Generate a surface covered with randomly placed hills. More...

#include <vtkParametricRandomHills.h>

Inheritance diagram for vtkParametricRandomHills:

Collaboration diagram for vtkParametricRandomHills:

Public Types
typedef vtkParametricFunction	Superclass

Public Types inherited from vtkParametricFunction
typedef vtkObject	Superclass

Public Member Functions
virtual vtkTypeBool	IsA (const char *type)
	Return 1 if this class is the same type of (or a subclass of) the named class. More...

vtkParametricRandomHills *	NewInstance () const

void	PrintSelf (ostream &os, vtkIndent indent) override
	Methods invoked by print to print information about the object including superclasses. More...

int	GetDimension () override
	Return the parametric dimension of the class. More...

void	Evaluate (double uvw[3], double Pt[3], double Duvw[9]) override
	Construct a terrain consisting of hills on a surface. More...

double	EvaluateScalar (double uvw[3], double Pt[3], double Duvw[9]) override
	Calculate a user defined scalar using one or all of uvw, Pt, Duvw. More...


virtual void	SetNumberOfHills (int)
	Set/Get the number of hills. More...

virtual int	GetNumberOfHills ()
	Set/Get the number of hills. More...


virtual void	SetHillXVariance (double)
	Set/Get the hill variance in the x-direction. More...

virtual double	GetHillXVariance ()
	Set/Get the hill variance in the x-direction. More...


virtual void	SetHillYVariance (double)
	Set/Get the hill variance in the y-direction. More...

virtual double	GetHillYVariance ()
	Set/Get the hill variance in the y-direction. More...


virtual void	SetHillAmplitude (double)
	Set/Get the hill amplitude (height). More...

virtual double	GetHillAmplitude ()
	Set/Get the hill amplitude (height). More...


virtual void	SetRandomSeed (int)
	Set/Get the Seed for the random number generator, a value of 1 will initialize the random number generator, a negative value will initialize it with the system time. More...

virtual int	GetRandomSeed ()
	Set/Get the Seed for the random number generator, a value of 1 will initialize the random number generator, a negative value will initialize it with the system time. More...


virtual void	SetAllowRandomGeneration (vtkTypeBool)
	Set/Get the random generation flag. More...

virtual vtkTypeBool	GetAllowRandomGeneration ()
	Set/Get the random generation flag. More...

virtual void	AllowRandomGenerationOn ()
	Set/Get the random generation flag. More...

virtual void	AllowRandomGenerationOff ()
	Set/Get the random generation flag. More...


virtual void	SetXVarianceScaleFactor (double)
	Set/Get the scaling factor for the variance in the x-direction. More...

virtual double	GetXVarianceScaleFactor ()
	Set/Get the scaling factor for the variance in the x-direction. More...


virtual void	SetYVarianceScaleFactor (double)
	Set/Get the scaling factor for the variance in the y-direction. More...

virtual double	GetYVarianceScaleFactor ()
	Set/Get the scaling factor for the variance in the y-direction. More...


virtual void	SetAmplitudeScaleFactor (double)
	Set/Get the scaling factor for the amplitude. More...

virtual double	GetAmplitudeScaleFactor ()
	Set/Get the scaling factor for the amplitude. More...

Public Member Functions inherited from vtkParametricFunction
vtkParametricFunction *	NewInstance () const

virtual void	SetMinimumU (double)
	Set/Get the minimum u-value. More...

virtual double	GetMinimumU ()
	Set/Get the minimum u-value. More...

virtual void	SetMaximumU (double)
	Set/Get the maximum u-value. More...

virtual double	GetMaximumU ()
	Set/Get the maximum u-value. More...

virtual void	SetMinimumV (double)
	Set/Get the minimum v-value. More...

virtual double	GetMinimumV ()
	Set/Get the minimum v-value. More...

virtual void	SetMaximumV (double)
	Set/Get the maximum v-value. More...

virtual double	GetMaximumV ()
	Set/Get the maximum v-value. More...

virtual void	SetMinimumW (double)
	Set/Get the minimum w-value. More...

virtual double	GetMinimumW ()
	Set/Get the minimum w-value. More...

virtual void	SetMaximumW (double)
	Set/Get the maximum w-value. More...

