfied. 0 is the minimum possible energy, and energy <= 1 indicates that the constraint is satisifed to within the uncertainty of the constraint.

Parameters:

tol	is a dimensionless calculation tolerance.
p	are the point positions.

Return values:

e	the energy.
dedp	is the rate of change of energy with position.

Preconditions:

 assert( p.size() == 2 );
 assert( 0 < tol && tol < 1 );

Postconditions:

 assert( dedp.size() == 2 );

Reimplemented from constraint.

Definition at line 70 of file distance_constraint.cpp.

double distance_constraint::wanted_distance (void) const [inline]

Get the wanted distance between the two points.

The expected distance from points()[0] to points()[1].

Returns:: The wanted distance.

Definition at line 166 of file distance_constraint.h.

void distance_constraint::wanted_distance (const double d)

Change the wanted distance between the two points.

Parameters:

the

new wanted distance.

Preconditions:

 assert( 0.0 <= d );

Postconditions:

 assert( this->wanted_distance() == d );

Definition at line 115 of file distance_constraint.cpp.

Friends And Related Function Documentation

void assoc (distance_constraint & c, vector2 & p0, vector2 & p1) [friend]

Associates a distance_constraint with the 2 points it constrains.

Preconditions:

 assert( !c.points()[0] );
 assert( !c.points()[1] );

Postconditions:

 assert( c.points()[0] == &p0 );
 assert( c.points()[1] == &p1 );

Definition at line 119 of file distance_constraint.h.

void unassoc (distance_constraint & c) [friend]

Disassociates a distance_constraint from the points it constrains.

Postconditions:

 assert( !c.points()[0] );
 assert( !c.points()[1] );

Definition at line 139 of file distance_constraint.h.

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

Generated at Sun Jul 14 20:38:18 2002 for Mapper by

distance_constraint Class Reference

Public Members

Friends

Detailed Description

Member Function Documentation

Friends And Related Function Documentation