This reference page is linked to from the following overview topics: FBX SDK 2012, Supported Scene Elements, FBX Node Attributes, List of Python FBX classes.

Detailed Description

A Non-Uniform Rational B-Spline (NURBS) curve is a type of parametric geometry.

A NURBS curve is defined by the degree, form, knot vector and control points.

Let M be the degree of the curve. Let N be the number of control points of the curve.

The form of the curve can be open, closed or periodic. A curve with end points that do not meet is defined as an open curve. The number of knots in an open curve is defined as N+(M+1).

A closed curve simply has its last control point equal to its first control point. Note that this does not imply tangent continuity at the end point. The curve may have a kink at this point. In FBX the last control point is not specified by the user in the InitControlPoints() method. For example, if there are to be 10 control points in total, and the curve is to be closed, than only 9 control points need to be passed into the InitControlPoints() method. The last control point is implied to be equal to the first control point. Thus N represents the number of unique CVs.

A periodic curve has its last M control points equal to its first M control points. A periodic curve is tangent continuous at the ends. Similar to a closed curve, when creating a periodic curve, only the unique control points need to be set. For example a periodic curve of degree 3 with 10 control points requires only 7 CVs to be specified in the InitControlPoints() method. The last 3 CVs, which are the same as the first 3, are not included.

The calculation of the number of knots in closed and periodic curves is more complex. Since we have excluded one CV in N in a closed curve, the number of knots is N+(M+1)+1. Similarly, we excluded M CVs in periodic curves so the number of knots is N+(M+1)+M.

Note that FBX stores one extra knot at the beginning and and end of the knot vector, compared to some other graphics applications such as Maya. The two knots are not used in calculation, but they are included so that no data is lost when converting from file formats that do store the extra knots.

Definition at line 85 of file kfbxnurbscurve.h.

#include <kfbxnurbscurve.h>

Inheritance diagram for KFbxNurbsCurve:

[legend]

List of all members.

Public Types
enum	EDimension { e2D = 2, e3D, eDIMENSIONS_COUNT = 2 }
	The dimension of the CVs. More...
enum	EType { eOPEN, eCLOSED, ePERIODIC, eTYPE_COUNT }
	The curve's form. More...
enum	EError { eNurbCurveTypeUnknown, eWeightTooSmall, eKnotVectorError, eWrongNumberOfControlPoint, eErrorCount }
	Error identifiers. More...
Public Member Functions
virtual KFbxNodeAttribute::EAttributeType	GetAttributeType () const
	Returns the EAttributeType::eNURBS_CURVE node attribute type.
void	InitControlPoints (int pCount, EType pVType)
	Allocates memory space for the control points array as well as for the knot vector.
double *	GetKnotVector () const
	Returns the knot vector.
int	GetKnotCount () const
	Returns the number of elements in the knot vector.
void	SetOrder (int pOrder)
	Sets the order of the curve.
int	GetOrder () const
	Returns the NURBS curve order.
void	SetStep (int pStep)
	Sets the step of the curve.
int	GetStep () const
	Returns the NURBS curve step.
void	SetDimension (EDimension pDimension)
	Sets the dimension of the CVs.
EDimension	GetDimension () const
	Returns the control points dimension.
bool	IsRational ()
	Determines if the curve is rational or not.
int	GetSpanCount () const
	Calculates the number of curve spans with the following: Where S = Number of spans N = Number of CVs M = Order of the curve.
EType	GetType () const
	Returns NURBS type.
bool	IsPolyline () const
	Checks if the curve is a poly line.
bool	IsBezier () const
	This function determines if this NURBS curve is a Bezier curve.
int	TessellateCurve (KArrayTemplate< KFbxVector4 > &pPointArray, int pStep=16)
	Evaluate the point on the curve.
KFbxLine *	TessellateCurve (int pStep=16)
	Evaluate the point on the curve.
virtual KFbxObject &	Copy (const KFbxObject &pObject)
	Copy an object content into this object.
bool	FullMultiplicity () const
Public Attributes
bool	mIsRational
Protected Member Functions
	KFbxNurbsCurve (KFbxSdkManager &pManager, char const *pName)
void	Reset ()
virtual void	Destruct (bool pRecursive, bool pDependents)

e2D	Search for all occurrences
e3D	Search for all occurrences
eDIMENSIONS_COUNT	Search for all occurrences

eOPEN	Search for all occurrences
eCLOSED	Search for all occurrences
ePERIODIC	Search for all occurrences
eTYPE_COUNT	Search for all occurrences

eNurbCurveTypeUnknown	Search for all occurrences
eWeightTooSmall	Search for all occurrences
eKnotVectorError	Search for all occurrences
eWrongNumberOfControlPoint	Search for all occurrences
eErrorCount	Search for all occurrences

KFbxNurbsCurve	(	KFbxSdkManager &	pManager,
		char const *	pName
	)		`[protected]`

int TessellateCurve	(	KArrayTemplate< KFbxVector4 > &	pPointArray,
		int	pStep = `16`
	)

pPointArray	Save the evaluate result as a point array.
pStep	The evaluation frequency between two neighbor knots. Its default value is 16, which is same as Maya.

virtual void Destruct	(	bool	pRecursive,
		bool	pDependents
	)		`[protected, virtual]`

KFbxNurbsCurve Class Reference

Detailed Description

Public Types

Public Member Functions

Public Attributes

Protected Member Functions

Member Enumeration Documentation

Constructor & Destructor Documentation

Member Function Documentation

Member Data Documentation