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#878 Segmentation fault when setting distance on the two same points
[modules/shaper.git] / src / SketchPlugin / SketchPlugin_ConstraintFillet.cpp
index 79cac01e7d10411a328c68a2db727a9f3eb7e2ae..6cf6da8f669062a579482109de07df6828394d46 100644 (file)
@@ -17,6 +17,7 @@
 #include <ModelAPI_Events.h>
 #include <ModelAPI_ResultConstruction.h>
 #include <ModelAPI_Session.h>
+#include <ModelAPI_Validator.h>
 
 #include <SketchPlugin_Arc.h>
 #include <SketchPlugin_Line.h>
 #include <Config_PropManager.h>
 #include <Events_Loop.h>
 
+#include <math.h>
+
+static const std::string PREVIOUS_VALUE("FilletPreviousRadius");
+
 /// \brief Attract specified point on theNewArc to the attribute of theFeature
 static void recalculateAttributes(FeaturePtr theNewArc, const std::string& theNewArcAttribute,
   FeaturePtr theFeature, const std::string& theFeatureAttribute);
 
+/// \brief Calculates center of fillet arc and coordinates of tangency points
+static void calculateFilletCenter(FeaturePtr theFeatureA, FeaturePtr theFeatureB,
+                                  double theRadius, bool theNotInversed[2],
+                                  std::shared_ptr<GeomAPI_XY>& theCenter,
+                                  std::shared_ptr<GeomAPI_XY>& theTangentA,
+                                  std::shared_ptr<GeomAPI_XY>& theTangentB);
+
 
 SketchPlugin_ConstraintFillet::SketchPlugin_ConstraintFillet()
 {
@@ -45,12 +57,21 @@ void SketchPlugin_ConstraintFillet::initAttributes()
   data()->addAttribute(SketchPlugin_Constraint::ENTITY_A(), ModelAPI_AttributeRefAttr::typeId());
   data()->addAttribute(SketchPlugin_Constraint::ENTITY_B(), ModelAPI_AttributeRefAttr::typeId());
   data()->addAttribute(SketchPlugin_Constraint::ENTITY_C(), ModelAPI_AttributeRefList::typeId());
+  data()->addAttribute(PREVIOUS_VALUE, ModelAPI_AttributeDouble::typeId());
   // initialize attribute not applicable for user
-  data()->attribute(SketchPlugin_Constraint::ENTITY_C())->setInitialized();
+  ModelAPI_Session::get()->validators()->registerNotObligatory(getKind(), SketchPlugin_Constraint::ENTITY_C());
+  data()->attribute(PREVIOUS_VALUE)->setInitialized();
+  std::dynamic_pointer_cast<ModelAPI_AttributeDouble>(data()->attribute(PREVIOUS_VALUE))->setValue(0.0);
 }
 
 void SketchPlugin_ConstraintFillet::execute()
 {
+  // the viewer update should be blocked in order to avoid the temporaty fillet sub-features visualization
+  // before they are processed by the solver
+  //std::shared_ptr<Events_Message> aMsg = std::shared_ptr<Events_Message>(
+  //    new Events_Message(Events_Loop::eventByName(EVENT_UPDATE_VIEWER_BLOCKED)));
+  //Events_Loop::loop()->send(aMsg);
+
   std::shared_ptr<ModelAPI_Data> aData = data();
   ResultConstructionPtr aRC;
   // Check the base objects are initialized
@@ -66,34 +87,8 @@ void SketchPlugin_ConstraintFillet::execute()
   // Check the fillet shapes is not initialized yet
   AttributeRefListPtr aRefListOfFillet = std::dynamic_pointer_cast<ModelAPI_AttributeRefList>(
       aData->attribute(SketchPlugin_Constraint::ENTITY_C()));
-  if (aRefListOfFillet->size() > 0) {
-    // update the Radius constraint
-    ObjectPtr aFilletArcObj = aRefListOfFillet->list().back();
-    aRC = std::dynamic_pointer_cast<ModelAPI_ResultConstruction>(aFilletArcObj);
-    FeaturePtr aFilletArcFeature = aRC ? aRC->document()->feature(aRC) : 
-      std::dynamic_pointer_cast<ModelAPI_Feature>(aFilletArcObj);
+  bool needNewObjects = aRefListOfFillet->size() == 0;
 
-    int aNbSubs = sketch()->numberOfSubs();
-    FeaturePtr aSubFeature;
-    for (int aSub = 0; aSub < aNbSubs; aSub++) {
-      aSubFeature = sketch()->subFeature(aSub);
-      if (aSubFeature->getKind() != SketchPlugin_ConstraintRadius::ID())
-        continue;
-      AttributeRefAttrPtr aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
-          aSubFeature->attribute(SketchPlugin_Constraint::ENTITY_A()));
-      if (!aRefAttr || !aRefAttr->isObject())
-        continue;
-      aRC = std::dynamic_pointer_cast<ModelAPI_ResultConstruction>(aRefAttr->object());
-      FeaturePtr aFeature = aRC ? aRC->document()->feature(aRC) : 
-        std::dynamic_pointer_cast<ModelAPI_Feature>(aRefAttr->object());
-      if (aFeature == aFilletArcFeature) {
-        AttributeDoublePtr aRadius = std::dynamic_pointer_cast<ModelAPI_AttributeDouble>(
-            aSubFeature->attribute(SketchPlugin_Constraint::VALUE()));
-        aRadius->setValue(aFilletRadius);
-      }
-    }
-    return;
-  }
   // Obtain features for the base objects
   FeaturePtr aFeatureA, aFeatureB;
   aRC = std::dynamic_pointer_cast<ModelAPI_ResultConstruction>(aBaseA->object());
@@ -103,41 +98,38 @@ void SketchPlugin_ConstraintFillet::execute()
   if (!aFeatureA || !aFeatureB)
     return;
 