virtual double	GetMaximumW ()
	Set/Get the maximum w-value. More...

virtual void	SetJoinU (vtkTypeBool)
	Set/Get the flag which joins the first triangle strip to the last one. More...

virtual vtkTypeBool	GetJoinU ()
	Set/Get the flag which joins the first triangle strip to the last one. More...

virtual void	JoinUOn ()
	Set/Get the flag which joins the first triangle strip to the last one. More...

virtual void	JoinUOff ()
	Set/Get the flag which joins the first triangle strip to the last one. More...

virtual void	SetJoinV (vtkTypeBool)
	Set/Get the flag which joins the ends of the triangle strips. More...

virtual vtkTypeBool	GetJoinV ()
	Set/Get the flag which joins the ends of the triangle strips. More...

virtual void	JoinVOn ()
	Set/Get the flag which joins the ends of the triangle strips. More...

virtual void	JoinVOff ()
	Set/Get the flag which joins the ends of the triangle strips. More...

virtual void	SetJoinW (vtkTypeBool)
	Set/Get the flag which joins the ends of the triangle strips. More...

virtual vtkTypeBool	GetJoinW ()
	Set/Get the flag which joins the ends of the triangle strips. More...

virtual void	JoinWOn ()
	Set/Get the flag which joins the ends of the triangle strips. More...

virtual void	JoinWOff ()
	Set/Get the flag which joins the ends of the triangle strips. More...

virtual void	SetTwistU (vtkTypeBool)
	Set/Get the flag which joins the first triangle strip to the last one with a twist. More...

virtual vtkTypeBool	GetTwistU ()
	Set/Get the flag which joins the first triangle strip to the last one with a twist. More...

virtual void	TwistUOn ()
	Set/Get the flag which joins the first triangle strip to the last one with a twist. More...

virtual void	TwistUOff ()
	Set/Get the flag which joins the first triangle strip to the last one with a twist. More...

virtual void	SetTwistV (vtkTypeBool)
	Set/Get the flag which joins the ends of the triangle strips with a twist. More...

virtual vtkTypeBool	GetTwistV ()
	Set/Get the flag which joins the ends of the triangle strips with a twist. More...

virtual void	TwistVOn ()
	Set/Get the flag which joins the ends of the triangle strips with a twist. More...

virtual void	TwistVOff ()
	Set/Get the flag which joins the ends of the triangle strips with a twist. More...

virtual void	SetTwistW (vtkTypeBool)
	Set/Get the flag which joins the ends of the triangle strips with a twist. More...

virtual vtkTypeBool	GetTwistW ()
	Set/Get the flag which joins the ends of the triangle strips with a twist. More...

virtual void	TwistWOn ()
	Set/Get the flag which joins the ends of the triangle strips with a twist. More...

virtual void	TwistWOff ()
	Set/Get the flag which joins the ends of the triangle strips with a twist. More...

virtual void	SetClockwiseOrdering (vtkTypeBool)
	Set/Get the flag which determines the ordering of the vertices forming the triangle strips. More...

virtual vtkTypeBool	GetClockwiseOrdering ()
	Set/Get the flag which determines the ordering of the vertices forming the triangle strips. More...

virtual void	ClockwiseOrderingOn ()
	Set/Get the flag which determines the ordering of the vertices forming the triangle strips. More...

virtual void	ClockwiseOrderingOff ()
	Set/Get the flag which determines the ordering of the vertices forming the triangle strips. More...

virtual void	SetDerivativesAvailable (vtkTypeBool)
	Set/Get the flag which determines whether derivatives are available from the parametric function (i.e., whether the Evaluate() method returns valid derivatives). More...

virtual vtkTypeBool	GetDerivativesAvailable ()
	Set/Get the flag which determines whether derivatives are available from the parametric function (i.e., whether the Evaluate() method returns valid derivatives). More...

virtual void	DerivativesAvailableOn ()
	Set/Get the flag which determines whether derivatives are available from the parametric function (i.e., whether the Evaluate() method returns valid derivatives). More...

virtual void	DerivativesAvailableOff ()
	Set/Get the flag which determines whether derivatives are available from the parametric function (i.e., whether the Evaluate() method returns valid derivatives). More...

