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Lts/Viewer/SituationMap/MathUtils/path_rasterer.cpp

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+/**
+**
+** @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