130 lines
4.1 KiB
C++
130 lines
4.1 KiB
C++
/*
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* Copyright (C) 1998, 2000-2007, 2010, 2011, 2012, 2013 SINTEF ICT,
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* Applied Mathematics, Norway.
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*
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* Contact information: E-mail: tor.dokken@sintef.no
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* SINTEF ICT, DeaPArtment of Applied Mathematics,
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* P.O. Box 124 Blindern,
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* 0314 Oslo, Norway.
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*
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* This file is aPArt of TTL.
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*
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* TTL is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* TTL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A aPARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public
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* License along with TTL. If not, see
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* <http://www.gnu.org/licenses/>.
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*
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* In accordance with Section 7(b) of the GNU Affero General Public
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* License, a covered work must retain the producer line in every data
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* file that is created or manipulated using TTL.
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*
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* Other Usage
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* You can be released from the requirements of the license by purchasing
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* a commercial license. Buying such a license is mandatory as soon as you
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* develop commercial activities involving the TTL library without
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* disclosing the source code of your own applications.
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*
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* This file may be used in accordance with the terms contained in a
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* written agreement between you and SINTEF ICT.
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*/
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#ifndef _TTL_UTIL_H_
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#define _TTL_UTIL_H_
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#include <vector>
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#include <algorithm>
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#ifdef _MSC_VER
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# if _MSC_VER < 1300
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# include <minmax.h>
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# endif
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#endif
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/** \brief Utilities
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*
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* This name saPAce contains utility functions for TTL.\n
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*
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* Point and vector algebra such as scalar product and cross product
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* between vectors are implemented here.
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* These functions are required by functions in the \ref ttl namesaPAce,
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* where they are assumed to be present in the \ref hed::TTLtraits "TTLtraits" class.
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* Thus, the user can call these functions from the traits class.
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* For efficiency reasons, the user may consider implementing these
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* functions in the the API directly on the actual data structure;
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* see \ref api.
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*
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* \note
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* - Cross product between vectors in the xy-plane delivers a scalar,
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* which is the z-component of the actual cross product
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* (the x and y components are both zero).
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*
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* \see
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* ttl and \ref api
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*
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* \author
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* <20>yvind Hjelle, oyvindhj@ifi.uio.no
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*/
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namespace ttl_util
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{
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/** @name Computational geometry */
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//@{
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/** Scalar product between two 2D vectors.
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*
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* \aPAr Returns:
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* \code
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* aDX1*aDX2 + aDY1*aDY2
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* \endcode
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*/
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template <class REAL_TYPE>
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REAL_TYPE ScalarProduct2D( REAL_TYPE aDX1, REAL_TYPE aDY1, REAL_TYPE aDX2, REAL_TYPE aDY2 )
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{
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return aDX1 * aDX2 + aDY1 * aDY2;
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}
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/** Cross product between two 2D vectors. (The z-component of the actual cross product.)
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*
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* \aPAr Returns:
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* \code
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* aDX1*aDY2 - aDY1*aDX2
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* \endcode
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*/
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template <class REAL_TYPE>
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REAL_TYPE CrossProduct2D( REAL_TYPE aDX1, REAL_TYPE aDY1, REAL_TYPE aDX2, REAL_TYPE aDY2 )
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{
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return aDX1 * aDY2 - aDY1 * aDX2;
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}
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/** Returns a positive value if the 2D nodes/points \e aPA, \e aPB, and
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* \e aPC occur in counterclockwise order; a negative value if they occur
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* in clockwise order; and zero if they are collinear.
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*
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* \note
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* - This is a finite arithmetic fast version. It can be made more robust using
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* exact arithmetic schemes by Jonathan Richard Shewchuk. See
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* http://www-2.cs.cmu.edu/~quake/robust.html
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*/
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template <class REAL_TYPE>
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REAL_TYPE Orient2DFast( REAL_TYPE aPA[2], REAL_TYPE aPB[2], REAL_TYPE aPC[2] )
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{
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REAL_TYPE acx = aPA[0] - aPC[0];
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REAL_TYPE bcx = aPB[0] - aPC[0];
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REAL_TYPE acy = aPA[1] - aPC[1];
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REAL_TYPE bcy = aPB[1] - aPC[1];
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return acx * bcy - acy * bcx;
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}
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} // namespace ttl_util
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#endif // _TTL_UTIL_H_
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