KFbxNurbsCurve Class Reference
#include
<kfbxnurbscurve.h>
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 86 of file kfbxnurbscurve.h.
Public Types |
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| enum | EDimension |
The dimension of the CVs
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| enum | EType |
The form of the curve
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| enum | EError |
| Error identifiers. More... |
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Public Member Functions |
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virtual KFbxNodeAttribute::EAttributeType |
GetAttributeType () const |
| Return the type of node attribute. |
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| void | InitControlPoints (int pCount, EType pVType) |
| Allocate memory space for the array of
control points as well as the knot vector. |
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| double * | GetKnotVector () const |
| Get knot vector. |
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| int | GetKnotCount () const |
| Get the number of elements in the knot
vector. |
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| int | GetOrder () const |
| Get nurb curve order. |
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| void | SetDimension (EDimension pDimension) |
| Sets the dimension of the CVs For 3D curves:
control point = ( x, y, z, w ), where w is the weight For 2D
curves: control point = ( x, y, 0, w ), where the z component is
unused, and w is the weight. |
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| EDimension | GetDimension () const |
| Gets the dimension of the control points.
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| bool | IsRational () |
| Determines if the curve is rational or not.
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| int | GetSpanCount () |
| Calculates the number of spans in the curve
using the following: Where S = Number of spans N = Number of CVs M
= Order of the curve. |
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| EType | GetType () const |
| Get nurb type. |
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| bool | IsPolyline () const |
| Checks if the curve is a poly line. |
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| bool | IsBezier () |
| Bezier curves are a special case of nurbs
curve. |
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| virtual KFbxObject * | Clone (KFbxObject *pContainer, KFbxObject::ECloneType pCloneType=eDEEP_CLONE) const |
| Creates a clone of this object. |
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Protected Member Functions |
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| KFbxNurbsCurve & | operator= (KFbxNurbsCurve const &pNurb) |
| Assignment operator. |
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Member Enumeration Documentation
| enum EDimension |
The dimension of the CVs
- e2D The CVs are two dimensional points
- e3D The CVs are three dimensional points.
Definition at line 97 of file kfbxnurbscurve.h.
| enum EType |
| enum EError |
Error identifiers.
- eINDEX_OUT_OF_RANGE
- eNULL_PARAMETER
- eMATERIAL_NOT_FOUND
- eMATERIAL_ALREADY_ADDED
- eTEXTURE_NOT_FOUND
- eTEXTURE_ALREADY_ADDED
- eSHAPE_ALREADY_ADDED
- eSHAPE_INVALID_NAME
- eSHAPE_NAME_CLASH
- eSHAPE_NO_CURVE_FOUND
- eUNKNOWN_ERROR
Reimplemented from KFbxGeometry.
Definition at line 215 of file kfbxnurbscurve.h.
Member Function Documentation
| virtual KFbxNodeAttribute::EAttributeType GetAttributeType | ( | ) | const [virtual] |
| void InitControlPoints | ( | int | pCount, | |
| EType | pVType | |||
| ) |
Allocate memory space for the array of control points as well as the knot vector.
- Parameters:
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pCount Number of control points. pVType Nurb type in V direction.
- Remarks:
- This function should always be called after KFbxNurb::SetOrder().
| double* GetKnotVector | ( | ) | const [inline] |
Get knot vector.
- Returns:
- Pointer to the array of knots.
Definition at line 128 of file kfbxnurbscurve.h.
| int GetKnotCount | ( | ) | const |
Get the number of elements in the knot vector.
- Returns:
- The number of knots. See KFbxNurbsCurve description for more details.
| int GetOrder | ( | ) | const [inline] |
| void SetDimension | ( | EDimension | pDimension | ) | [inline] |
Sets the dimension of the CVs For 3D curves: control point = ( x, y, z, w ), where w is the weight For 2D curves: control point = ( x, y, 0, w ), where the z component is unused, and w is the weight.
- Parameters:
-
pDimension - the dimension of the control points. (3d or 2d)
Definition at line 149 of file kfbxnurbscurve.h.
| EDimension GetDimension | ( | ) | const [inline] |
Gets the dimension of the control points.
- Returns:
- The dimension of the curve
Definition at line 154 of file kfbxnurbscurve.h.
| bool IsRational | ( | ) |
Determines if the curve is rational or not.
- Returns:
- True if the curve is rational, false otherwise
| int GetSpanCount | ( | ) |
Calculates the number of spans in the curve using the following: Where S = Number of spans N = Number of CVs M = Order of the curve.
S = N - M + 1;
In this calculation N includes the duplicate CVs for closed and periodic curves.
- Returns:
- The number of spans if the curve has been initialized, -1 otherwise.
| EType GetType | ( | ) | const [inline] |
Get nurb type.
- Returns:
- Nurb curve type identifier.
Definition at line 180 of file kfbxnurbscurve.h.
| bool IsPolyline | ( | ) | const [inline] |
Checks if the curve is a poly line.
(A poly line is a linear nurbs curve )
- Returns:
trueif curve is a poly line, false otherwise.
Definition at line 187 of file kfbxnurbscurve.h.
| bool IsBezier | ( | ) |
Bezier curves are a special case of nurbs curve.
This function determines if this nurbs curve is a Bezier curve.
- Returns:
trueif curve is a Bezier curve, false otherwise.
| virtual KFbxObject* Clone | ( | KFbxObject * | pContainer, | |
| KFbxObject::ECloneType | pCloneType =
eDEEP_CLONE |
|||
| ) | const [virtual] |
Creates a clone of this object.
- Parameters:
-
pContainer The object, typically a document or a scene, that contains the new clone(can be NULL). pCloneType The type of clone to be created.
- Returns:
- The new clone, or NULL (if the specified clone type is not supported).
Reimplemented from KFbxGeometry.
| KFbxNurbsCurve& operator= | ( | KFbxNurbsCurve const & | pNurb | ) | [protected] |
Assignment operator.
- Parameters:
-
pNurb KFbxNurbsCurve object assigned to this one.