CSinCosLookUpTableFor2DScans.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <mrpt/math/CVectorDynamic.h>  //CVectorFloat
#include <mrpt/obs/T2DScanProperties.h>
#include <map>
#include <mutex>

namespace mrpt::obs
{
// Frwd decl:
class CObservation2DRangeScan;

/** A smart look-up-table (LUT) of sin/cos values for 2D laser scans.
 *  Refer to the main method CSinCosLookUpTableFor2DScans::getSinCosForScan()
 *
 *  This class is used in mrpt::maps::CPointsMap
 * \ingroup mrpt_obs_grp
 */
class CSinCosLookUpTableFor2DScans
{
   public:
    CSinCosLookUpTableFor2DScans() = default;
    /** Do NOT copy neither the cache nor the mutex */
    CSinCosLookUpTableFor2DScans(const CSinCosLookUpTableFor2DScans&) {}
    CSinCosLookUpTableFor2DScans& operator=(const CSinCosLookUpTableFor2DScans&)
    {
        return *this;
    }

    /** A pair of vectors with the cos and sin values. */
    struct TSinCosValues
    {
        mrpt::math::CVectorFloat ccos, csin;
    };

    /** Return two vectors with the cos and the sin of the angles for each of
     * the
     * rays in a scan, computing them only the first time and returning a
     * cached copy the rest.
     *  Usage:
     * \code
     *   CSinCosLookUpTableFor2DScans cache;
     *   ...
     *   const CSinCosLookUpTableFor2DScans::TSinCosValues & sincos_vals =
     * cache.getSinCosForScan( scan );
     * \endcode
     */
    const TSinCosValues& getSinCosForScan(
        const CObservation2DRangeScan& scan) const;
    /** \overload */
    const TSinCosValues& getSinCosForScan(
        const T2DScanProperties& scan_prop) const;

   private:
    /** The cache of known scans and their sin/cos tables. */
    mutable std::map<T2DScanProperties, TSinCosValues> m_cache;
    mutable std::recursive_mutex m_cache_mtx;
};

}  // namespace mrpt::obs