-  // Create list of objects composing a fillet
-  // copy aFeatureA
-  FeaturePtr aNewFeatureA = sketch()->addFeature(aFeatureA->getKind());
-  aFeatureA->data()->copyTo(aNewFeatureA->data());
-  aNewFeatureA->execute();
-  aRefListOfFillet->append(aNewFeatureA);
-  // copy aFeatureB
-  FeaturePtr aNewFeatureB = sketch()->addFeature(aFeatureB->getKind());
-  aFeatureB->data()->copyTo(aNewFeatureB->data());
-  aNewFeatureB->execute();
-  aRefListOfFillet->append(aNewFeatureB);
-  // create filleting arc
-  FeaturePtr aNewArc = sketch()->addFeature(SketchPlugin_Arc::ID());
-  aRefListOfFillet->append(aNewArc);
-  aRefListOfFillet->setInitialized();
-
-  // Wait all constraints being created, then send update events
-  static Events_ID anUpdateEvent = Events_Loop::eventByName(EVENT_OBJECT_UPDATED);
-  bool isUpdateFlushed = Events_Loop::loop()->isFlushed(anUpdateEvent);
-  if (isUpdateFlushed)
-    Events_Loop::loop()->setFlushed(anUpdateEvent, false);
+  FeaturePtr aNewFeatureA, aNewFeatureB, aNewArc;
+  if (needNewObjects) {
+    // Create list of objects composing a fillet
+    // copy aFeatureA
+    aNewFeatureA = SketchPlugin_Sketch::addUniqueNamedCopiedFeature(aFeatureA, sketch());
+    // copy aFeatureB
+    aNewFeatureB = SketchPlugin_Sketch::addUniqueNamedCopiedFeature(aFeatureB, sketch());
+    // create filleting arc (it will be attached to the list later)
+    aNewArc = sketch()->addFeature(SketchPlugin_Arc::ID());
+  } else {
+    // Obtain features from the list
+    std::list<ObjectPtr> aNewFeatList = aRefListOfFillet->list();
+    std::list<ObjectPtr>::iterator aFeatIt = aNewFeatList.begin();
+    aNewFeatureA = ModelAPI_Feature::feature(*aFeatIt++);
+    aNewFeatureB = ModelAPI_Feature::feature(*aFeatIt++);
+    aNewArc = ModelAPI_Feature::feature(*aFeatIt);
+  }
 
   // Calculate arc attributes
   static const int aNbFeatures = 2;
-  FeaturePtr aFeature[aNbFeatures] = {aNewFeatureA, aNewFeatureB};
+  FeaturePtr aFeature[aNbFeatures] = {aFeatureA, aFeatureB};
+  FeaturePtr aNewFeature[aNbFeatures] = {aNewFeatureA, aNewFeatureB};
   std::shared_ptr<GeomAPI_Dir2d> aTangentDir[aNbFeatures]; // tangent directions of the features in coincident point
   bool isStart[aNbFeatures]; // indicates which point the features share
   std::shared_ptr<GeomAPI_Pnt2d> aStartEndPnt[aNbFeatures * 2]; // first pair of points relate to first feature, second pair -  to second
   std::string aFeatAttributes[aNbFeatures * 2]; // attributes of features
   for (int i = 0; i < aNbFeatures; i++) {
     std::string aStartAttr, aEndAttr;
-    if (aFeature[i]->getKind() == SketchPlugin_Line::ID()) {
+    if (aNewFeature[i]->getKind() == SketchPlugin_Line::ID()) {
       aStartAttr = SketchPlugin_Line::START_ID();
       aEndAttr = SketchPlugin_Line::END_ID();
-    } else if (aFeature[i]->getKind() == SketchPlugin_Arc::ID()) {
+    } else if (aNewFeature[i]->getKind() == SketchPlugin_Arc::ID()) {
       aStartAttr = SketchPlugin_Arc::START_ID();
       aEndAttr = SketchPlugin_Arc::END_ID();
     } else { // wrong argument
@@ -167,14 +159,14 @@ void SketchPlugin_ConstraintFillet::execute()
   // tangent directions of the features
   for (int i = 0; i < aNbFeatures; i++) {
     std::shared_ptr<GeomAPI_XY> aDir;
-    if (aFeature[i]->getKind() == SketchPlugin_Line::ID()) {
+    if (aNewFeature[i]->getKind() == SketchPlugin_Line::ID()) {
       aDir = aStartEndPnt[2*i+1]->xy()->decreased(aStartEndPnt[2*i]->xy());
       if (!isStart[i])
         aDir = aDir->multiplied(-1.0);
-    } else if (aFeature[i]->getKind() == SketchPlugin_Arc::ID()) {
+    } else if (aNewFeature[i]->getKind() == SketchPlugin_Arc::ID()) {
       std::shared_ptr<GeomAPI_Pnt2d> aCenterPoint =
           std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-          aFeature[i]->attribute(SketchPlugin_Arc::CENTER_ID()))->pnt();
+          aNewFeature[i]->attribute(SketchPlugin_Arc::CENTER_ID()))->pnt();
       aDir = isStart[i] ? aStartEndPnt[2*i]->xy() : aStartEndPnt[2*i+1]->xy();
       aDir = aDir->decreased(aCenterPoint->xy());
 
@@ -187,103 +179,197 @@ void SketchPlugin_ConstraintFillet::execute()
     }
     aTangentDir[i] = std::shared_ptr<GeomAPI_Dir2d>(new GeomAPI_Dir2d(aDir));
   }
+
+  // Wait all constraints being created, then send update events
+  static Events_ID anUpdateEvent = Events_Loop::eventByName(EVENT_OBJECT_UPDATED);
+  bool isUpdateFlushed = Events_Loop::loop()->isFlushed(anUpdateEvent);
+  if (isUpdateFlushed)
+    Events_Loop::loop()->setFlushed(anUpdateEvent, false);
+
   // By default, the start point of fillet arc is connected to FeatureA,
   // and the end point - to FeatureB. But when the angle between TangentDirA and
   // TangentDirB greater 180 degree, the sequaence of features need to be reversed.
   double cosBA = aTangentDir[0]->cross(aTangentDir[1]); // cos(B-A), where A and B - angles between corresponding tanget direction and the X axis
   bool isReversed = cosBA > 0.0;
 
