Apply a workaround in 3D_draw.cpp to avoid crash in boost::polygon (try to fix Bug #1322804)

This workaround was already used (bzr 4301, in file plot_board_layers.cpp) also to avoid similar crashes (uses 18 segments instead of 16 to approximate a circle by segments).
Minor code cleanup in dialog_plot.

3d-viewer/3d_draw.cpp

@@ -240,7 +240,12 @@ void EDA_3D_CANVAS::BuildBoard3DView()
     bool realistic_mode = g_Parm_3D_Visu.IsRealisticMode();
 
     // Number of segments to convert a circle to polygon
-    const int       segcountforcircle   = 16;
+    // Boost polygon (at least v 1.54, v1.55 and previous) in very rare cases crashes
+    // when using 16 segments to approximate a circle.
+    // So using 18 segments is a workaround to try to avoid these crashes
+    // ( We already used this trick in plot_board_layers.cpp,
+    // see PlotSolderMaskLayer() )
+    const int       segcountforcircle   = 18;
     double          correctionFactor    = 1.0 / cos( M_PI / (segcountforcircle * 2) );
     const int       segcountLowQuality  = 12;   // segments to draw a circle with low quality
                                                 // to reduce time calculations
@@ -355,11 +360,13 @@ void EDA_3D_CANVAS::BuildBoard3DView()
                 LAYER_NUM       zonelayer = zone->GetLayer();
 
                 if( zonelayer == layer )
+                {
                     zone->TransformSolidAreasShapesToPolygonSet(
                         hightQualityMode ? bufferPolys : bufferZonesPolys,
                         segcountLowQuality, correctionFactorLQ );
                 }
             }
+        }
 
         // draw graphic items on copper layers (texts)
         for( BOARD_ITEM* item = pcb->m_Drawings; item; item = item->Next() )

pcbnew/dialogs/dialog_plot.cpp

@@ -46,8 +46,6 @@ DIALOG_PLOT::DIALOG_PLOT( PCB_EDIT_FRAME* aParent ) :
     m_plotOpts( aParent->GetPlotSettings() )
 {
     m_config = Kiface().KifaceSettings();
-    m_brdSettings = m_board->GetDesignSettings();
-
     Init_Dialog();
 
     GetSizer()->Fit( this );
@@ -101,9 +99,9 @@ void DIALOG_PLOT::Init_Dialog()
         break;
     }
 
-    msg = StringFromValue( g_UserUnit, m_brdSettings.m_SolderMaskMargin, true );
+    msg = StringFromValue( g_UserUnit, m_board->GetDesignSettings().m_SolderMaskMargin, true );
     m_SolderMaskMarginCurrValue->SetLabel( msg );
-    msg = StringFromValue( g_UserUnit, m_brdSettings.m_SolderMaskMinWidth, true );
+    msg = StringFromValue( g_UserUnit, m_board->GetDesignSettings().m_SolderMaskMinWidth, true );
     m_SolderMaskMinWidthCurrValue->SetLabel( msg );
 
     // Set units and value for HPGL pen size (this param in in mils).

pcbnew/dialogs/dialog_plot.h

@@ -41,7 +41,6 @@ public:
 private:
     PCB_EDIT_FRAME*     m_parent;
     BOARD*              m_board;
-    BOARD_DESIGN_SETTINGS  m_brdSettings;
     wxConfigBase*       m_config;
     std::vector<LAYER_NUM> m_layerList;                // List to hold CheckListBox layer numbers
     double              m_XScaleAdjust;             // X scale factor adjust to compensate

polygon/PolyLine.cpp

@@ -1222,7 +1222,7 @@ int CPolyLine::HitTestForCorner( const wxPoint& aPos, int aDistMax ) const
  * Copy the contours to a KI_POLYGON_WITH_HOLES
  * The first contour is the main outline, others are holes
  */
-void CPOLYGONS_LIST::ExportTo( KI_POLYGON_WITH_HOLES& aPolygoneWithHole )
+void CPOLYGONS_LIST::ExportTo( KI_POLYGON_WITH_HOLES& aPolygoneWithHole ) const
 {
     unsigned    corners_count = m_cornersList.size();
 
@@ -1273,7 +1273,7 @@ void CPOLYGONS_LIST::ExportTo( KI_POLYGON_WITH_HOLES& aPolygoneWithHole )
  * Each contour is copied into a KI_POLYGON, and each KI_POLYGON
  * is append to aPolygons
  */
-void CPOLYGONS_LIST::ExportTo( KI_POLYGON_SET& aPolygons )
+void CPOLYGONS_LIST::ExportTo( KI_POLYGON_SET& aPolygons ) const
 {
     std::vector<KI_POLY_POINT> cornerslist;
     unsigned    corners_count = GetCornersCount();

polygon/PolyLine.h

@@ -164,7 +164,7 @@ public:
      * Copy all contours to a KI_POLYGON_SET
      * @param aPolygons = the KI_POLYGON_WITH_HOLES to populate
      */
-    void    ExportTo( KI_POLYGON_SET& aPolygons );
+    void    ExportTo( KI_POLYGON_SET& aPolygons ) const;
 
     /**
      * Function ExportTo
@@ -172,7 +172,7 @@ public:
      * The first contour is the main outline, others are holes
      * @param aPolygoneWithHole = the KI_POLYGON_WITH_HOLES to populate
      */
-    void    ExportTo( KI_POLYGON_WITH_HOLES& aPolygoneWithHole );
+    void    ExportTo( KI_POLYGON_WITH_HOLES& aPolygoneWithHole ) const;
 
     /**
      * Function ImportFrom