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/*
**************************************************************************
description
--------------------
copyright : (C) 2002 by Andreas Zehender
email : zehender@kde.org
**************************************************************************
**************************************************************************
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 2 of the License, or *
* (at your option) any later version. *
* *
**************************************************************************/
#include "pmsplinesegment.h"
PMVector PMSplineSegment::point( double t ) const
{
double t2 = t * t;
double t3 = t2 * t;
return PMVector( m_a[0]*t3 + m_b[0]*t2 + m_c[0]*t + m_d[0],
m_a[1]*t3 + m_b[1]*t2 + m_c[1]*t + m_d[1] );
}
PMVector PMSplineSegment::gradient( double t ) const
{
double t2 = t * t;
return PMVector( 3*m_a[0]*t2 + 2*m_b[0]*t + m_c[0],
3*m_a[1]*t2 + 2*m_b[1]*t + m_c[1] );
}
void PMSplineSegment::calculateLinear( const PMVector& p1, const PMVector& p2 )
{
m_a[0] = 0.0;
m_b[0] = 0.0;
m_c[0] = -1.0 * p1[0] + 1.0 * p2[0];
m_d[0] = 1.0 * p1[0];
m_a[1] = 0.0;
m_b[1] = 0.0;
m_c[1] = -1.0 * p1[1] + 1.0 * p2[1];
m_d[1] = 1.0 * p1[1];
}
void PMSplineSegment::calculateQuadratic( const PMVector& p1,
const PMVector& p2,
const PMVector& p3 )
{
m_a[0] = 0.0;
m_b[0] = 0.5 * p1[0] - 1.0 * p2[0] + 0.5 * p3[0];
m_c[0] = -0.5 * p1[0] + 0.5 * p3[0];
m_d[0] = 1.0 * p2[0];
m_a[1] = 0.0;
m_b[1] = 0.5 * p1[1] - 1.0 * p2[1] + 0.5 * p3[1];
m_c[1] = -0.5 * p1[1] + 0.5 * p3[1];
m_d[1] = 1.0 * p2[1];
}
void PMSplineSegment::calculateCubic( const PMVector& p1, const PMVector& p2,
const PMVector& p3, const PMVector& p4 )
{
m_a[0] = -0.5 * p1[0] + 1.5 * p2[0] - 1.5 * p3[0] + 0.5 * p4[0];
m_b[0] = p1[0] - 2.5 * p2[0] + 2.0 * p3[0] - 0.5 * p4[0];
m_c[0] = -0.5 * p1[0] + 0.5 * p3[0];
m_d[0] = p2[0];
m_a[1] = -0.5 * p1[1] + 1.5 * p2[1] - 1.5 * p3[1] + 0.5 * p4[1];
m_b[1] = p1[1] - 2.5 * p2[1] + 2.0 * p3[1] - 0.5 * p4[1];
m_c[1] = -0.5 * p1[1] + 0.5 * p3[1];
m_d[1] = p2[1];
}
void PMSplineSegment::calculateBezier( const PMVector& p1, const PMVector& p2,
const PMVector& p3, const PMVector& p4 )
{
m_a[0] = - p1[0] + 3.0 * p2[0] - 3.0 * p3[0] + p4[0];
m_b[0] = 3.0 * p1[0] - 6.0 * p2[0] + 3.0 * p3[0];
m_c[0] = -3.0 * p1[0] + 3.0 * p2[0];
m_d[0] = p1[0];
m_a[1] = - p1[1] + 3.0 * p2[1] - 3.0 * p3[1] + p4[1];
m_b[1] = 3.0 * p1[1] - 6.0 * p2[1] + 3.0 * p3[1];
m_c[1] = -3.0 * p1[1] + 3.0 * p2[1];
m_d[1] = p1[1];
}
void PMSplineSegment::calculateQuadricBezier( const PMVector& p1,
const PMVector& p2,
const PMVector& p3 )
{
m_a[0] = 0;
m_b[0] = p1[0] - 2.0 * p2[0] + p3[0];
m_c[0] = -2.0 * p1[0] + 2.0 * p2[0];
m_d[0] = p1[0];
m_a[1] = 0;
m_b[1] = p1[1] - 2.0 * p2[1] + p3[1];
m_c[1] = -2.0 * p1[1] + 2.0 * p2[1];
m_d[1] = p1[1];
}
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