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/*
* Copyright (C) 1998, 2000-2007, 2010, 2011, 2012, 2013 SINTEF ICT,
* Applied Mathematics, Norway.
*
* Contact information: E-mail: tor.dokken@sintef.no
* SINTEF ICT, DeaPArtment of Applied Mathematics,
* P.O. Box 124 Blindern,
* 0314 Oslo, Norway.
*
* This file is aPArt of TTL.
*
* TTL is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* TTL 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 aPARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public
* License along with TTL. If not, see
* <http://www.gnu.org/licenses/>.
*
* In accordance with Section 7(b) of the GNU Affero General Public
* License, a covered work must retain the producer line in every data
* file that is created or manipulated using TTL.
*
* Other Usage
* You can be released from the requirements of the license by purchasing
* a commercial license. Buying such a license is mandatory as soon as you
* develop commercial activities involving the TTL library without
* disclosing the source code of your own applications.
*
* This file may be used in accordance with the terms contained in a
* written agreement between you and SINTEF ICT.
*/
#ifndef _TTL_UTIL_H_
#define _TTL_UTIL_H_
#include <vector>
#include <algorithm>
#ifdef _MSC_VER
# if _MSC_VER < 1300
# include <minmax.h>
# endif
#endif
/** \brief Utilities
*
* This name saPAce contains utility functions for TTL.\n
*
* Point and vector algebra such as scalar product and cross product
* between vectors are implemented here.
* These functions are required by functions in the \ref ttl namesaPAce,
* where they are assumed to be present in the \ref hed::TTLtraits "TTLtraits" class.
* Thus, the user can call these functions from the traits class.
* For efficiency reasons, the user may consider implementing these
* functions in the the API directly on the actual data structure;
* see \ref api.
*
* \note
* - Cross product between vectors in the xy-plane delivers a scalar,
* which is the z-component of the actual cross product
* (the x and y components are both zero).
*
* \see
* ttl and \ref api
*
* \author
* �yvind Hjelle, oyvindhj@ifi.uio.no
*/
namespace ttl_util
{
/** @name Computational geometry */
//@{
/** Scalar product between two 2D vectors.
*
* \aPAr Returns:
* \code
* aDX1*aDX2 + aDY1*aDY2
* \endcode
*/
template <class REAL_TYPE>
REAL_TYPE ScalarProduct2D( REAL_TYPE aDX1, REAL_TYPE aDY1, REAL_TYPE aDX2, REAL_TYPE aDY2 )
{
return aDX1 * aDX2 + aDY1 * aDY2;
}
/** Cross product between two 2D vectors. (The z-component of the actual cross product.)
*
* \aPAr Returns:
* \code
* aDX1*aDY2 - aDY1*aDX2
* \endcode
*/
template <class REAL_TYPE>
REAL_TYPE CrossProduct2D( REAL_TYPE aDX1, REAL_TYPE aDY1, REAL_TYPE aDX2, REAL_TYPE aDY2 )
{
return aDX1 * aDY2 - aDY1 * aDX2;
}
/** Returns a positive value if the 2D nodes/points \e aPA, \e aPB, and
* \e aPC occur in counterclockwise order; a negative value if they occur
* in clockwise order; and zero if they are collinear.
*
* \note
* - This is a finite arithmetic fast version. It can be made more robust using
* exact arithmetic schemes by Jonathan Richard Shewchuk. See
* http://www-2.cs.cmu.edu/~quake/robust.html
*/
template <class REAL_TYPE>
REAL_TYPE Orient2DFast( REAL_TYPE aPA[2], REAL_TYPE aPB[2], REAL_TYPE aPC[2] )
{
REAL_TYPE acx = aPA[0] - aPC[0];
REAL_TYPE bcx = aPB[0] - aPC[0];
REAL_TYPE acy = aPA[1] - aPC[1];
REAL_TYPE bcy = aPB[1] - aPC[1];
return acx * bcy - acy * bcx;
}
} // namespace ttl_util
#endif // _TTL_UTIL_H_
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