.TH "QwtSplineParametrization" 3 "Sun Jul 18 2021" "Version 6.2.0" "Qwt User's Guide" \" -*- nroff -*-
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.SH NAME
QwtSplineParametrization \- Curve parametrization used for a spline interpolation\&.  

.SH SYNOPSIS
.br
.PP
.PP
\fC#include <qwt_spline_parametrization\&.h>\fP
.SS "Public Types"

.in +1c
.ti -1c
.RI "enum \fBType\fP { \fBParameterX\fP, \fBParameterY\fP, \fBParameterUniform\fP, \fBParameterChordal\fP, \fBParameterCentripetal\fP, \fBParameterManhattan\fP }"
.br
.RI "Parametrization type\&. "
.in -1c
.SS "Public Member Functions"

.in +1c
.ti -1c
.RI "\fBQwtSplineParametrization\fP (int \fBtype\fP)"
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.ti -1c
.RI "virtual \fB~QwtSplineParametrization\fP ()"
.br
.RI "Destructor\&. "
.ti -1c
.RI "int \fBtype\fP () const"
.br
.ti -1c
.RI "virtual double \fBvalueIncrement\fP (const QPointF &, const QPointF &) const"
.br
.RI "Calculate the parameter value increment for 2 points\&. "
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.SS "Static Public Member Functions"

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.ti -1c
.RI "static double \fBvalueIncrementX\fP (const QPointF &, const QPointF &)"
.br
.RI "Calculate the ParameterX value increment for 2 points\&. "
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.RI "static double \fBvalueIncrementY\fP (const QPointF &, const QPointF &)"
.br
.RI "Calculate the ParameterY value increment for 2 points\&. "
.ti -1c
.RI "static double \fBvalueIncrementUniform\fP (const QPointF &, const QPointF &)"
.br
.RI "Calculate the ParameterUniform value increment\&. "
.ti -1c
.RI "static double \fBvalueIncrementChordal\fP (const QPointF &, const QPointF &)"
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.RI "Calculate the ParameterChordal value increment for 2 points\&. "
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.RI "static double \fBvalueIncrementCentripetal\fP (const QPointF &, const QPointF &)"
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.RI "Calculate the ParameterCentripetal value increment for 2 points\&. "
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.RI "static double \fBvalueIncrementManhattan\fP (const QPointF &, const QPointF &)"
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.RI "Calculate the ParameterManhattan value increment for 2 points\&. "
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.SH "Detailed Description"
.PP 
Curve parametrization used for a spline interpolation\&. 

Parametrization is the process of finding a parameter value for each curve point - usually related to some physical quantity ( distance, time \&.\&.\&. )\&.
.PP
Often accumulating the curve length is the intended way of parametrization, but as the interpolated curve is not known in advance an approximation needs to be used\&.
.PP
The values are calculated by cumulating increments, that are provided by \fBQwtSplineParametrization\fP\&. As the curve parameters need to be montonically increasing, each increment need to be positive\&.
.PP
.IP "\(bu" 2
t[0] = 0;
.IP "\(bu" 2
t[i] = t[i-1] + valueIncrement( point[i-1], p[i] );
.PP
.PP
\fBQwtSplineParametrization\fP provides the most common used type of parametrizations and offers an interface to inject custom implementations\&.
.PP
\fBNote\fP
.RS 4
The most relevant types of parametrization are trying to provide an approximation of the curve length\&.
.RE
.PP
\fBSee also\fP
.RS 4
\fBQwtSpline::setParametrization()\fP 
.RE
.PP

.PP
Definition at line 44 of file qwt_spline_parametrization\&.h\&.
.SH "Member Enumeration Documentation"
.PP 
.SS "enum \fBQwtSplineParametrization::Type\fP"

.PP
Parametrization type\&. 
.PP
\fBEnumerator\fP
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.TP
\fB\fIParameterX \fP\fP
No parametrization: t[i] = x[i] 
.PP
\fBSee also\fP
.RS 4
\fBvalueIncrementX()\fP 
.RE
.PP

.TP
\fB\fIParameterY \fP\fP
No parametrization: t[i] = y[i] 
.PP
\fBSee also\fP
.RS 4
\fBvalueIncrementY()\fP 
.RE
.PP

.TP
\fB\fIParameterUniform \fP\fP
Uniform parametrization: t[i] = i;
.PP
A very fast parametrization, with good results, when the geometry of the control points is somehow 'equidistant'\&. F\&.e\&. when recording the position of a body, that is moving with constant speed every n seconds\&.
.PP
\fBSee also\fP
.RS 4
\fBvalueIncrementUniform()\fP 
.RE
.PP

.TP
\fB\fIParameterChordal \fP\fP
Parametrization using the chordal length between two control points
.PP
The chordal length is the most commonly used approximation for the curve length\&.
.PP
\fBSee also\fP
.RS 4
\fBvalueIncrementChordal()\fP 
.RE
.PP

.TP
\fB\fIParameterCentripetal \fP\fP
Centripetal parametrization
.PP
Based on the square root of the chordal length\&.
.PP
Its name stems from the physical observations regarding the centripetal force, of a body moving along the curve\&.
.PP
\fBSee also\fP
.RS 4
\fBvalueIncrementCentripetal()\fP 
.RE
.PP

