Generic Bezier Curve Class allowing the user to generate basic curves using a number of different constriction methods, such as array of Vectors, array of numbers etc The class can automatically generate knot vectors as well or the user can specify their own. More...

#include <BezierCurve.h>

Collaboration diagram for ngl::BezierCurve:

Public Member Functions
	BezierCurve () noexcept
	default ctor sets initial values for Curve to be used with AddPoint , AddKnot etc More...

	BezierCurve (const Vec3 _p, unsigned int _nPoints, const Real _k, unsigned int _nKnots) noexcept
	Ctor passing in an Array of CP's and and Array of knots. More...

	BezierCurve (const Real *_p, unsigned int _nPoints) noexcept
	ctor passing in an array of points, note the knot vector will be automatically calculated as an open vector using a call to create knots More...

	BezierCurve (const BezierCurve &_c) noexcept
	copy ctor More...

	~BezierCurve () noexcept
	destructor More...

void	draw () const noexcept
	Draw method to draw the curve Note this will be slow as it calls the CoxDeBoor function to calculate each time it is much quicker to create a display list and use this. More...

void	drawControlPoints () const noexcept
	draw the control points More...

void	drawHull () const noexcept
	Draw the control hull. More...

Vec3	getPointOnCurve (Real _value) const noexcept
	get a point on the curve in the range of 0 - 1 based on the control points More...

void	addPoint (const Vec3 &_p) noexcept
	add a control point to the Curve More...

void	addPoint (Real _x, Real _y, Real _z) noexcept
	add a point to the curve using x,y,z values More...

void	addKnot (Real _k) noexcept
	add a knot value to the curve More...

void	createKnots () noexcept
	create a knot vector array based as an Open Vector (half 0.0 half 1.0) More...

Real	coxDeBoor (Real _u, unsigned int _i, unsigned int _k, const std::vector< Real > &_knots) const noexcept
	implementation of the CoxDeBoor algorithm for Bezier Curves borrowed from Rob Bateman's example and modified to make it work with the class. NOTE, this is a recursive function More...

void	setLOD (int _lod) noexcept
	set the Level of Detail for Drawing More...

void	createVAO () noexcept
	set the Level of Detail for Drawing More...

Protected Attributes
GLuint	m_listIndex
	the display list index created from glCreateLists More...

unsigned int	m_order
	The Order of the Curve = Degree +1. More...

unsigned int	m_lod
	The level of detail used to calculate how much detail to draw. More...

unsigned int	m_numCP
	The ammount of Control Points in the Curve. More...

unsigned int	m_degree
	The degree of the curve, Calculated from the Number of Control Points. More...

unsigned int	m_numKnots
	The knot vector always has as many values as the numer of verts (cp) + the degree. More...

std::vector< Vec3 >	m_cp
	the contol points for the curve More...

std::vector< Real >	m_knots
	the knot vector for the curve More...

AbstractVAO *	m_vaoCurve
	a vertex array object for our curve drawing More...

AbstractVAO *	m_vaoPoints
	a vertex array object for our point drawing More...

Detailed Description

Generic Bezier Curve Class allowing the user to generate basic curves using a number of different constriction methods, such as array of Vectors, array of numbers etc The class can automatically generate knot vectors as well or the user can specify their own.

Author: Rob Bateman modified and augmented by Jonathan Macey

Version: 3.0

Date: Last Revision 27/09/09 Updated to NCCA Coding standard and V2.0 History : /06/08 Initial class written

Todo:: update this class to run the CoxDeBoor algo once and then store the points in a dynamic array based on the LOD value passed in. This will speed up the execution for static curves as at present we calculate each time. Also this array can then be used to draw with VertexArrays and we will not need to create the DisplayLists

Definition at line 45 of file BezierCurve.h.

Constructor & Destructor Documentation

ngl::BezierCurve::BezierCurve ( )

noexcept

default ctor sets initial values for Curve to be used with AddPoint , AddKnot etc

Definition at line 26 of file BezierCurve.cpp.