-  std::shared_ptr<GeomAPI_Pnt2d> aSharedPoint = aStartEndPnt[isStart[0] ? 0 : 1];
-  std::shared_ptr<GeomAPI_Dir2d> aBisect(new GeomAPI_Dir2d(
-      aTangentDir[0]->xy()->added(aTangentDir[1]->xy())));
-  std::shared_ptr<GeomAPI_XY> aStep = aBisect->xy()->multiplied(aFilletRadius);
-  std::shared_ptr<GeomAPI_XY> aCenter = aSharedPoint->xy()->added(aStep);
+  // Calculate fillet arc parameters
+  std::shared_ptr<GeomAPI_XY> aCenter, aTangentPntA, aTangentPntB;
+  calculateFilletCenter(aFeatureA, aFeatureB, aFilletRadius, isStart, aCenter, aTangentPntA, aTangentPntB);
+  // update features
+  std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
+      aNewFeatureA->attribute(aFeatAttributes[isStart[0] ? 0 : 1]))->setValue(
+      aTangentPntA->x(), aTangentPntA->y());
+  aNewFeatureA->execute();
+  std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
+      aNewFeatureB->attribute(aFeatAttributes[2 + (isStart[1] ? 0 : 1)]))->setValue(
+      aTangentPntB->x(), aTangentPntB->y());
+  aNewFeatureB->execute();
+  // update fillet arc
   std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
       aNewArc->attribute(SketchPlugin_Arc::CENTER_ID()))->setValue(
       aCenter->x(), aCenter->y());
+  if (isReversed) {
+    std::shared_ptr<GeomAPI_XY> aTmp = aTangentPntA;
+    aTangentPntA = aTangentPntB;
+    aTangentPntB = aTmp;
+  }
   std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-      aNewArc->attribute(SketchPlugin_Arc::START_ID()))->setValue(
-      aCenter->x() - aStep->y(), aCenter->y() + aStep->x());
+      aNewArc->attribute(SketchPlugin_Arc::START_ID()))->setValue(aTangentPntA->x(), aTangentPntA->y());
   std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-      aNewArc->attribute(SketchPlugin_Arc::END_ID()))->setValue(
-      aCenter->x() + aStep->y(), aCenter->y() - aStep->x());
+      aNewArc->attribute(SketchPlugin_Arc::END_ID()))->setValue(aTangentPntB->x(), aTangentPntB->y());
   aNewArc->execute();
 
