MNurbsIntersector Class Reference

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Detailed Description

Nurbs intersector.

The MNurbsIntersector class contains methods for efficiently finding the closest point to a NURBS surface. A tree-based algorithm is used to find the closest point.

The create() method builds the internal data required for the algorithm. As a result, calls to it should be minimized as it is a heavy operation. If the NURBS surface or matrix changes, you will need to recreate the tree based data to correspond, again using the create() method.

This class is not threadsafe.

Examples:

closestPointOnNurbsSurfaceCmd.cpp, and intersectOnNurbsSurfaceCmd.cpp.

#include <MNurbsIntersector.h>

List of all members.

Public Member Functions
	MNurbsIntersector (void)
	Constructor.
virtual	~MNurbsIntersector (void)
	Destructor.
MStatus	create (MObject &nurbsObject, const MMatrix &matrix=MMatrix::identity)
	This method creates the data required by the intersector.
bool	isCreated (void)
	This method returns true if the intersector is created.
MStatus	getClosestPoint (MPoint &point, MPointOnNurbs &nurbsPoint, double maxDistance=DBL_MAX)
	This method finds the closest point.
MStatus	getIntersects (const MPoint &rayStartingPoint, const MVector &alongThisDirection, MDoubleArray &uArray, MDoubleArray &vArray, MPointArray &points, double tolerance)
	This method finds all the points of intersection of the NURBS surface with a ray (a vector at a point).
MStatus	getIntersect (const MPoint &rayStartingPoint, const MVector &alongThisDirection, double &u, double &v, MPoint &pntOfIntersection, double tolerance)
	This method finds the first point of intersection of the NURBS surface with a ray (a vector at a point).
Static Public Member Functions
static const char *	className ()
	Returns the name of this class.

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Member Function Documentation

MStatus create	(	MObject &	nurbsObject,
		const MMatrix &	matrix = MMatrix::identity
	)

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This method creates the data required by the intersector.

It is a heavy operation that should be called only when necessary, such as when the underlying NURBS surface or the matrix changes.

Parameters:

[in]	nurbsObject	a NURBS surface object .
[in]	matrix	specify the mapping to apply for transforming points that are specified in the getClosestPoint method into the object space of the NURBS surface.

Returns:

Status code

Status Codes:

• MS::kSuccess The NURBS intersector was created .
• MS::kInvalidParameter Object is not a kNurbsSurface, a kNurbsSurfaceData or a kNurbsSurfaceGeom.
• MS::kFailure Other internal failure .

Examples:

closestPointOnNurbsSurfaceCmd.cpp, and intersectOnNurbsSurfaceCmd.cpp.

bool isCreated

(

void

)

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This method returns true if the intersector is created.

False is returned otherwise.

MStatus getClosestPoint	(	MPoint &	point,
		MPointOnNurbs &	nurbsPoint,
		double	maxDistance = DBL_MAX
	)

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This method finds the closest point.

Information is returned in the nurbsPoint object.

Parameters:

[in]	point	Specifies the location for which to evaluate the closest point on the NURBS surface. `point' is transformed using the matrix parameter passed to the create() method, so for example if your matrix maps world to object space, then `point' should be specified in world space.
[out]	nurbsPoint	Resulting closest point in object space.
[in]	maxDistance	Maximum distance to consider in object space.

Returns:

Status code

Status Codes:

• MS::kSuccess The NURBS point was found.
• MS::kFailure object error, or create hasn't been called beforehand.

Examples:

closestPointOnNurbsSurfaceCmd.cpp.

MStatus getIntersects	(	const MPoint &	rayStartingPoint,
		const MVector &	alongThisDirection,
		MDoubleArray &	uArray,
		MDoubleArray &	vArray,
		MPointArray &	points,
		double	tolerance
	)

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This method finds all the points of intersection of the NURBS surface with a ray (a vector at a point).

The points are returned in the points object, and the U and V parameters of the points are returned in the uArray and vArray objects respectively.

Parameters:

[in]	rayStartingPoint	Starting location of ray to test
[in]	alongThisDirection	Direction of ray to test
[in]	uArray	U parameters of intersection (if any)
[in]	vArray	V parameters of intersection (if any)
[out]	points	Storage for points of intersection (if any)
[in]	tolerance	The epsilon value in the calculation

Returns:

Status code

Status Codes:

• MS::kSuccess An intersection point has been found
• MS::kFailure No intersection points found

MStatus getIntersect	(	const MPoint &	rayStartingPoint,
		const MVector &	alongThisDirection,
		double &	u,
		double &	v,
		MPoint &	pntOfIntersection,
		double	tolerance
	)

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This method finds the first point of intersection of the NURBS surface with a ray (a vector at a point).

The point is returned in the pntOfIntersection object, and the U and V parameters of the point are returned in the u and v variables respectively.

Parameters:

[in]	rayStartingPoint	Starting location of ray to test
[in]	alongThisDirection	Direction of ray to test
[in]	u	U parameter of intersection (if any)
[in]	v	V parameter of intersection (if any)
[out]	pntOfIntersection	Storage for closest point of intersection (if any)
[in]	tolerance	The epsilon value in the calculation

Returns:

Status code

Status Codes:

• MS::kSuccess An intersection point has been found
• MS::kFailure No intersection points found

Examples:

intersectOnNurbsSurfaceCmd.cpp.

const char * className

(

)

[static]

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Returns the name of this class.

Returns:

Name of this class.