From 3ae8d4550638f863c07838cb9c8a67e76fb8123d Mon Sep 17 00:00:00 2001
From: marioalexis <mario.passaglia@gmail.com>
Date: Tue, 24 Feb 2026 01:33:43 -0300
Subject: [PATCH] Fem: Read material info from .frd file

---
 src/Mod/Fem/App/FemVTKTools.cpp               | 23 +++++++++++++++----
 src/Mod/Fem/Gui/ViewProviderFemPostObject.cpp |  9 ++++----
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/src/Mod/Fem/App/FemVTKTools.cpp b/src/Mod/Fem/App/FemVTKTools.cpp
index 61f9311814..bce77e57f9 100644
--- a/src/Mod/Fem/App/FemVTKTools.cpp
+++ b/src/Mod/Fem/App/FemVTKTools.cpp
@@ -33,6 +33,7 @@
 #include <SMESH_Mesh.hxx>
 
 #include <vtkCellArray.h>
+#include <vtkCellData.h>
 #include <vtkDataArray.h>
 #include <vtkDataSetReader.h>
 #include <vtkDataSetWriter.h>
@@ -1177,7 +1178,7 @@ void valueFromLine<double>(const std::string_view::iterator& it, int digits, dou
 
 // add cell from sorted nodes
 template<typename T>
-void addCell(vtkSmartPointer<vtkCellArray>& cellArray, const std::vector<int>& topoElem)
+void addCell(vtkCellArray* cellArray, const std::vector<int>& topoElem)
 {
     vtkSmartPointer<T> cell = vtkSmartPointer<T>::New();
     cell->GetPointIds()->SetNumberOfIds(topoElem.size());
@@ -1190,7 +1191,7 @@ void addCell(vtkSmartPointer<vtkCellArray>& cellArray, const std::vector<int>& t
 
 // fill cell array
 void fillCell(
-    vtkSmartPointer<vtkCellArray>& cellArray,
+    vtkCellArray* cellArray,
     std::vector<int>& topoElem,
     std::vector<int>& vtkType,
     ElementType elemType
@@ -1363,7 +1364,9 @@ std::vector<int> readElements(
     std::ifstream& ifstr,
     const std::string& lines,
     const std::map<int, int>& mapNodes,
-    vtkSmartPointer<vtkCellArray>& cellArray
+    vtkCellArray* cellArray,
+    vtkIntArray* material,
+    vtkIntArray* group
 )
 {
     std::string line;
@@ -1380,6 +1383,12 @@ std::vector<int> readElements(
     std::vector<int> topoElem;
     std::vector<int> vtkType;
 
+    material->SetNumberOfComponents(1);
+    material->SetName("Material");
+
+    group->SetNumberOfComponents(1);
+    group->SetName("Group");
+
     std::string_view view {lines};
 
     std::string_view sub = view.substr(keyCode.length() + 18);
@@ -1412,6 +1421,8 @@ std::vector<int> readElements(
             // add cell to cellArray
             if (topoElem.size() == mapCcxTypeNodes[static_cast<ElementType>(info[0])]) {
                 fillCell(cellArray, topoElem, vtkType, static_cast<ElementType>(info[0]));
+                group->InsertNextValue(info[1]);
+                material->InsertNextValue(info[2]);
                 topoElem.clear();
                 mapElem[elem] = elemID++;
             }
@@ -1657,6 +1668,8 @@ vtkSmartPointer<vtkMultiBlockDataSet> readFRD(std::ifstream& ifstr)
     std::string line;
     std::map<int, int> mapNodes;
     std::vector<int> cellTypes;
+    auto materialArray = vtkSmartPointer<vtkIntArray>::New();
+    auto groupArray = vtkSmartPointer<vtkIntArray>::New();
 
     while (std::getline(ifstr, line)) {
         std::string keyCode = "    2C";
@@ -1669,7 +1682,7 @@ vtkSmartPointer<vtkMultiBlockDataSet> readFRD(std::ifstream& ifstr)
         keyCode = "    3C";
         if (view.rfind(keyCode, 0) == 0) {
             // read elements block
-            cellTypes = readElements(ifstr, line, mapNodes, cells);
+            cellTypes = readElements(ifstr, line, mapNodes, cells, materialArray, groupArray);
         }
         keyCode = "    1P";
         if (view.rfind(keyCode, 0) == 0) {
@@ -1699,6 +1712,8 @@ vtkSmartPointer<vtkMultiBlockDataSet> readFRD(std::ifstream& ifstr)
                 grid = vtkSmartPointer<vtkUnstructuredGrid>::New();
                 grid->SetPoints(points);
                 grid->SetCells(cellTypes.data(), cells);
+                grid->GetCellData()->AddArray(materialArray);
+                grid->GetCellData()->AddArray(groupArray);
 
                 // create TimeValue metadata
                 auto stepValue = createTimeValue(info.value);
diff --git a/src/Mod/Fem/Gui/ViewProviderFemPostObject.cpp b/src/Mod/Fem/Gui/ViewProviderFemPostObject.cpp
index 034513abce..24b8116114 100644
--- a/src/Mod/Fem/Gui/ViewProviderFemPostObject.cpp
+++ b/src/Mod/Fem/Gui/ViewProviderFemPostObject.cpp
@@ -433,10 +433,11 @@ void ViewProviderFemPostObject::updateProperties()
         }
     }
 
-    vtkCellData* cell = poly->GetCellData();
-    for (int i = 0; i < cell->GetNumberOfArrays(); ++i) {
-        colorArrays.emplace_back(cell->GetArrayName(i));
-    }
+    // don't add cell data arrays until they are supported in the 3d view
+    // vtkCellData* cell = poly->GetCellData();
+    // for (int i = 0; i < cell->GetNumberOfArrays(); ++i) {
+    //    colorArrays.emplace_back(cell->GetArrayName(i));
+    //}
 
     App::Enumeration empty;
     Field.setValue(empty);