-  // Create list of additional constraints:
-  // 1. Coincidence of boundary points of features and fillet arc
-  // 1.1. coincidence
-  FeaturePtr aConstraint = sketch()->addFeature(SketchPlugin_ConstraintCoincidence::ID());
-  AttributeRefAttrPtr aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
-      aConstraint->attribute(SketchPlugin_Constraint::ENTITY_A()));
-  aRefAttr->setAttr(aNewArc->attribute(SketchPlugin_Arc::START_ID()));
-  aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
-      aConstraint->attribute(SketchPlugin_Constraint::ENTITY_B()));
-  int aFeatInd = isReversed ? 1 : 0;
-  int anAttrInd = (isReversed ? 2 : 0) + (isStart[isReversed ? 1 : 0] ? 0 : 1);
-  aRefAttr->setAttr(aFeature[aFeatInd]->attribute(aFeatAttributes[anAttrInd]));
-  recalculateAttributes(aNewArc, SketchPlugin_Arc::START_ID(), aFeature[aFeatInd], aFeatAttributes[anAttrInd]);
-  aConstraint->execute();
-  ModelAPI_EventCreator::get()->sendUpdated(aConstraint, anUpdateEvent);
-  // 1.2. coincidence
-  aConstraint = sketch()->addFeature(SketchPlugin_ConstraintCoincidence::ID());
-  aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
-      aConstraint->attribute(SketchPlugin_Constraint::ENTITY_A()));
-  aRefAttr->setAttr(aNewArc->attribute(SketchPlugin_Arc::END_ID()));
-  aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
-      aConstraint->attribute(SketchPlugin_Constraint::ENTITY_B()));
-  aFeatInd = isReversed ? 0 : 1;
-  anAttrInd = (isReversed ? 0 : 2) + (isStart[isReversed ? 0 : 1] ? 0 : 1);
-  aRefAttr->setAttr(aFeature[aFeatInd]->attribute(aFeatAttributes[anAttrInd]));
-  recalculateAttributes(aNewArc, SketchPlugin_Arc::END_ID(), aFeature[aFeatInd], aFeatAttributes[anAttrInd]);
-  aConstraint->execute();
-  ModelAPI_EventCreator::get()->sendUpdated(aConstraint, anUpdateEvent);
-  // recalculate center of fillet arc
-  std::shared_ptr<GeomAPI_Pnt2d> aStartPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-      aNewArc->attribute(SketchPlugin_Arc::START_ID()))->pnt();
-  std::shared_ptr<GeomAPI_Pnt2d> aEndPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-      aNewArc->attribute(SketchPlugin_Arc::END_ID()))->pnt();
-  aCenter = aStartPoint->xy()->added(aEndPoint->xy())->multiplied(0.5);
-  std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-      aNewArc->attribute(SketchPlugin_Arc::CENTER_ID()))->setValue(
-      aCenter->x(), aCenter->y());
-  // 2. Fillet arc radius
-  aConstraint = sketch()->addFeature(SketchPlugin_ConstraintRadius::ID());
-  aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
-      aConstraint->attribute(SketchPlugin_Constraint::ENTITY_A()));
-  aRefAttr->setObject(aNewArc->lastResult());
-  std::dynamic_pointer_cast<ModelAPI_AttributeDouble>(
-      aConstraint->attribute(SketchPlugin_Constraint::VALUE()))->setValue(aFilletRadius);
-  std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-      aConstraint->attribute(SketchPlugin_Constraint::FLYOUT_VALUE_PNT()))->setValue(
-      isStart[0] ? aStartEndPnt[0] : aStartEndPnt[1]);
-  aConstraint->execute();
-  ModelAPI_EventCreator::get()->sendUpdated(aConstraint, anUpdateEvent);
-  // 3. Tangency of fillet arc and features
-  for (int i = 0; i < aNbFeatures; i++) {
-    aConstraint = sketch()->addFeature(SketchPlugin_ConstraintTangent::ID());
+  if (needNewObjects) {
+    // attach new arc to the list
+    aRefListOfFillet->append(aNewFeatureA->lastResult());
+    aRefListOfFillet->append(aNewFeatureB->lastResult());
+    aRefListOfFillet->append(aNewArc->lastResult());
+
+    myProducedFeatures.push_back(aNewFeatureA);
+    myProducedFeatures.push_back(aNewFeatureB);
+    myProducedFeatures.push_back(aNewArc);
+
+    // Create list of additional constraints:
+    // 1. Coincidence of boundary points of features (copied lines/arcs) and fillet arc
+    // 1.1. coincidence
+    FeaturePtr aConstraint = sketch()->addFeature(SketchPlugin_ConstraintCoincidence::ID());
+    AttributeRefAttrPtr aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+        aConstraint->attribute(SketchPlugin_Constraint::ENTITY_A()));
+    aRefAttr->setAttr(aNewArc->attribute(SketchPlugin_Arc::START_ID()));
+    aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+        aConstraint->attribute(SketchPlugin_Constraint::ENTITY_B()));
+    int aFeatInd = isReversed ? 1 : 0;
+    int anAttrInd = (isReversed ? 2 : 0) + (isStart[isReversed ? 1 : 0] ? 0 : 1);
+    aRefAttr->setAttr(aNewFeature[aFeatInd]->attribute(aFeatAttributes[anAttrInd]));
+    recalculateAttributes(aNewArc, SketchPlugin_Arc::START_ID(), aNewFeature[aFeatInd], aFeatAttributes[anAttrInd]);
+    aConstraint->execute();
+    myProducedFeatures.push_back(aConstraint);
+    ModelAPI_EventCreator::get()->sendUpdated(aConstraint, anUpdateEvent);
+    // 1.2. coincidence
+    aConstraint = sketch()->addFeature(SketchPlugin_ConstraintCoincidence::ID());
     aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
         aConstraint->attribute(SketchPlugin_Constraint::ENTITY_A()));
-    aRefAttr->setObject(aNewArc->lastResult());
+    aRefAttr->setAttr(aNewArc->attribute(SketchPlugin_Arc::END_ID()));
     aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
         aConstraint->attribute(SketchPlugin_Constraint::ENTITY_B()));
-    bool isArc = aFeature[i]->getKind() == SketchPlugin_Arc::ID();
-    aRefAttr->setObject(isArc ? aFeature[i]->lastResult() : aFeature[i]->firstResult());
+    aFeatInd = isReversed ? 0 : 1;
+    anAttrInd = (isReversed ? 0 : 2) + (isStart[isReversed ? 0 : 1] ? 0 : 1);
+    aRefAttr->setAttr(aNewFeature[aFeatInd]->attribute(aFeatAttributes[anAttrInd]));
+    recalculateAttributes(aNewArc, SketchPlugin_Arc::END_ID(), aNewFeature[aFeatInd], aFeatAttributes[anAttrInd]);
+    aConstraint->execute();
+    myProducedFeatures.push_back(aConstraint);
+    ModelAPI_EventCreator::get()->sendUpdated(aConstraint, anUpdateEvent);
+    // 2. Fillet arc radius
+    aConstraint = sketch()->addFeature(SketchPlugin_ConstraintRadius::ID());
+    aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+        aConstraint->attribute(SketchPlugin_Constraint::ENTITY_A()));
+    aRefAttr->setObject(aNewArc->lastResult());
+    std::dynamic_pointer_cast<ModelAPI_AttributeDouble>(
+        aConstraint->attribute(SketchPlugin_Constraint::VALUE()))->setValue(aFilletRadius);
+    std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
+        aConstraint->attribute(SketchPlugin_Constraint::FLYOUT_VALUE_PNT()))->setValue(
+        isStart[0] ? aStartEndPnt[0] : aStartEndPnt[1]);
     aConstraint->execute();
+    myProducedFeatures.push_back(aConstraint);
     ModelAPI_EventCreator::get()->sendUpdated(aConstraint, anUpdateEvent);
+    // 3. Tangency of fillet arc and features
+    for (int i = 0; i < aNbFeatures; i++) {
+      aConstraint = sketch()->addFeature(SketchPlugin_ConstraintTangent::ID());
+      aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+          aConstraint->attribute(SketchPlugin_Constraint::ENTITY_A()));
+      aRefAttr->setObject(aNewArc->lastResult());
+      aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+          aConstraint->attribute(SketchPlugin_Constraint::ENTITY_B()));
+      bool isArc = aNewFeature[i]->getKind() == SketchPlugin_Arc::ID();
+      aRefAttr->setObject(isArc ? aNewFeature[i]->lastResult() : aNewFeature[i]->firstResult());
+      aConstraint->execute();
+      myProducedFeatures.push_back(aConstraint);
+      ModelAPI_EventCreator::get()->sendUpdated(aConstraint, anUpdateEvent);
+    }
+    // 4. Coincidence of free boundaries of base and copied features
+    for (int i = 0; i < aNbFeatures; i++) {
+      anAttrInd = 2*i + (isStart[i] ? 1 : 0);
+      aConstraint = sketch()->addFeature(SketchPlugin_ConstraintCoincidence::ID());
+      aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+          aConstraint->attribute(SketchPlugin_Constraint::ENTITY_A()));
+      aRefAttr->setAttr(aFeature[i]->attribute(aFeatAttributes[anAttrInd]));
+      aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+          aConstraint->attribute(SketchPlugin_Constraint::ENTITY_B()));
+      aRefAttr->setAttr(aNewFeature[i]->attribute(aFeatAttributes[anAttrInd]));
+      myProducedFeatures.push_back(aConstraint);
+    }
+    // 5. Tangent points should be placed on the base features
+    for (int i = 0; i < aNbFeatures; i++) {
+      anAttrInd = 2*i + (isStart[i] ? 0 : 1);
+      aConstraint = sketch()->addFeature(SketchPlugin_ConstraintCoincidence::ID());
+      aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+          aConstraint->attribute(SketchPlugin_Constraint::ENTITY_A()));
+      aRefAttr->setAttr(aNewFeature[i]->attribute(aFeatAttributes[anAttrInd]));
+      aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+          aConstraint->attribute(SketchPlugin_Constraint::ENTITY_B()));
+      aRefAttr->setObject(aFeature[i]->lastResult());
+      myProducedFeatures.push_back(aConstraint);
+    }
+    // make base features auxiliary
+    aFeatureA->boolean(SketchPlugin_SketchEntity::AUXILIARY_ID())->setValue(true);
+    aFeatureB->boolean(SketchPlugin_SketchEntity::AUXILIARY_ID())->setValue(true);
+    myBaseObjects.clear();
+    myBaseObjects.push_back(aFeatureA);
+    myBaseObjects.push_back(aFeatureB);
+  } else {
+    // Update radius value
+    int aNbSubs = sketch()->numberOfSubs();
+    FeaturePtr aSubFeature;
+    for (int aSub = 0; aSub < aNbSubs; aSub++) {
+      aSubFeature = sketch()->subFeature(aSub);
+      if (aSubFeature->getKind() != SketchPlugin_ConstraintRadius::ID())
+        continue;
+      AttributeRefAttrPtr aRefAttr = std::dynamic_pointer_cast<ModelAPI_AttributeRefAttr>(
+          aSubFeature->attribute(SketchPlugin_Constraint::ENTITY_A()));
+      if (!aRefAttr || !aRefAttr->isObject())
+        continue;
+      FeaturePtr aFeature = ModelAPI_Feature::feature(aRefAttr->object());
+      if (aFeature == aNewArc) {
+        AttributeDoublePtr aRadius = std::dynamic_pointer_cast<ModelAPI_AttributeDouble>(
+          aSubFeature->attribute(SketchPlugin_Constraint::VALUE()));
+        aRadius->setValue(aFilletRadius);
+        break;
+      }
+    }
   }
 
