/* This file is part of the KDE project
   Copyright (C) 2001-2002 Lennart Kudling <kudling@kde.org>
   Copyright (C) 2002-2003 Rob Buis <buis@kde.org>
   Copyright (C) 2005 Thomas Zander <zander@kde.org>
   Copyright (C) 2006 Tim Beaulen <tbscope@gmail.com>
   Copyright (C) 2008 Jan Hambrecht <jaham@gmx.net>

   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public
   License as published by the Free Software Foundation; either
   version 2 of the License, or (at your option) any later version.

   This library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public License
   along with this library; see the file COPYING.LIB.  If not, write to
   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
*/

#ifndef KARBONGLOBAL_H
#define KARBONGLOBAL_H

#include <karboncommon_export.h>

#include <kglobal.h>
#include <QPointF>
#include <QMatrix>

// define some often used mathematical constants et al:

// TODO: optimize those values.

namespace KarbonGlobal
{
    const qreal pi			=  3.14159265358979323846;	// pi
    const qreal twopi		=  6.28318530717958647692;	// 2pi
    const qreal pi_2		=  1.57079632679489661923;	// pi/2
    const qreal pi_180		=  0.01745329251994329576;	// pi/180
    const qreal one_pi_180	= 57.29577951308232087684;	// 180/pi
    const qreal sqrt2		=  1.41421356237309504880;	// sqrt(2)
    const qreal one_3		=  0.33333333333333333333;	// 1/3
    const qreal two_3		=  0.66666666666666666667;	// 2/3
    const qreal one_6		=  0.16666666666666666667;	// 1/6
    const qreal one_7		=  0.14285714285714285714;	// 1/7

    /**
    * Constants used to decide if a number is equal zero or nearly the same
    * as another number.
    */
    const qreal veryBigNumber = 1.0e8;
    const qreal verySmallNumber = 1.0e-8;

    /**
    * A bezier with this flatness is considered "flat". Used in subdividing.
    */
    const qreal flatnessTolerance = 0.01;

    /**
    * A tolerance used to approximate bezier lengths. If the relative difference
    * between chordlength and polylength (length of the controlpolygon) is smaller
    * than this value, the length of the bezier is 1/2 chordlength + 1/2 polylength.
    */
    const qreal lengthTolerance = 0.005;

    /**
    * A tolerance used to calculate param t on a segment at a given arc
    * length (counting from t=0).
    * If the relative difference between a length approximation and the given
    * length is smaller than this value, they are assumed to be identical.
    */
    const qreal paramLengthTolerance = 0.001;

    /**
    * A range for the isNear() check, to decide if a QPointF "is the same"
    * as another.
    */
    const qreal isNearRange = 0.001;

    /**
    * A tolerance for multiplying normalized (length=1) vectors. A result of
    * >= parallelTolerance indicates parallel vectors.
    */
    const qreal parallelTolerance = 0.99;

    /**
    * Returns the sign of paramater a.
    */
    inline int sign( qreal a )
    {
        return a < 0.0
            ? -1
            : 1;
    }

    /**
    * Calculates the binomial coefficient n! / ( k! * ( n - k)! ).
    */
    int binomialCoeff( unsigned n, unsigned k );

    /**
    * Calculates the value ln( n! ).
    */
    qreal factorialLn( unsigned n );

    /**
    * Calculates the value ln| Gamma(x) | for x > 0.
    */
    qreal gammaLn( qreal x );

    /// Returns scalar product of two given vectors
    KARBONCOMMON_EXPORT qreal scalarProduct(const QPointF &p1, const QPointF &p2);

    bool pointsAreNear(const QPointF &p1, const QPointF &p2, qreal range);

    /// Returns the cross product of two given vectors 
    QPointF crossProduct( const QPointF &v1, const QPointF &v2 );
}

#endif // KARBONGLOBAL_H

