CSinCosLookUpTableFor2DScans.cpp

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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          |
   +------------------------------------------------------------------------+ */

#include "obs-precomp.h"  // Precompiled headers

#include <mrpt/obs/CObservation2DRangeScan.h>
#include <mrpt/obs/CSinCosLookUpTableFor2DScans.h>

using namespace std;
using namespace mrpt::obs;

/** 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.
 */
const CSinCosLookUpTableFor2DScans::TSinCosValues&
    CSinCosLookUpTableFor2DScans::getSinCosForScan(
        const CObservation2DRangeScan& scan) const
{
    T2DScanProperties scan_prop;
    scan.getScanProperties(scan_prop);
    return getSinCosForScan(scan_prop);
}

/** 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.
 */
const CSinCosLookUpTableFor2DScans::TSinCosValues&
    CSinCosLookUpTableFor2DScans::getSinCosForScan(
        const T2DScanProperties& scan_prop) const
{
    std::lock_guard lck(m_cache_mtx);

    auto it = m_cache.find(scan_prop);
    if (it != m_cache.end())
    {  // Found in the cache:
        return it->second;
    }
    else
    {
        // If there're too many LUTs, something is wrong, so just free the
        // memory:
        // (If you someday find someone with TWENTY *different* laser scanner
        // models,
        //   please, accept my apologies... but send me a photo of them all!!
        //   ;-)
        if (m_cache.size() > 20) m_cache.clear();

        // Compute and insert in the cache:
        TSinCosValues& new_entry = m_cache[scan_prop];

        // Make sure the allocated memory at least have room for 4 extra
        // double's at the end,
        //  for the case we use these buffers for SSE2 optimized code. If the
        //  final values are uninitialized it doesn't matter.
        new_entry.ccos.resize(scan_prop.nRays + 4);
        new_entry.csin.resize(scan_prop.nRays + 4);

        ASSERT_(scan_prop.nRays >= 2);
        if (scan_prop.nRays > 0)
        {
            double Ang =
                (scan_prop.rightToLeft ? -0.5 : +0.5) * scan_prop.aperture;
            const double dA = (scan_prop.rightToLeft ? 1.0 : -1.0) *
                              (scan_prop.aperture / (scan_prop.nRays - 1));

            for (size_t i = 0; i < scan_prop.nRays; i++)
            {
                new_entry.ccos[i] = d2f(cos(Ang));
                new_entry.csin[i] = d2f(sin(Ang));
                Ang += dA;
            }
        }
        // return them:
        return new_entry;
    }
}