-  // make base features auxiliary
-  static Events_ID aRedisplayEvent = Events_Loop::eventByName(EVENT_OBJECT_TO_REDISPLAY);
-  aFeatureA->boolean(SketchPlugin_SketchEntity::AUXILIARY_ID())->setValue(true);
-  aFeatureB->boolean(SketchPlugin_SketchEntity::AUXILIARY_ID())->setValue(true);
-  ModelAPI_EventCreator::get()->sendUpdated(aFeatureA, aRedisplayEvent);
-  ModelAPI_EventCreator::get()->sendUpdated(aFeatureB, aRedisplayEvent);
-////  Events_Loop::loop()->flush(aRedisplayEvent);
-
-  // send events
+  // send events to update the sub-features by the solver
   if (isUpdateFlushed)
     Events_Loop::loop()->setFlushed(anUpdateEvent, true);
-  Events_Loop::loop()->flush(anUpdateEvent);
+
+  // the viewer update should be unblocked in order after the fillet features
+  // are processed by the solver
+  //aMsg = std::shared_ptr<Events_Message>(
+  //              new Events_Message(Events_Loop::eventByName(EVENT_UPDATE_VIEWER_UNBLOCKED)));
+  //Events_Loop::loop()->send(aMsg);
+}
+
+void SketchPlugin_ConstraintFillet::attributeChanged(const std::string& theID)
+{
+  if (theID == SketchPlugin_Constraint::ENTITY_A() ||
+      theID == SketchPlugin_Constraint::ENTITY_B()) {
+    // clear the list of fillet entities
+    AttributeRefListPtr aRefListOfFillet = std::dynamic_pointer_cast<ModelAPI_AttributeRefList>(
+        data()->attribute(SketchPlugin_Constraint::ENTITY_C()));
+    aRefListOfFillet->clear();
+
+    // remove all produced objects and constraints
+    DocumentPtr aDoc = sketch()->document();
+    std::list<FeaturePtr>::iterator aCIt = myProducedFeatures.begin();
+    for (; aCIt != myProducedFeatures.end(); ++aCIt)
+      aDoc->removeFeature(*aCIt);
+    myProducedFeatures.clear();
+
+    // clear auxiliary flag on initial objects
+    for (aCIt = myBaseObjects.begin(); aCIt != myBaseObjects.end(); ++aCIt)
+      (*aCIt)->boolean(SketchPlugin_SketchEntity::AUXILIARY_ID())->setValue(false);
+    myBaseObjects.clear();
+  }
 }
 
 AISObjectPtr SketchPlugin_ConstraintFillet::getAISObject(AISObjectPtr thePrevious)
@@ -296,42 +382,267 @@ AISObjectPtr SketchPlugin_ConstraintFillet::getAISObject(AISObjectPtr thePreviou
   return anAIS;
 }
 
