/**
**
** @RDE_HEADER@
** Rasterize functional path geometries to polylines
** $Id$
** $HeadURL$
** $Author$
**
** -----------------------------------------------------------------------------------------------
**
** Hardware-Environment: Intel-PC
** Software-Environment: Windows 7, Qt 5.4. ArcGIS 10.2.5
**
** Language ........: C++ 11
**
** -----------------------------------------------------------------------------------------------
**
** Author ...........: Jörg Turla, SPD G, Tel. 3132
**
** -----------------------------------------------------------------------------------------------
**
** Notes .........:
**
**   12.08.2015, JT  : First edition for use with Qt5
**
** -----------------------------------------------------------------------------------------------
*/

#include "path_rasterer.h"
#include <cmath>

namespace SituationMap { namespace MathUtils
{
   PathRasterer::PathRasterer() : _eps(1.0), _maxVertexCount(0)
   {
   } /* PathRasterer::PathRasterer */
   

   void PathRasterer::rasterize(qreal tMin, qreal tMax, QVector<QPointF> & vertexList) { exeRasterize( tMin, tMax, vertexList ); }
   void PathRasterer::rasterize(qreal tMin, qreal tMax, QList<QPointF>   & vertexList) { exeRasterize( tMin, tMax, vertexList ); }


   template <class List> void PathRasterer::exeRasterize( qreal tMin, qreal tMax, List & vertexList )
   {
      vertexList.clear();

      if (tMin >= tMax) return;
      
      QPointF vMin, vMax;

      function( tMax, vMax );
      function( tMin, vMin );
      vertexList.append(vMin);
      splitSegment( vMin, tMin, vMax, tMax, _maxVertexCount, vertexList );
      vertexList.append(vMax);
   } /* PathRasterer::exeRasterize */


   template <class List> void PathRasterer::splitSegment( const QPointF & v0
                                                        , qreal           t0
                                                        , const QPointF & v1
                                                        , qreal           t1
                                                        , unsigned int    maxVertexCount
                                                        , List          & vertexList      )
   {
      if (maxVertexCount < 1)
        return;

      QPointF v2;
      qreal   t2 = (t0+t1) * 0.5;

      function( t2, v2 );

      auto length = []( const QPointF & v ) -> qreal { return sqrt(v.x()*v.x() + v.y()*v.y()); };

      qreal l0 = length(v1-v0);
      qreal l1 = length(v1-v2);
      qreal l2 = length(v2-v0);


      /* -------------------------------------------------------------------------
       * Berechnen der Höhe des Dreiecks über l0 für den Vergleich mit
       * dem Schwellwert (siehe Kosinussatz, Trigonometrische Funktionen, etc.).
       * ------------------------------------------------------------------------- */

      qreal cosPhi = (l2*l2+l0*l0-l1*l1)/(2.0*l2*l0);
      qreal h_eps  = l2*sqrt(1.0-cosPhi*cosPhi);

      // (maxVertexCount > 0) -> see pre-condition
      if  (((std::isnan(h_eps)) || (h_eps > _eps)))
      {
         maxVertexCount /= 2;
         splitSegment( v0, t0, v2, t2, maxVertexCount, vertexList );
         vertexList.append( v2 );
         splitSegment( v2, t2, v1, t1, maxVertexCount, vertexList );
      }
   } /* PathRasterer::splitSegment */

} } // namespace SituationMap::MathUtils