projections/impl/adjlon.hpp

0001 // Boost.Geometry (aka GGL, Generic Geometry Library)
0002 // This file is manually converted from PROJ4
0003
0004 // Copyright (c) 2008-2012 Barend Gehrels, Amsterdam, the Netherlands.
0005
0006 // Use, modification and distribution is subject to the Boost Software License,
0007 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
0008 // http://www.boost.org/LICENSE_1_0.txt)
0009
0010 // This file is converted from PROJ4, http://trac.osgeo.org/proj
0011 // PROJ4 is originally written by Gerald Evenden (then of the USGS)
0012 // PROJ4 is maintained by Frank Warmerdam
0013 // PROJ4 is converted to Geometry Library by Barend Gehrels (Geodan, Amsterdam)
0014
0015 // Original copyright notice:
0016
0017 // Permission is hereby granted, free of charge, to any person obtaining a
0018 // copy of this software and associated documentation files (the "Software"),
0019 // to deal in the Software without restriction, including without limitation
0020 // the rights to use, copy, modify, merge, publish, distribute, sublicense,
0021 // and/or sell copies of the Software, and to permit persons to whom the
0022 // Software is furnished to do so, subject to the following conditions:
0023
0024 // The above copyright notice and this permission notice shall be included
0025 // in all copies or substantial portions of the Software.
0026
0027 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
0028 // OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
0029 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
0030 // THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
0031 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
0032 // FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
0033 // DEALINGS IN THE SOFTWARE.
0034
0035 #ifndef BOOST_GEOMETRY_PROJECTIONS_IMPL_ADJLON_HPP
0036 #define BOOST_GEOMETRY_PROJECTIONS_IMPL_ADJLON_HPP
0037
0038 #include <boost/math/constants/constants.hpp>
0039 #include <boost/geometry/util/math.hpp>
0040
0041 namespace boost { namespace geometry { namespace projections
0042 {
0043
0044 namespace detail
0045 {
0046
0047 /* reduce argument to range +/- PI */
0048 template <typename T>
0049 inline T adjlon (T lon)
0050 {
0051     if (geometry::math::abs(lon) <= boost::math::constants::pi<T>())
0052     {
0053         return lon;
0054     }
0055
0056     /* adjust to 0..2pi rad */
0057     lon += boost::math::constants::pi<T>();
0058     /* remove integral # of 'revolutions'*/
0059     lon -= boost::math::constants::two_pi<T>() *
0060                 std::floor(lon / boost::math::constants::two_pi<T>());
0061     /* adjust back to -pi..pi rad */
0062     lon -= boost::math::constants::pi<T>();
0063
0064     return lon;
0065 }
0066
0067 } // namespace detail
0068 }}} // namespace boost::geometry::projections
0069
0070 #endif // BOOST_GEOMETRY_PROJECTIONS_IMPL_ADJLON_HPP