Public Member Functions inherited from vtkObject
	vtkBaseTypeMacro (vtkObject, vtkObjectBase)

virtual void	DebugOn ()
	Turn debugging output on. More...

virtual void	DebugOff ()
	Turn debugging output off. More...

bool	GetDebug ()
	Get the value of the debug flag. More...

void	SetDebug (bool debugFlag)
	Set the value of the debug flag. More...

virtual void	Modified ()
	Update the modification time for this object. More...

virtual vtkMTimeType	GetMTime ()
	Return this object's modified time. More...

void	PrintSelf (ostream &os, vtkIndent indent) override
	Methods invoked by print to print information about the object including superclasses. More...

void	RemoveObserver (unsigned long tag)

void	RemoveObservers (unsigned long event)

void	RemoveObservers (const char *event)

void	RemoveAllObservers ()

vtkTypeBool	HasObserver (unsigned long event)

vtkTypeBool	HasObserver (const char *event)

int	InvokeEvent (unsigned long event)

int	InvokeEvent (const char *event)

unsigned long	AddObserver (unsigned long event, vtkCommand *, float priority=0.0f)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

unsigned long	AddObserver (const char event, vtkCommand , float priority=0.0f)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

vtkCommand *	GetCommand (unsigned long tag)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

void	RemoveObserver (vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

void	RemoveObservers (unsigned long event, vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

void	RemoveObservers (const char event, vtkCommand )
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

vtkTypeBool	HasObserver (unsigned long event, vtkCommand *)
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

vtkTypeBool	HasObserver (const char event, vtkCommand )
	Allow people to add/remove/invoke observers (callbacks) to any VTK object. More...

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::*callback)(), float priority=0.0f)
	Overloads to AddObserver that allow developers to add class member functions as callbacks for events. More...

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, void(T::callback)(vtkObject , unsigned long, void *), float priority=0.0f)
	Overloads to AddObserver that allow developers to add class member functions as callbacks for events. More...

template<class U , class T >
unsigned long	AddObserver (unsigned long event, U observer, bool(T::callback)(vtkObject , unsigned long, void *), float priority=0.0f)
	Allow user to set the AbortFlagOn() with the return value of the callback method. More...

int	InvokeEvent (unsigned long event, void *callData)
	This method invokes an event and return whether the event was aborted or not. More...

int	InvokeEvent (const char event, void callData)
	This method invokes an event and return whether the event was aborted or not. More...

Public Member Functions inherited from vtkObjectBase
const char *	GetClassName () const
	Return the class name as a string. More...

virtual void	Delete ()
	Delete a VTK object. More...

virtual void	FastDelete ()
	Delete a reference to this object. More...

void	InitializeObjectBase ()

void	Print (ostream &os)
	Print an object to an ostream. More...

virtual void	Register (vtkObjectBase *o)
	Increase the reference count (mark as used by another object). More...

virtual void	UnRegister (vtkObjectBase *o)
	Decrease the reference count (release by another object). More...

int	GetReferenceCount ()
	Return the current reference count of this object. More...

void	SetReferenceCount (int)
	Sets the reference count. More...

void	PrintRevisions (ostream &)
	Legacy. More...

virtual void	PrintHeader (ostream &os, vtkIndent indent)
	Methods invoked by print to print information about the object including superclasses. More...

virtual void	PrintTrailer (ostream &os, vtkIndent indent)
	Methods invoked by print to print information about the object including superclasses. More...

Static Public Member Functions
static vtkTypeBool	IsTypeOf (const char *type)

static vtkParametricRandomHills *	SafeDownCast (vtkObjectBase *o)

static vtkParametricRandomHills *	New ()
	Construct a surface of random hills with the following parameters: MinimumU = -10, MaximumU = 10, MinimumV = -10, MaximumV = 10, JoinU = 0, JoinV = 0, TwistU = 0, TwistV = 0; ClockwiseOrdering = 0, DerivativesAvailable = 0, Number of hills = 30, Variance of the hills 2.5 in both x- and y- directions, Scaling factor for the variances 1/3 in both x- and y- directions, Amplitude of each hill = 2, Scaling factor for the amplitude = 1/3, RandomSeed = 1, AllowRandomGeneration = 1. More...