+bool SketchPlugin_ConstraintFillet::isMacro() const
+{
+  return true;
+}
 
 
 // =========   Auxiliary functions   =================
 void recalculateAttributes(FeaturePtr theNewArc,  const std::string& theNewArcAttribute,
-                            FeaturePtr theFeature, const std::string& theFeatureAttribute)
+                           FeaturePtr theFeature, const std::string& theFeatureAttribute)
 {
   std::shared_ptr<GeomAPI_Pnt2d> anArcPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
       theNewArc->attribute(theNewArcAttribute))->pnt();
-  if (theFeature->getKind() == SketchPlugin_Line::ID()) {
-    std::shared_ptr<GeomAPI_Pnt2d> aStartPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-        theFeature->attribute(SketchPlugin_Line::START_ID()))->pnt();
-    std::shared_ptr<GeomAPI_Pnt2d> aEndPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-        theFeature->attribute(SketchPlugin_Line::END_ID()))->pnt();
-    std::shared_ptr<GeomAPI_Dir2d> aLineDir(new GeomAPI_Dir2d(
-        aEndPoint->xy()->decreased(aStartPoint->xy())));
-    std::shared_ptr<GeomAPI_XY> aVec = anArcPoint->xy()->decreased(aStartPoint->xy());
-    double aDot = aVec->dot(aLineDir->xy());
-    aVec = aStartPoint->xy()->added(aLineDir->xy()->multiplied(aDot));
-    anArcPoint->setX(aVec->x());
-    anArcPoint->setY(aVec->y());
-  } else if (theFeature->getKind() == SketchPlugin_Arc::ID()) {
-    std::shared_ptr<GeomAPI_Pnt2d> aStartPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-        theFeature->attribute(SketchPlugin_Arc::START_ID()))->pnt();
-    std::shared_ptr<GeomAPI_Pnt2d> aCenterPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-        theFeature->attribute(SketchPlugin_Arc::END_ID()))->pnt();
-    double aRadius = aStartPoint->distance(aCenterPoint);
-    std::shared_ptr<GeomAPI_Dir2d> aDir(new GeomAPI_Dir2d(
-        anArcPoint->xy()->decreased(aCenterPoint->xy())));
-    std::shared_ptr<GeomAPI_XY> aPoint = aCenterPoint->xy()->added(aDir->xy()->multiplied(aRadius));
-    anArcPoint->setX(aPoint->x());
-    anArcPoint->setY(aPoint->y());
-  } else
-    return;
-
-  std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
-      theNewArc->attribute(theNewArcAttribute))->setValue(anArcPoint->x(), anArcPoint->y());
   std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
       theFeature->attribute(theFeatureAttribute))->setValue(anArcPoint->x(), anArcPoint->y());
 }
+
+/// \brief Find intersections of lines shifted along normal direction
+void possibleFilletCenterLineLine(
+    std::shared_ptr<GeomAPI_XY> thePointA, std::shared_ptr<GeomAPI_Dir2d> theDirA,
+    std::shared_ptr<GeomAPI_XY> thePointB, std::shared_ptr<GeomAPI_Dir2d> theDirB,
+    double theRadius, std::list< std::shared_ptr<GeomAPI_XY> >& theCenters)
+{
+  std::shared_ptr<GeomAPI_Dir2d> aDirAT(new GeomAPI_Dir2d(-theDirA->y(), theDirA->x()));
+  std::shared_ptr<GeomAPI_Dir2d> aDirBT(new GeomAPI_Dir2d(-theDirB->y(), theDirB->x()));
+  std::shared_ptr<GeomAPI_XY> aPntA, aPntB;
+  double aDet = theDirA->cross(theDirB);
+  for (double aStepA = -1.0; aStepA <= 1.0; aStepA += 2.0) {
+    aPntA = thePointA->added(aDirAT->xy()->multiplied(aStepA * theRadius));
+    for (double aStepB = -1.0; aStepB <= 1.0; aStepB += 2.0) {
+      aPntB = thePointB->added(aDirBT->xy()->multiplied(aStepB * theRadius));
+      double aVX = aDirAT->xy()->dot(aPntA);
+      double aVY = aDirBT->xy()->dot(aPntB);
+      std::shared_ptr<GeomAPI_XY> aPoint(new GeomAPI_XY(
+          (theDirB->x() * aVX - theDirA->x() * aVY) / aDet,
+          (theDirB->y() * aVX - theDirA->y() * aVY) / aDet));
+      theCenters.push_back(aPoint);
+    }
+  }
+}
+
+/// \brief Find intersections of line shifted along normal direction in both sides
+///        and a circle with extended radius
+void possibleFilletCenterLineArc(
+    std::shared_ptr<GeomAPI_XY> theStartLine, std::shared_ptr<GeomAPI_Dir2d> theDirLine,
+    std::shared_ptr<GeomAPI_XY> theCenterArc, double theRadiusArc,
+    double theRadius, std::list< std::shared_ptr<GeomAPI_XY> >& theCenters)
+{
+  std::shared_ptr<GeomAPI_Dir2d> aDirT(new GeomAPI_Dir2d(-theDirLine->y(), theDirLine->x()));
+  std::shared_ptr<GeomAPI_XY> aPnt;
+  double aDirNorm2 = theDirLine->dot(theDirLine);
+  double aRad = 0.0;
+  double aDirX = theDirLine->x();
+  double aDirX2 = theDirLine->x() * theDirLine->x();
+  double aDirY2 = theDirLine->y() * theDirLine->y();
+  double aDirXY = theDirLine->x() * theDirLine->y();
+  for (double aStepA = -1.0; aStepA <= 1.0; aStepA += 2.0) {
+    aPnt = theStartLine->added(aDirT->xy()->multiplied(aStepA * theRadius));
+    double aCoeff = aDirT->xy()->dot(aPnt->decreased(theCenterArc));
+    double aCoeff2 = aCoeff * aCoeff;
+    for (double aStepB = -1.0; aStepB <= 1.0; aStepB += 2.0) {
+      aRad = theRadiusArc + aStepB * theRadius;
+      double aD = aRad * aRad * aDirNorm2 - aCoeff2;
+      if (aD < 0.0)
+        continue;
+      double aDs = sqrt(aD);
+      double x1 = theCenterArc->x() + (aCoeff * aDirT->x() - aDirT->y() * aDs) / aDirNorm2;
+      double x2 = theCenterArc->x() + (aCoeff * aDirT->x() + aDirT->y() * aDs) / aDirNorm2;
