quick try to get PhysicalRegion to work in MathEval... To test ;-)

Plugin/MathEval.cpp

@@ -8,6 +8,7 @@
 #include "MathEval.h"
 #include "mathEvaluator.h"
 #include "OctreePost.h"
+#include "GEntity.h"
 
 StringXNumber MathEvalOptions_Number[] = {
   {GMSH_FULLRC, "TimeStep", NULL, -1.},
@@ -96,7 +97,7 @@ PView *GMSH_MathEvalPlugin::execute(PView *view)
   int otherTimeStep = (int)MathEvalOptions_Number[2].def;
   int iOtherView = (int)MathEvalOptions_Number[3].def;
   int forceInterpolation = (int)MathEvalOptions_Number[4].def;
-  int region = (int)MathEvalOptions_Number[5].def;
+  int physicalRegion = (int)MathEvalOptions_Number[5].def;
   std::vector<std::string> expr(9);
   for(int i = 0; i < 9; i++) expr[i] = MathEvalOptions_String[i].def;
 
@@ -185,7 +186,16 @@ PView *GMSH_MathEvalPlugin::execute(PView *view)
   int timeBeg = (timeStep < 0) ? firstNonEmptyStep : timeStep;
   int timeEnd = (timeStep < 0) ? -timeStep : timeStep + 1;
   for(int ent = 0; ent < data1->getNumEntities(timeBeg); ent++){
-    if (region>0 && (ent+1)!=region) continue;
+    bool ok = (physicalRegion <= 0);
+    if(physicalRegion > 0){
+      GEntity *ge = data1->getEntity(timeBeg, ent);
+      if(ge){
+        std::vector<int>::iterator it = std::find
+          (ge->physicals.begin(), ge->physicals.end(), physicalRegion);
+        ok = (it != ge->physicals.end());
+      }
+    }
+    if(!ok) continue;
     for(int ele = 0; ele < data1->getNumElements(timeBeg, ent); ele++){
       if(data1->skipElement(timeBeg, ent, ele)) continue;
       int numNodes = data1->getNumNodes(timeBeg, ent, ele);

Post/PViewData.cpp

@@ -95,10 +95,22 @@ void PViewData::setValue(int step, int ent, int ele, int nod, int comp, double v
   Msg::Error("Cannot change field value in this view");
 }
 
+GModel *PViewData::getModel(int step)
+{
+  Msg::Error("Cannot get entity from this view");
+  return 0;
+}
+
+GEntity *PViewData::getEntity(int step, int ent)
+{
+  Msg::Error("Cannot get entity from this view");
+  return 0;
+}
+
 MElement *PViewData::getElement(int step, int ent, int ele)
 {
   Msg::Error("Cannot get element from this view");
-  return NULL;
+  return 0;
 }
 
 void PViewData::setInterpolationMatrices(int type,

Post/PViewData.h

@@ -222,6 +222,12 @@ class PViewData {
   virtual bool isRemote(){ return false; }
   virtual int fillRemoteVertexArrays(std::string &options){ return 0; }
 
+  // get GModel (if view supports it)
+  virtual GModel *getModel(int step);
+
+  // get GEntity (if view supports it)
+  virtual GEntity *getEntity(int step, int entity);
+
   // get MElement (if view supports it)
   virtual MElement *getElement(int step, int entity, int element);
 

Post/PViewDataGModel.cpp

@@ -441,6 +441,11 @@ int PViewDataGModel::getNumElements(int step, int ent)
   return _steps[step]->getEntity(ent)->getNumMeshElements();
 }
 
+GEntity *PViewDataGModel::getEntity(int step, int ent)
+{
+  return _steps[step]->getEntity(ent);
+}
+
 MElement *PViewDataGModel::getElement(int step, int ent, int element)
 {
   if(_steps.empty()) return 0;
@@ -770,11 +775,6 @@ bool PViewDataGModel::hasModel(GModel *model, int step)
   return (model == _steps[step]->getModel());
 }
 
-GEntity *PViewDataGModel::getEntity(int step, int ent)
-{
-  return _steps[step]->getEntity(ent);
-}
-
 bool PViewDataGModel::getValueByIndex(int step, int dataIndex, int nod, int comp, double &val)
 {
   double *d = _steps[step]->getData(dataIndex);

Post/PViewDataGModel.h

@@ -220,17 +220,14 @@ class PViewDataGModel : public PViewData {
   bool hasMultipleMeshes();
   bool hasModel(GModel *model, int step=-1);
   bool useGaussPoints(){ return _type == GaussPointData; }
+  GModel* getModel(int step){ return _steps[step]->getModel(); }
+  GEntity *getEntity(int step, int ent);
+  MElement *getElement(int step, int entity, int element);
 
   // get the data type
   DataType getType(){ return _type; }
-  // direct access to GModel entities
-  GEntity *getEntity(int step, int ent);
   // direct access to value by index
   bool getValueByIndex(int step, int dataIndex, int node, int comp, double &val);
-  // get underlying model
-  GModel* getModel(int step){ return _steps[step]->getModel(); }
-  // get MElement
-  MElement *getElement(int step, int entity, int element);
 
   // Add some data "on the fly" (data is stored in a map, indexed by
   // node or element number depending on the type of dataset)