Static Public Member Functions inherited from vtkParametricFunction
static vtkTypeBool	IsTypeOf (const char *type)

static vtkParametricFunction *	SafeDownCast (vtkObjectBase *o)

Static Public Member Functions inherited from vtkObject
static vtkObject *	New ()
	Create an object with Debug turned off, modified time initialized to zero, and reference counting on. More...

static void	BreakOnError ()
	This method is called when vtkErrorMacro executes. More...

static void	SetGlobalWarningDisplay (int val)
	This is a global flag that controls whether any debug, warning or error messages are displayed. More...

static void	GlobalWarningDisplayOn ()
	This is a global flag that controls whether any debug, warning or error messages are displayed. More...

static void	GlobalWarningDisplayOff ()
	This is a global flag that controls whether any debug, warning or error messages are displayed. More...

static int	GetGlobalWarningDisplay ()
	This is a global flag that controls whether any debug, warning or error messages are displayed. More...

Static Public Member Functions inherited from vtkObjectBase
static vtkTypeBool	IsTypeOf (const char *name)
	Return 1 if this class type is the same type of (or a subclass of) the named class. More...

static vtkObjectBase *	New ()
	Create an object with Debug turned off, modified time initialized to zero, and reference counting on. More...

Protected Member Functions
virtual vtkObjectBase *	NewInstanceInternal () const

	vtkParametricRandomHills ()

	~vtkParametricRandomHills () override

Protected Member Functions inherited from vtkParametricFunction
	vtkParametricFunction ()

	~vtkParametricFunction () override

Protected Member Functions inherited from vtkObject
	vtkObject ()

	~vtkObject () override

void	RegisterInternal (vtkObjectBase *, vtkTypeBool check) override

void	UnRegisterInternal (vtkObjectBase *, vtkTypeBool check) override

void	InternalGrabFocus (vtkCommand mouseEvents, vtkCommand keypressEvents=nullptr)
	These methods allow a command to exclusively grab all events. More...

void	InternalReleaseFocus ()
	These methods allow a command to exclusively grab all events. More...

Protected Member Functions inherited from vtkObjectBase
	vtkObjectBase ()

virtual	~vtkObjectBase ()

virtual void	CollectRevisions (ostream &)

virtual void	ReportReferences (vtkGarbageCollector *)

	vtkObjectBase (const vtkObjectBase &)

void	operator= (const vtkObjectBase &)

Protected Attributes
int	NumberOfHills

double	HillXVariance

double	HillYVariance

double	HillAmplitude

int	RandomSeed

double	XVarianceScaleFactor

double	YVarianceScaleFactor

double	AmplitudeScaleFactor

vtkTypeBool	AllowRandomGeneration

int	previousNumberOfHills

double	previousHillXVariance

double	previousHillYVariance

double	previousHillAmplitude

int	previousRandomSeed

double	previousXVarianceScaleFactor

double	previousYVarianceScaleFactor

double	previousAmplitudeScaleFactor

int	previousAllowRandomGeneration

Protected Attributes inherited from vtkParametricFunction
double	MinimumU

double	MaximumU

double	MinimumV

double	MaximumV

double	MinimumW

double	MaximumW

vtkTypeBool	JoinU

vtkTypeBool	JoinV

vtkTypeBool	JoinW

vtkTypeBool	TwistU

vtkTypeBool	TwistV

vtkTypeBool	TwistW

vtkTypeBool	ClockwiseOrdering

vtkTypeBool	DerivativesAvailable

Protected Attributes inherited from vtkObject
bool	Debug

vtkTimeStamp	MTime

vtkSubjectHelper *	SubjectHelper

Protected Attributes inherited from vtkObjectBase
vtkAtomicInt32	ReferenceCount

vtkWeakPointerBase **	WeakPointers

Detailed Description

Generate a surface covered with randomly placed hills.

vtkParametricRandomHills generates a surface covered with randomly placed hills. Hills will vary in shape and height since the presence of nearby hills will contribute to the shape and height of a given hill. An option is provided for placing hills on a regular grid on the surface. In this case the hills will all have the same shape and height.

For further information about this surface, please consult the technical description "Parametric surfaces" in http://www.vtk.org/publications in the "VTK Technical Documents" section in the VTk.org web pages.