References m_degree, m_listIndex, m_lod, m_numCP, m_numKnots, m_order, m_vaoCurve, and m_vaoPoints.

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ngl::BezierCurve::BezierCurve	(	const Vec3 *	_p,
		unsigned int	_nPoints,
		const Real *	_k,
		unsigned int	_nKnots
	)

noexcept

Ctor passing in an Array of CP's and and Array of knots.

Parameters

[in]	_p	an array of Vector objects which are the control
[in]	_nPoints	the size of the Point Array
[in]	_k	and array of knot values
[in]	_nKnots	the size of the knot array

ngl::BezierCurve::BezierCurve	(	const Real *	_p,
		unsigned int	_nPoints
	)

noexcept

ctor passing in an array of points, note the knot vector will be automatically calculated as an open vector using a call to create knots

Parameters

[in]	_p	the array of CP values expressed as groups of 3 float x,y,z values
[in]	_nPoints	the size of the array *p (note this is the total size of the array)

ngl::BezierCurve::BezierCurve ( const BezierCurve & _c )

noexcept

copy ctor

Parameters

_c	the curve to copy

Definition at line 47 of file BezierCurve.cpp.

References BezierCurve(), createKnots(), m_cp, m_degree, m_knots, m_lod, m_numCP, m_numKnots, m_order, m_vaoCurve, and m_vaoPoints.

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ngl::BezierCurve::~BezierCurve ( )

noexcept

destructor

Definition at line 100 of file BezierCurve.cpp.

References m_cp, m_knots, m_vaoCurve, m_vaoPoints, ngl::AbstractVAO::removeVAO(), and ngl::AbstractVAO::unbind().

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Member Function Documentation

void ngl::BezierCurve::addKnot ( Real _k )

noexcept

add a knot value to the curve

Parameters

[in] _k the value of the knot (note this is added to the end of the curve

Definition at line 220 of file BezierCurve.cpp.

References m_knots, m_numCP, m_numKnots, and m_order.

void ngl::BezierCurve::addPoint ( const Vec3 & _p )

noexcept

add a control point to the Curve

Parameters

[in] &_p the point to add

Definition at line 194 of file BezierCurve.cpp.

References m_cp, m_degree, m_numCP, m_numKnots, and m_order.

void ngl::BezierCurve::addPoint	(	Real	_x,
		Real	_y,
		Real	_z
	)

noexcept

add a point to the curve using x,y,z values

Parameters

[in]	_x	x value of point
[in]	_y	y value of point
[in]	_z	z value of point

Definition at line 207 of file BezierCurve.cpp.

References m_cp, m_degree, m_numCP, m_numKnots, and m_order.

Real ngl::BezierCurve::coxDeBoor	(	Real	_u,
		unsigned int	_i,
		unsigned int	_k,
		const std::vector< Real > &	_knots
	)		const

noexcept

implementation of the CoxDeBoor algorithm for Bezier Curves borrowed from Rob Bateman's example and modified to make it work with the class. NOTE, this is a recursive function

Returns: Real the evaluation of the weight at the current value

Parameters

[in]	_u
[in]	_i
[in]	_k
[in]	_knots	the array of knots for the curve

Definition at line 114 of file BezierCurve.cpp.

References coxDeBoor().

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void ngl::BezierCurve::createKnots ( )

noexcept

create a knot vector array based as an Open Vector (half 0.0 half 1.0)

Definition at line 38 of file BezierCurve.cpp.

References m_knots, and m_numKnots.

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void ngl::BezierCurve::createVAO ( )

noexcept

set the Level of Detail for Drawing

Definition at line 226 of file BezierCurve.cpp.