.TP
\fB\fIParameterManhattan \fP\fP
Parametrization using the manhattan length between two control points
.PP
Approximating the curve length by the manhattan length is faster than the chordal length, but usually gives worse results\&.
.PP
\fBSee also\fP
.RS 4
\fBvalueIncrementManhattan()\fP 
.RE
.PP

.PP
Definition at line 48 of file qwt_spline_parametrization\&.h\&.
.SH "Constructor & Destructor Documentation"
.PP 
.SS "QwtSplineParametrization::QwtSplineParametrization (int type)\fC [explicit]\fP"
Constructor 
.PP
\fBParameters\fP
.RS 4
\fItype\fP Parametrization type 
.RE
.PP
\fBSee also\fP
.RS 4
\fBtype()\fP 
.RE
.PP

.PP
Definition at line 17 of file qwt_spline_parametrization\&.cpp\&.
.SH "Member Function Documentation"
.PP 
.SS "int QwtSplineParametrization::type () const"

.PP
\fBReturns\fP
.RS 4
Parametrization type 
.RE
.PP

.PP
Definition at line 72 of file qwt_spline_parametrization\&.cpp\&.
.SS "double QwtSplineParametrization::valueIncrement (const QPointF & point1, const QPointF & point2) const\fC [virtual]\fP"

.PP
Calculate the parameter value increment for 2 points\&. 
.PP
\fBParameters\fP
.RS 4
\fIpoint1\fP First point 
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\fIpoint2\fP Second point
.RE
.PP
\fBReturns\fP
.RS 4
Value increment 
.RE
.PP

.PP
Definition at line 35 of file qwt_spline_parametrization\&.cpp\&.
.SS "double QwtSplineParametrization::valueIncrementCentripetal (const QPointF & point1, const QPointF & point2)\fC [inline]\fP, \fC [static]\fP"

.PP
Calculate the ParameterCentripetal value increment for 2 points\&. 
.PP
\fBParameters\fP
.RS 4
\fIpoint1\fP First point 
.br
\fIpoint2\fP Second point
.RE
.PP
\fBReturns\fP
.RS 4
The square root of a chordal increment 
.RE
.PP

.PP
Definition at line 196 of file qwt_spline_parametrization\&.h\&.
.SS "double QwtSplineParametrization::valueIncrementChordal (const QPointF & point1, const QPointF & point2)\fC [inline]\fP, \fC [static]\fP"

.PP
Calculate the ParameterChordal value increment for 2 points\&. 
.PP
\fBParameters\fP
.RS 4
\fIpoint1\fP First point 
.br
\fIpoint2\fP Second point
.RE
.PP
\fBReturns\fP
.RS 4
qSqrt( dx * dx + dy * dy ); 
.RE
.PP

.PP
Definition at line 179 of file qwt_spline_parametrization\&.h\&.
.SS "double QwtSplineParametrization::valueIncrementManhattan (const QPointF & point1, const QPointF & point2)\fC [inline]\fP, \fC [static]\fP"

.PP
Calculate the ParameterManhattan value increment for 2 points\&. 
.PP
\fBParameters\fP
.RS 4
\fIpoint1\fP First point 
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\fIpoint2\fP Second point
.RE
.PP
\fBReturns\fP
.RS 4
| point2\&.x() - point1\&.x() | + | point2\&.y() - point1\&.y() | 
.RE
.PP

.PP
Definition at line 210 of file qwt_spline_parametrization\&.h\&.
.SS "double QwtSplineParametrization::valueIncrementUniform (const QPointF & point1, const QPointF & point2)\fC [inline]\fP, \fC [static]\fP"

.PP
Calculate the ParameterUniform value increment\&. 
.PP
\fBParameters\fP
.RS 4
\fIpoint1\fP First point 
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\fIpoint2\fP Second point
.RE
.PP
\fBReturns\fP
.RS 4
1\&.0 
.RE
.PP

.PP
Definition at line 162 of file qwt_spline_parametrization\&.h\&.
.SS "double QwtSplineParametrization::valueIncrementX (const QPointF & point1, const QPointF & point2)\fC [inline]\fP, \fC [static]\fP"

.PP
Calculate the ParameterX value increment for 2 points\&. 
.PP
\fBParameters\fP
.RS 4
\fIpoint1\fP First point 
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\fIpoint2\fP Second point
.RE
.PP
\fBReturns\fP
.RS 4
point2\&.x() - point1\&.x(); 
.RE
.PP

.PP
Definition at line 134 of file qwt_spline_parametrization\&.h\&.
.SS "double QwtSplineParametrization::valueIncrementY (const QPointF & point1, const QPointF & point2)\fC [inline]\fP, \fC [static]\fP"

.PP
Calculate the ParameterY value increment for 2 points\&. 
.PP
\fBParameters\fP
.RS 4
\fIpoint1\fP First point 
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\fIpoint2\fP Second point
.RE
.PP
\fBReturns\fP
.RS 4
point2\&.y() - point1\&.y(); 
.RE
.PP

.PP
Definition at line 148 of file qwt_spline_parametrization\&.h\&.

.SH "Author"
.PP 
Generated automatically by Doxygen for Qwt User's Guide from the source code\&.