Thanks:: Andrew Maclean andre.nosp@m.w.am.nosp@m.aclea.nosp@m.n@gm.nosp@m.ail.c.nosp@m.om for creating and contributing the class.

Tests:: vtkParametricRandomHills (Tests)

Definition at line 47 of file vtkParametricRandomHills.h.

Member Typedef Documentation

typedef vtkParametricFunction vtkParametricRandomHills::Superclass

Definition at line 52 of file vtkParametricRandomHills.h.

Constructor & Destructor Documentation

vtkParametricRandomHills::vtkParametricRandomHills ( )

protected

vtkParametricRandomHills::~vtkParametricRandomHills ( )

overrideprotected

Member Function Documentation

static vtkTypeBool vtkParametricRandomHills::IsTypeOf ( const char * type )

static

virtual vtkTypeBool vtkParametricRandomHills::IsA ( const char * name )

virtual

Return 1 if this class is the same type of (or a subclass of) the named class.

Returns 0 otherwise. This method works in combination with vtkTypeMacro found in vtkSetGet.h.

Reimplemented from vtkParametricFunction.

static vtkParametricRandomHills* vtkParametricRandomHills::SafeDownCast ( vtkObjectBase * o )

static

virtual vtkObjectBase* vtkParametricRandomHills::NewInstanceInternal ( ) const

protectedvirtual

Reimplemented from vtkParametricFunction.

vtkParametricRandomHills* vtkParametricRandomHills::NewInstance ( ) const

void vtkParametricRandomHills::PrintSelf	(	ostream &	os,
		vtkIndent	indent
	)

overridevirtual

Methods invoked by print to print information about the object including superclasses.

Typically not called by the user (use Print() instead) but used in the hierarchical print process to combine the output of several classes.

Reimplemented from vtkParametricFunction.

int vtkParametricRandomHills::GetDimension ( )

inlineoverridevirtual

Return the parametric dimension of the class.

Implements vtkParametricFunction.

Definition at line 58 of file vtkParametricRandomHills.h.

static vtkParametricRandomHills* vtkParametricRandomHills::New ( )

static

Construct a surface of random hills with the following parameters: MinimumU = -10, MaximumU = 10, MinimumV = -10, MaximumV = 10, JoinU = 0, JoinV = 0, TwistU = 0, TwistV = 0; ClockwiseOrdering = 0, DerivativesAvailable = 0, Number of hills = 30, Variance of the hills 2.5 in both x- and y- directions, Scaling factor for the variances 1/3 in both x- and y- directions, Amplitude of each hill = 2, Scaling factor for the amplitude = 1/3, RandomSeed = 1, AllowRandomGeneration = 1.

virtual void vtkParametricRandomHills::SetNumberOfHills ( int )

virtual

Set/Get the number of hills.

Default is 30.

virtual int vtkParametricRandomHills::GetNumberOfHills ( )

virtual

Set/Get the number of hills.

Default is 30.

virtual void vtkParametricRandomHills::SetHillXVariance ( double )

virtual

Set/Get the hill variance in the x-direction.

Default is 2.5.

virtual double vtkParametricRandomHills::GetHillXVariance ( )

virtual

Set/Get the hill variance in the x-direction.

Default is 2.5.

virtual void vtkParametricRandomHills::SetHillYVariance ( double )

virtual

Set/Get the hill variance in the y-direction.

Default is 2.5.

virtual double vtkParametricRandomHills::GetHillYVariance ( )

virtual

Set/Get the hill variance in the y-direction.

Default is 2.5.

virtual void vtkParametricRandomHills::SetHillAmplitude ( double )

virtual

Set/Get the hill amplitude (height).

Default is 2.

virtual double vtkParametricRandomHills::GetHillAmplitude ( )

virtual

Set/Get the hill amplitude (height).

Default is 2.

virtual void vtkParametricRandomHills::SetRandomSeed ( int )

virtual

Set/Get the Seed for the random number generator, a value of 1 will initialize the random number generator, a negative value will initialize it with the system time.

Default is 1.

virtual int vtkParametricRandomHills::GetRandomSeed ( )

virtual

Set/Get the Seed for the random number generator, a value of 1 will initialize the random number generator, a negative value will initialize it with the system time.

