goNUBS Class Reference

Cubic Non-uniform non-rational B-spline approximation. More...

#include <gonurbs.h>

Public Member Functions
	goNUBS (const goCurvef *curve)
	Constructor. More...
	goNUBS (const goCurved *curve)
	Constructor. More...
goDouble	getCurveLength () const
	Get curve length. More...
bool	calculate ()
	Calculate with current control points. More...
bool	setControlPoints (const goList< goPointf > &points)
	Calculate with given point list. More...
bool	setControlPoints (const goList< goPointd > &points)
bool	setControlPoints (goList< goPointf >::ConstElement *begin, goList< goPointf >::ConstElement *end, bool closed=false)
	Set control points to given point list. More...
bool	setControlPoints (goList< goPointd >::ConstElement *begin, goList< goPointd >::ConstElement *end, bool closed=false)
bool	setControlPoints (goList< goPointf >::ConstElement *begin, goIndex_t count, bool closed=false)
	Set control points to given point list. More...
bool	setControlPoints (goList< goPointd >::ConstElement *begin, goIndex_t count, bool closed=false)
	Set control points to given point list. More...
goPointf	operator() (goFloat u)
	Evaluate the B-spline curve at u. More...
	goNUBS (const goCurvef *curve)
	goNUBS (const goCurved *curve)
goDouble	getCurveLength () const
bool	calculate ()
bool	setControlPoints (const goList< goPointf > &points)
bool	setControlPoints (const goList< goPointd > &points)
bool	setControlPoints (goList< goPointf >::ConstElement *begin, goList< goPointf >::ConstElement *end, bool closed=false)
bool	setControlPoints (goList< goPointd >::ConstElement *begin, goList< goPointd >::ConstElement *end, bool closed=false)
bool	setControlPoints (goList< goPointf >::ConstElement *begin, goIndex_t count, bool closed=false)
bool	setControlPoints (goList< goPointd >::ConstElement *begin, goIndex_t count, bool closed=false)
goPointf	operator() (goFloat u)

Detailed Description

Cubic Non-uniform non-rational B-spline approximation.

Uses cubic NUBS to approximate a curve. A curve can either be given in the constructor as a goCurve* or as a goList<goPointf> to setControlPoints(). In order to get knots with multiplicity > 0, define points with the desired multiplicity. If you want periodic functions (closed curves), append the first point of the curve at its end. That's not tested, but should suffice.

Todo:

B is currently calculated recursively. Use de Boor instead.

Currently this class is not compiled. Replace the use of goPoint with goMath::Vector.

Author

Christian Gosch

Uses cubic NUBS to approximate a curve. A curve can either be given in the constructor as a goCurve* or as a goList<goPointf> to setControlPoints(). In order to get knots with multiplicity > 0, define points with the desired multiplicity. If you want periodic functions (closed curves), append the first point of the curve at its end. That's not tested, but should suffice.

Todo:

B is currently calculated recursively. Use de Boor instead.

Author

Christian Gosch

Constructor & Destructor Documentation

goNUBS() [1/2]

goNUBS::goNUBS

(

const goCurvef *

curve

)

Constructor.

Parameters

curve

Pointer to the curve object. If 0, no action is taken. If != 0, the curve is approximated and operator() can be used to evaluate the curve. The valid parameter range is [0,getCurveLength()).

goNUBS() [2/2]

goNUBS::goNUBS

(

const goCurved *

curve

)

Constructor.

Parameters

curve

Pointer to the curve object. If 0, no action is taken. If != 0, the curve is approximated and operator() can be used to evaluate the curve. The valid parameter range is [0,getCurveLength()).

Member Function Documentation

calculate()

bool goNUBS::calculate

(

)

Calculate with current control points.

Basically only calculates the knot values.

getCurveLength()

goDouble goNUBS::getCurveLength

(

)

const

Get curve length.

The valid parameter range for operator() can be determined with this function and is [0,getCurveLength()).

Returns

The curve length.

operator()()

goPointf goNUBS::operator()

(

goFloat

u

)

Evaluate the B-spline curve at u.

Note

Note that parameter u must be in a half-open interval. If you request nubs.operator()(nurbs.getCurveLength()), you will get (0,0,0) as an answer. E.g., nurbs.operator(nurbs.getCurveLength() - 1e-5) results in something close to the curve's end.

Todo:

If it nags someone too much, return the end point when nubs.operator()(nurbs.getCurveLength()) is requested.

Currently intervals are searched for linearly. Improve that when there's time.

Store the control points in an array additionally to speed up access.

Parameters

u	Point to evaluate at. Must be in [ 0,getCurveLength() ). Note the half-open interval.

Returns

Point at u. (0,0,0) by default, e.g. if u is out of range.

setControlPoints() [1/4]

bool goNUBS::setControlPoints

(

const goList< goPointf > &

points

)

Calculate with given point list.

Copies points to the internal point list, adds the last point twice and calls calculate().

Parameters

points

The point list describing the curve to be approximated.

Returns

True if successful, false otherwise.

setControlPoints() [2/4]

bool goNUBS::setControlPoints	(	goList< goPointd >::ConstElement *	begin,
		goIndex_t	count,
		bool	closed = false
	)

Set control points to given point list.

Copies points to the internal point list, adds the last point twice and calls calculate().

Parameters

points

The point list describing the curve to be approximated.

Returns

True if successful, false otherwise.

setControlPoints() [3/4]

bool goNUBS::setControlPoints	(	goList< goPointf >::ConstElement *	begin,
		goIndex_t	count,
		bool	closed = false
	)

Set control points to given point list.

Copies points to the internal point list, adds the last point twice and calls calculate().

Parameters

points

The point list describing the curve to be approximated.

Returns

True if successful, false otherwise.

setControlPoints() [4/4]

bool goNUBS::setControlPoints	(	goList< goPointf >::ConstElement *	begin,
		goList< goPointf >::ConstElement *	end,
		bool	closed = false
	)

Set control points to given point list.

Copies points to the internal point list, adds the last point twice and calls calculate().

Parameters

points

The point list describing the curve to be approximated.

Returns

True if successful, false otherwise.

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

• gonubs.h
• gonurbs.h
• gonubs.cpp