References ngl::AbstractVAO::bind(), ngl::VAOFactory::createVAO(), getPointOnCurve(), GL_FLOAT, GL_LINE_STRIP, GL_POINTS, m_cp, m_knots, m_lod, m_numCP, m_numKnots, m_vaoCurve, m_vaoPoints, ngl::AbstractVAO::removeVAO(), ngl::AbstractVAO::setData(), ngl::AbstractVAO::setNumIndices(), ngl::AbstractVAO::setVertexAttributePointer(), and ngl::AbstractVAO::unbind().

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void ngl::BezierCurve::draw ( ) const

noexcept

Draw method to draw the curve Note this will be slow as it calls the CoxDeBoor function to calculate each time it is much quicker to create a display list and use this.

Todo:: Modify this to use faster method than display lists

Definition at line 160 of file BezierCurve.cpp.

References ngl::AbstractVAO::bind(), ngl::AbstractVAO::draw(), m_vaoCurve, and ngl::AbstractVAO::unbind().

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void ngl::BezierCurve::drawControlPoints ( ) const

noexcept

draw the control points

Definition at line 140 of file BezierCurve.cpp.

References ngl::AbstractVAO::bind(), ngl::AbstractVAO::draw(), GL_POINTS, m_vaoPoints, ngl::AbstractVAO::setMode(), and ngl::AbstractVAO::unbind().

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void ngl::BezierCurve::drawHull ( ) const

noexcept

Draw the control hull.

Definition at line 151 of file BezierCurve.cpp.

References ngl::AbstractVAO::bind(), ngl::AbstractVAO::draw(), GL_LINE_STRIP, m_vaoPoints, ngl::AbstractVAO::setMode(), and ngl::AbstractVAO::unbind().

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Vec3 ngl::BezierCurve::getPointOnCurve ( Real _value ) const

noexcept

get a point on the curve in the range of 0 - 1 based on the control points

Parameters

[in] _value the point to evaluate between 0 and 1

Returns: the value of the point at t

Definition at line 168 of file BezierCurve.cpp.

References coxDeBoor(), m_cp, m_degree, m_knots, and m_numCP.

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void ngl::BezierCurve::setLOD ( int _lod )

inlinenoexcept

set the Level of Detail for Drawing

Note: this will have no Effect if the createVAO has been called before

Parameters

[in] _lod the level of detail to use when creating the display list for drawing the higher the number the finer the drawing

Definition at line 138 of file BezierCurve.h.

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Member Data Documentation

std::vector<Vec3> ngl::BezierCurve::m_cp

protected

the contol points for the curve

Definition at line 172 of file BezierCurve.h.

unsigned int ngl::BezierCurve::m_degree

protected

The degree of the curve, Calculated from the Number of Control Points.

Definition at line 164 of file BezierCurve.h.

std::vector<Real> ngl::BezierCurve::m_knots

protected

the knot vector for the curve

Definition at line 176 of file BezierCurve.h.

GLuint ngl::BezierCurve::m_listIndex

protected

the display list index created from glCreateLists

Definition at line 148 of file BezierCurve.h.

unsigned int ngl::BezierCurve::m_lod

protected

The level of detail used to calculate how much detail to draw.

Definition at line 156 of file BezierCurve.h.

unsigned int ngl::BezierCurve::m_numCP

protected

The ammount of Control Points in the Curve.

Definition at line 160 of file BezierCurve.h.

unsigned int ngl::BezierCurve::m_numKnots

protected

The knot vector always has as many values as the numer of verts (cp) + the degree.

Definition at line 168 of file BezierCurve.h.

unsigned int ngl::BezierCurve::m_order

protected

The Order of the Curve = Degree +1.

Definition at line 152 of file BezierCurve.h.

AbstractVAO* ngl::BezierCurve::m_vaoCurve

protected

a vertex array object for our curve drawing

Definition at line 180 of file BezierCurve.h.

AbstractVAO* ngl::BezierCurve::m_vaoPoints

protected

a vertex array object for our point drawing

Definition at line 184 of file BezierCurve.h.

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

Public Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation