Go::CrossTangentOffset Class Reference
['geometry' - a spline library]

This curve represent an offset curve from a given space curve, along a direction obtained by blending two 'cross-tangent curves', and with an offset distance which is a linear function interpolating the cross-tangent length at the start and end of the curve. More...

#include <CrossTangentOffset.h>

Inheritance diagram for Go::CrossTangentOffset:

List of all members.

Public Member Functions
	CrossTangentOffset (boost::shared_ptr< SplineCurve > &poscurve, boost::shared_ptr< SplineCurve > &tangcv1, boost::shared_ptr< SplineCurve > &tangcv2, boost::shared_ptr< SplineCurve > &blend1, boost::shared_ptr< SplineCurve > &blend2)
	Constructor, taking a curve from which we take the offset, and four other curves used to calculate the offset direction and magnitude.
virtual	~CrossTangentOffset ()
	virtual destructor enables safe inheritance
virtual Point	eval (double t) const
	Evaluate a point on the curve for a given parameter.
virtual void	eval (double t, int n, Point der[]) const
	Evaluate a point and a certain number of derivatives on the curve for a given parameter.
virtual double	start () const
	Get the start parameter of the curve.
virtual double	end () const
	Get the end parameter of the curve.
virtual int	dim () const
	Get the dimension of the space in which the curve lies.
virtual bool	approximationOK (double par, Point approxpos, double tol1, double tol2) const
	Inherited from EvalCurve::approximationOK().

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Detailed Description

This curve represent an offset curve from a given space curve, along a direction obtained by blending two 'cross-tangent curves', and with an offset distance which is a linear function interpolating the cross-tangent length at the start and end of the curve.

Definition at line 53 of file CrossTangentOffset.h.

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Constructor & Destructor Documentation

Go::CrossTangentOffset::CrossTangentOffset	(	boost::shared_ptr< SplineCurve > &	poscurve,
		boost::shared_ptr< SplineCurve > &	tangcv1,
		boost::shared_ptr< SplineCurve > &	tangcv2,
		boost::shared_ptr< SplineCurve > &	blend1,
		boost::shared_ptr< SplineCurve > &	blend2
	)

Constructor, taking a curve from which we take the offset, and four other curves used to calculate the offset direction and magnitude.

Two of these curves are the cross-tangent curves and the two other are blending functions (dimension 1). To find the offset direction at a given point, the two cross-tangent curves are evaluated at the specified parameter, multiplied by their respective blending functions and added together. The offset length is computed by linearly interpolating the length of this blended cross-tangent at the start and end parameter of the curve.

Parameters:

	poscurve	the curve from which we take the offset
	tangcv1	the first cross-tangent curve
	tangcv2	the second cross-tangent curve
	blend1	the blending function for the first cross-tangent curve
	blend2	the blending function for the second cross-tangent curve

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Member Function Documentation

virtual Point Go::CrossTangentOffset::eval

(

double

t

)

const [virtual]

Evaluate a point on the curve for a given parameter.

Parameters:

t

the parameter for which to evaluate the curve.

Returns:

the evaluated point

Implements Go::EvalCurve.

virtual void Go::CrossTangentOffset::eval	(	double	t,
		int	n,
		Point	der[]
	)			const [virtual]

Evaluate a point and a certain number of derivatives on the curve for a given parameter.

Parameters:

	t	the parameter for which to evaluate the curve.
	n	the number of derivatives (0 or more)

Return values:

der

pointer to an array of Points where the result will be written. The position will be stored first, then the first derivative (tangent), then the second, etc.. NB: For most (all) derived classes of 'EvalCurve', the implementation actually only supports the computation of one derivative, i.e. if n > 1, only one derivative will be computed anyway.

Implements Go::EvalCurve.

virtual double Go::CrossTangentOffset::start

(

)

const [virtual]

Get the start parameter of the curve.

Returns:

the start parameter of the curve.

Implements Go::EvalCurve.

virtual double Go::CrossTangentOffset::end

(

)

const [virtual]

Get the end parameter of the curve.

Returns:

the end parameter of the curve.

Implements Go::EvalCurve.

virtual int Go::CrossTangentOffset::dim

(

)

const [virtual]

Get the dimension of the space in which the curve lies.

Returns:

the space dimension of the curve.

Implements Go::EvalCurve.

virtual bool Go::CrossTangentOffset::approximationOK	(	double	par,
		Point	approxpos,
		double	tol1,
		double	tol2
	)			const [virtual]

Inherited from EvalCurve::approximationOK().

For this class, both tolerances are used.

Parameters:

	par	the parameter at which to check the curve
	approxpos	the position we want to check whether or not the curve approximates for parameter 'par'.
	tol1	spatial approximation tolerance. If the evaluated position is outside this tolerance, 'false' is returned. If it inside this tolerance "by far", 'true' is returned. Otherwise, 'tol2' is taken into account.
	tol2	This tolerance is taken into account when the evaluated point is within 'tol1' from 'approxpos', but not convincingly so. In that case this tolerance is used to check whether the evaluated cross tangent lies in the plane spanned by the tangent curves at this point. (It is thus an angle tolerance).

Returns:

'true' if the curve approximates the point at the parameter, 'false' otherwise.

Implements Go::EvalCurve.

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

• CrossTangentOffset.h

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