+      double y1 = (aDirX2 * aPnt->y() + aDirY2 * theCenterArc->y() -
+          aDirXY * (aPnt->x() - theCenterArc->x()) - theDirLine->y() * aDs) / aDirNorm2;
+      double y2 = (aDirX2 * aPnt->y() + aDirY2 * theCenterArc->y() -
+          aDirXY * (aPnt->x() - theCenterArc->x()) + theDirLine->y() * aDs) / aDirNorm2;
+
+      std::shared_ptr<GeomAPI_XY> aPoint1(new GeomAPI_XY(x1, y1));
+      theCenters.push_back(aPoint1);
+      std::shared_ptr<GeomAPI_XY> aPoint2(new GeomAPI_XY(x2, y2));
+      theCenters.push_back(aPoint2);
+    }
+  }
+}
+
+/// \brief Find intersections of two circles with extended radii
+void possibleFilletCenterArcArc(
+    std::shared_ptr<GeomAPI_XY> theCenterA, double theRadiusA,
+    std::shared_ptr<GeomAPI_XY> theCenterB, double theRadiusB,
+    double theRadius, std::list< std::shared_ptr<GeomAPI_XY> >& theCenters)
+{
+  std::shared_ptr<GeomAPI_XY> aCenterDir = theCenterB->decreased(theCenterA);
+  double aCenterDist2 = aCenterDir->dot(aCenterDir);
+  double aCenterDist = sqrt(aCenterDist2);
+
+  double aRadA, aRadB;
+  for (double aStepA = -1.0; aStepA <= 1.0; aStepA += 2.0) {
+    aRadA = theRadiusA + aStepA * theRadius;
+    for (double aStepB = -1.0; aStepB <= 1.0; aStepB += 2.0) {
+      aRadB = theRadiusB + aStepB * theRadius;
+      if (aRadA + aRadB < aCenterDist || fabs(aRadA - aRadB) > aCenterDist)
+        continue; // there is no intersections
+
+      double aMedDist = (aRadA * aRadA - aRadB * aRadB + aCenterDist2) / (2.0 * aCenterDist);
+      double aHeight = sqrt(aRadA * aRadA - aMedDist * aMedDist);
+
+      double x1 = theCenterA->x() + (aMedDist * aCenterDir->x() + aCenterDir->y() * aHeight) / aCenterDist;
+      double y1 = theCenterA->y() + (aMedDist * aCenterDir->y() - aCenterDir->x() * aHeight) / aCenterDist;
+
+      double x2 = theCenterA->x() + (aMedDist * aCenterDir->x() - aCenterDir->y() * aHeight) / aCenterDist;
+      double y2 = theCenterA->y() + (aMedDist * aCenterDir->y() + aCenterDir->x() * aHeight) / aCenterDist;
+
+      std::shared_ptr<GeomAPI_XY> aPoint1(new GeomAPI_XY(x1, y1));
+      theCenters.push_back(aPoint1);
+      std::shared_ptr<GeomAPI_XY> aPoint2(new GeomAPI_XY(x2, y2));
+      theCenters.push_back(aPoint2);
+    }
+  }
+}
+
+void calculateFilletCenter(FeaturePtr theFeatureA, FeaturePtr theFeatureB,
+                           double theRadius, bool theNotInversed[2],
+                           std::shared_ptr<GeomAPI_XY>& theCenter,
+                           std::shared_ptr<GeomAPI_XY>& theTangentA,
+                           std::shared_ptr<GeomAPI_XY>& theTangentB)
+{
+  static const int aNbFeatures = 2;
+  FeaturePtr aFeature[aNbFeatures] = {theFeatureA, theFeatureB};
+  std::shared_ptr<GeomAPI_XY> aStart[aNbFeatures], aEnd[aNbFeatures], aCenter[aNbFeatures];
+  std::shared_ptr<GeomDataAPI_Point2D> aStartPoint, aEndPoint;
+
+  for (int i = 0; i < aNbFeatures; i++) {
+    if (aFeature[i]->getKind() == SketchPlugin_Line::ID()) {
+      aStartPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
+          aFeature[i]->attribute(SketchPlugin_Line::START_ID()));
+      aEndPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
+          aFeature[i]->attribute(SketchPlugin_Line::END_ID()));
+    } else if (aFeature[i]->getKind() == SketchPlugin_Arc::ID()) {
+      aStartPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
+          aFeature[i]->attribute(SketchPlugin_Arc::START_ID()));
+      aEndPoint = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
+          aFeature[i]->attribute(SketchPlugin_Arc::END_ID()));
+      aCenter[i] = std::dynamic_pointer_cast<GeomDataAPI_Point2D>(
+          aFeature[i]->attribute(SketchPlugin_Arc::CENTER_ID()))->pnt()->xy();
+    } else
+      return;
+    aStart[i] = std::shared_ptr<GeomAPI_XY>(theNotInversed[i] ?
+        new GeomAPI_XY(aStartPoint->x(), aStartPoint->y()) :
+        new GeomAPI_XY(aEndPoint->x(), aEndPoint->y()));
+    aEnd[i] = std::shared_ptr<GeomAPI_XY>(theNotInversed[i] ?
+        new GeomAPI_XY(aEndPoint->x(), aEndPoint->y()) :
+        new GeomAPI_XY(aStartPoint->x(), aStartPoint->y()));
+  }
+
+  if (theFeatureA->getKind() == SketchPlugin_Line::ID() &&
+      theFeatureB->getKind() == SketchPlugin_Line::ID()) {
+    std::shared_ptr<GeomAPI_Dir2d> aDir[2];
+    std::shared_ptr<GeomAPI_Dir2d> aDirT[2];
+    for (int i = 0; i < aNbFeatures; i++) {
+      aDir[i] = std::shared_ptr<GeomAPI_Dir2d>(new GeomAPI_Dir2d(aEnd[i]->decreased(aStart[i])));
+      aDirT[i] = std::shared_ptr<GeomAPI_Dir2d>(new GeomAPI_Dir2d(-aDir[i]->y(), aDir[i]->x()));
+    }
+
+    // get and filter possible centers
+    std::list< std::shared_ptr<GeomAPI_XY> > aSuspectCenters;
+    possibleFilletCenterLineLine(aStart[0], aDir[0], aStart[1], aDir[1], theRadius, aSuspectCenters);
+    double aDot = 0.0;
+    std::list< std::shared_ptr<GeomAPI_XY> >::iterator anIt = aSuspectCenters.begin();
+    for (; anIt != aSuspectCenters.end(); anIt++) {
+      aDot = aDirT[0]->xy()->dot(aStart[0]->decreased(*anIt));
+      theTangentA = (*anIt)->added(aDirT[0]->xy()->multiplied(aDot));
