From b97587cab398dbc25b6ff1b9f8ca3fcbe7781416 Mon Sep 17 00:00:00 2001
From: "MA-LAPTOP\\apeltauer" <manuel.apeltauer@direkt.net>
Date: Mon, 10 Aug 2020 09:14:49 +0200
Subject: [PATCH] Improve the projection on surface algorithm. For now the
 first possible solution was taken. If several solution exists, this leads to
 a miss match. Now check the distance of the projection shape and the original
 shape and the take the projection with the smallest distance. Discussion can
 be found here:
 https://forum.freecadweb.org/viewtopic.php?f=8&t=49341&p=422925#p422925

---
 src/Mod/Part/Gui/DlgProjectionOnSurface.cpp | 31 ++++++++++++++++++---
 1 file changed, 27 insertions(+), 4 deletions(-)

diff --git a/src/Mod/Part/Gui/DlgProjectionOnSurface.cpp b/src/Mod/Part/Gui/DlgProjectionOnSurface.cpp
index cbfc57d023..e61e7431fa 100644
--- a/src/Mod/Part/Gui/DlgProjectionOnSurface.cpp
+++ b/src/Mod/Part/Gui/DlgProjectionOnSurface.cpp
@@ -45,6 +45,7 @@
 # include <BRepPrimAPI_MakePrism.hxx>
 # include <gp_Ax1.hxx>
 # include <BRepBuilderAPI_Transform.hxx>
+#include <BRepExtrema_DistShapeShape.hxx>
 #endif
 
 #include "DlgProjectionOnSurface.h"
@@ -452,16 +453,38 @@ void PartGui::DlgProjectionOnSurface::create_projection_wire(std::vector<SShapeS
         for (auto itWire : itCurrentShape.aWireVec)
         {
           BRepProj_Projection aProjection(itWire, itCurrentShape.surfaceToProject, itCurrentShape.aProjectionDir);
-          auto currentProjection = aProjection.Shape();
-          auto aWire = sort_and_heal_wire(currentProjection, itCurrentShape.surfaceToProject);
+          double minDistance = std::numeric_limits<double>::max();
+          TopoDS_Wire wireToTake;
+          for ( ; aProjection.More(); aProjection.Next() )
+          {
+            auto it = aProjection.Current();
+            BRepExtrema_DistShapeShape distanceMeasure(it, itCurrentShape.aFace);
+            distanceMeasure.Perform();
+            auto currentDistance = distanceMeasure.Value();
+            if ( currentDistance > minDistance ) continue;
+            wireToTake = it;
+            minDistance = currentDistance;
+          }
+          auto aWire = sort_and_heal_wire(wireToTake, itCurrentShape.surfaceToProject);
           itCurrentShape.aProjectedWireVec.push_back(aWire);
         }
       }
       else if (!itCurrentShape.aEdge.IsNull())
       {
         BRepProj_Projection aProjection(itCurrentShape.aEdge, itCurrentShape.surfaceToProject, itCurrentShape.aProjectionDir);
-        auto currentProjection = aProjection.Shape();
-        for (TopExp_Explorer aExplorer(currentProjection, TopAbs_EDGE); aExplorer.More(); aExplorer.Next())
+        double minDistance = std::numeric_limits<double>::max();
+        TopoDS_Wire wireToTake;
+        for (; aProjection.More(); aProjection.Next())
+        {
+          auto it = aProjection.Current();
+          BRepExtrema_DistShapeShape distanceMeasure(it, itCurrentShape.aEdge);
+          distanceMeasure.Perform();
+          auto currentDistance = distanceMeasure.Value();
+          if (currentDistance > minDistance) continue;
+          wireToTake = it;
+          minDistance = currentDistance;
+        }
+        for (TopExp_Explorer aExplorer(wireToTake, TopAbs_EDGE); aExplorer.More(); aExplorer.Next())
         {
           itCurrentShape.aProjectedEdgeVec.push_back(TopoDS::Edge(aExplorer.Current()));
         }