Default is 1.

virtual void vtkParametricRandomHills::SetAllowRandomGeneration ( vtkTypeBool )

virtual

Set/Get the random generation flag.

A value of 0 will disable the generation of random hills on the surface allowing a reproducible number of identically shaped hills to be generated. If zero, then the number of hills used will be the nearest perfect square less than or equal to the number of hills. For example, selecting 30 hills will result in a 5 X 5 array of hills being generated. Thus a square array of hills will be generated.

Any other value means that the hills will be placed randomly on the surface. Default is 1.

virtual vtkTypeBool vtkParametricRandomHills::GetAllowRandomGeneration ( )

virtual

Set/Get the random generation flag.

A value of 0 will disable the generation of random hills on the surface allowing a reproducible number of identically shaped hills to be generated. If zero, then the number of hills used will be the nearest perfect square less than or equal to the number of hills. For example, selecting 30 hills will result in a 5 X 5 array of hills being generated. Thus a square array of hills will be generated.

Any other value means that the hills will be placed randomly on the surface. Default is 1.

virtual void vtkParametricRandomHills::AllowRandomGenerationOn ( )

virtual

Set/Get the random generation flag.

A value of 0 will disable the generation of random hills on the surface allowing a reproducible number of identically shaped hills to be generated. If zero, then the number of hills used will be the nearest perfect square less than or equal to the number of hills. For example, selecting 30 hills will result in a 5 X 5 array of hills being generated. Thus a square array of hills will be generated.

Any other value means that the hills will be placed randomly on the surface. Default is 1.

virtual void vtkParametricRandomHills::AllowRandomGenerationOff ( )

virtual

Set/Get the random generation flag.

A value of 0 will disable the generation of random hills on the surface allowing a reproducible number of identically shaped hills to be generated. If zero, then the number of hills used will be the nearest perfect square less than or equal to the number of hills. For example, selecting 30 hills will result in a 5 X 5 array of hills being generated. Thus a square array of hills will be generated.

Any other value means that the hills will be placed randomly on the surface. Default is 1.

virtual void vtkParametricRandomHills::SetXVarianceScaleFactor ( double )

virtual

Set/Get the scaling factor for the variance in the x-direction.

Default is 1/3.

virtual double vtkParametricRandomHills::GetXVarianceScaleFactor ( )

virtual

Set/Get the scaling factor for the variance in the x-direction.

Default is 1/3.

virtual void vtkParametricRandomHills::SetYVarianceScaleFactor ( double )

virtual

Set/Get the scaling factor for the variance in the y-direction.

Default is 1/3.

virtual double vtkParametricRandomHills::GetYVarianceScaleFactor ( )

virtual

Set/Get the scaling factor for the variance in the y-direction.

Default is 1/3.

virtual void vtkParametricRandomHills::SetAmplitudeScaleFactor ( double )

virtual

Set/Get the scaling factor for the amplitude.

Default is 1/3.

virtual double vtkParametricRandomHills::GetAmplitudeScaleFactor ( )

virtual

Set/Get the scaling factor for the amplitude.

Default is 1/3.

void vtkParametricRandomHills::Evaluate	(	double	uvw[3],
		double	Pt[3],
		double	Duvw[9]
	)

overridevirtual

Construct a terrain consisting of hills on a surface.

This function performs the mapping $f(u,v) \rightarrow (x,y,x)$ , returning it as Pt. It also returns the partial derivatives Du and Dv. $Pt = (x, y, z), Du = (dx/du, dy/du, dz/du), Dv = (dx/dv, dy/dv, dz/dv)$ . Then the normal is $N = Du X Dv$ .

Implements vtkParametricFunction.

double vtkParametricRandomHills::EvaluateScalar	(	double	uvw[3],
		double	Pt[3],
		double	Duvw[9]
	)

overridevirtual

Calculate a user defined scalar using one or all of uvw, Pt, Duvw.

uvw are the parameters with Pt being the Cartesian point, Duvw are the derivatives of this point with respect to u, v and w. Pt, Duvw are obtained from Evaluate().

This function is only called if the ScalarMode has the value vtkParametricFunctionSource::SCALAR_FUNCTION_DEFINED

If the user does not need to calculate a scalar, then the instantiated function should return zero.

Implements vtkParametricFunction.