+      if (theTangentA->decreased(aStart[0])->dot(aDir[0]->xy()) < 0.0)
+        continue; // incorrect position
+      aDot = aDirT[1]->xy()->dot(aStart[1]->decreased(*anIt));
+      theTangentB = (*anIt)->added(aDirT[1]->xy()->multiplied(aDot));
+      if (theTangentB->decreased(aStart[1])->dot(aDir[1]->xy()) < 0.0)
+        continue; // incorrect position
+      // the center is found, stop searching
+      theCenter = *anIt;
+      return;
+    }
+  } else if ((theFeatureA->getKind() == SketchPlugin_Arc::ID() &&
+      theFeatureB->getKind() == SketchPlugin_Line::ID()) || 
+      (theFeatureA->getKind() == SketchPlugin_Line::ID() &&
+      theFeatureB->getKind() == SketchPlugin_Arc::ID())) {
+    int aLineInd = theFeatureA->getKind() == SketchPlugin_Line::ID() ? 0 : 1;
+    double anArcRadius = aStart[1-aLineInd]->distance(aCenter[1-aLineInd]);
+    std::shared_ptr<GeomAPI_Dir2d> aDirLine = std::shared_ptr<GeomAPI_Dir2d>(
+        new GeomAPI_Dir2d(aEnd[aLineInd]->decreased(aStart[aLineInd])));
+    std::shared_ptr<GeomAPI_Dir2d> aDirT = std::shared_ptr<GeomAPI_Dir2d>(
+        new GeomAPI_Dir2d(-aDirLine->y(), aDirLine->x()));
+
+    std::shared_ptr<GeomAPI_Dir2d> aStartArcDir = std::shared_ptr<GeomAPI_Dir2d>(
+        new GeomAPI_Dir2d(aStart[1-aLineInd]->decreased(aCenter[1-aLineInd])));
+    std::shared_ptr<GeomAPI_Dir2d> aEndArcDir = std::shared_ptr<GeomAPI_Dir2d>(
+        new GeomAPI_Dir2d(aEnd[1-aLineInd]->decreased(aCenter[1-aLineInd])));
+    double anArcAngle = aEndArcDir->angle(aStartArcDir);
+
+    // get and filter possible centers
+    std::list< std::shared_ptr<GeomAPI_XY> > aSuspectCenters;
+    possibleFilletCenterLineArc(aStart[aLineInd], aDirLine, aCenter[1-aLineInd], anArcRadius, theRadius, aSuspectCenters);
+    double aDot = 0.0;
+    std::shared_ptr<GeomAPI_XY> aLineTgPoint, anArcTgPoint;
+    std::list< std::shared_ptr<GeomAPI_XY> >::iterator anIt = aSuspectCenters.begin();
+    for (; anIt != aSuspectCenters.end(); anIt++) {
+      aDot = aDirT->xy()->dot(aStart[aLineInd]->decreased(*anIt));
+      aLineTgPoint = (*anIt)->added(aDirT->xy()->multiplied(aDot));
+      if (aLineTgPoint->decreased(aStart[aLineInd])->dot(aDirLine->xy()) < 0.0)
+        continue; // incorrect position
+      std::shared_ptr<GeomAPI_Dir2d> aCurDir = std::shared_ptr<GeomAPI_Dir2d>(
+          new GeomAPI_Dir2d((*anIt)->decreased(aCenter[1-aLineInd])));
+      double aCurAngle = aCurDir->angle(aStartArcDir);
+      if (anArcAngle < 0.0) aCurAngle *= -1.0;
+      if (aCurAngle < 0.0 || aCurAngle > fabs(anArcAngle))
+        continue; // incorrect position
+      // the center is found, stop searching
+      theCenter = *anIt;
+      anArcTgPoint = aCenter[1-aLineInd]->added(aCurDir->xy()->multiplied(anArcRadius));
+      if (theFeatureA->getKind() == SketchPlugin_Line::ID()) {
+        theTangentA = aLineTgPoint;
+        theTangentB = anArcTgPoint;
+      } else {
+        theTangentA = anArcTgPoint;
+        theTangentB = aLineTgPoint;
+      }
+      return;
+    }
+  } else if (theFeatureA->getKind() == SketchPlugin_Arc::ID() &&
+      theFeatureB->getKind() == SketchPlugin_Arc::ID()) {
+    double anArcRadius[aNbFeatures];
+    double anArcAngle[aNbFeatures];
+    std::shared_ptr<GeomAPI_Dir2d> aStartArcDir[aNbFeatures];
+    for (int i = 0; i < aNbFeatures; i++) {
+      anArcRadius[i] = aStart[i]->distance(aCenter[i]);
+      aStartArcDir[i] = std::shared_ptr<GeomAPI_Dir2d>(
+          new GeomAPI_Dir2d(aStart[i]->decreased(aCenter[i])));
+      std::shared_ptr<GeomAPI_Dir2d> aEndArcDir = std::shared_ptr<GeomAPI_Dir2d>(
+          new GeomAPI_Dir2d(aEnd[i]->decreased(aCenter[i])));
+      anArcAngle[i] = aEndArcDir->angle(aStartArcDir[i]);
+    }
+
+    // get and filter possible centers
+    std::list< std::shared_ptr<GeomAPI_XY> > aSuspectCenters;
+    possibleFilletCenterArcArc(aCenter[0], anArcRadius[0], aCenter[1], anArcRadius[1], theRadius, aSuspectCenters);
+    double aDot = 0.0;
+    std::shared_ptr<GeomAPI_XY> aLineTgPoint, anArcTgPoint;
+    std::list< std::shared_ptr<GeomAPI_XY> >::iterator anIt = aSuspectCenters.begin();
+    for (; anIt != aSuspectCenters.end(); anIt++) {
+      std::shared_ptr<GeomAPI_Dir2d> aCurDir = std::shared_ptr<GeomAPI_Dir2d>(
+          new GeomAPI_Dir2d((*anIt)->decreased(aCenter[0])));
+      double aCurAngle = aCurDir->angle(aStartArcDir[0]);
+      if (anArcAngle[0] < 0.0) aCurAngle *= -1.0;
+      if (aCurAngle < 0.0 || aCurAngle > fabs(anArcAngle[0]))
+        continue; // incorrect position
+      theTangentA = aCenter[0]->added(aCurDir->xy()->multiplied(anArcRadius[0]));
+
+      aCurDir = std::shared_ptr<GeomAPI_Dir2d>(new GeomAPI_Dir2d((*anIt)->decreased(aCenter[1])));
+      aCurAngle = aCurDir->angle(aStartArcDir[1]);
+      if (anArcAngle[1] < 0.0) aCurAngle *= -1.0;
+      if (aCurAngle < 0.0 || aCurAngle > fabs(anArcAngle[1]))
+        continue; // incorrect position
+      theTangentB = aCenter[1]->added(aCurDir->xy()->multiplied(anArcRadius[1]));
+
+      // the center is found, stop searching
+      theCenter = *anIt;
+      return;
+    }
+  }
+}