fixed crash in enabling shading for polydata widgets

modules/viz/src/clouds.cpp

@@ -313,7 +313,7 @@ cv::viz::WMesh::WMesh(const Mesh3d &mesh)
     cell_array->Squeeze();
     polydata->SetStrips(cell_array);
 
-    vtkSmartPointer<vtkDataSetMapper> mapper = vtkSmartPointer<vtkDataSetMapper>::New();
+    vtkSmartPointer<vtkPolyDataMapper> mapper = vtkSmartPointer<vtkPolyDataMapper>::New();
     mapper->SetScalarModeToUsePointData();
     mapper->ImmediateModeRenderingOff();
     VtkUtils::SetInputData(mapper, polydata);

modules/viz/src/precomp.hpp

@@ -220,6 +220,22 @@ namespace cv
                 scalars->SetArray(color_data->val, size * 3, 0);
                 return scalars;
             }
+
+            static vtkSmartPointer<vtkPolyData> ComputeNormals(vtkSmartPointer<vtkPolyData> polydata)
+            {
+                vtkSmartPointer<vtkPolyDataNormals> normals_generator = vtkSmartPointer<vtkPolyDataNormals>::New();
+                normals_generator->ComputePointNormalsOn();
+                normals_generator->ComputeCellNormalsOff();
+                normals_generator->SetFeatureAngle(0.1);
+                normals_generator->SetSplitting(0);
+                normals_generator->SetConsistency(1);
+                normals_generator->SetAutoOrientNormals(0);
+                normals_generator->SetFlipNormals(0);
+                normals_generator->SetNonManifoldTraversal(1);
+                VtkUtils::SetInputData(normals_generator, polydata);
+                normals_generator->Update();
+                return normals_generator->GetOutput();
+            }
         };
 
         inline vtkSmartPointer<vtkMatrix4x4> vtkmatrix(const cv::Matx44d &matrix)

modules/viz/src/vizcore.cpp

@@ -285,21 +285,9 @@ void cv::viz::writeTrajectory(InputArray _traj, const String& files_format, int
 void cv::viz::computeNormals(const Mesh3d& mesh, OutputArray _normals)
 {
     vtkSmartPointer<vtkPolyData> polydata = getPolyData(WMesh(mesh));
+    vtkSmartPointer<vtkPolyData> with_normals = VtkUtils::ComputeNormals(polydata);
 
-    vtkSmartPointer<vtkPolyDataNormals> normal_generator = vtkSmartPointer<vtkPolyDataNormals>::New();
-    normal_generator->SetInputConnection(polydata->GetProducerPort());
-    normal_generator->ComputePointNormalsOn();
-    normal_generator->ComputeCellNormalsOff();
-
-    normal_generator->SetFeatureAngle(0.1);
-    normal_generator->SetSplitting(0);
-    normal_generator->SetConsistency(1);
-    normal_generator->SetAutoOrientNormals(0);
-    normal_generator->SetFlipNormals(0);
-    normal_generator->SetNonManifoldTraversal(1);
-    normal_generator->Update();
-
-    vtkSmartPointer<vtkDataArray> generic_normals = normal_generator->GetOutput()->GetPointData()->GetNormals();
+    vtkSmartPointer<vtkDataArray> generic_normals = with_normals->GetPointData()->GetNormals();
     if(generic_normals)
     {
         Mat normals(1, generic_normals->GetNumberOfTuples(), CV_64FC3);

modules/viz/src/widget.cpp

@@ -141,10 +141,10 @@ void cv::viz::Widget::setRenderingProperty(int property, double value)
                     if (!actor->GetMapper()->GetInput()->GetPointData()->GetNormals())
                     {
                         vtkSmartPointer<vtkPolyDataMapper> mapper = vtkPolyDataMapper::SafeDownCast(actor->GetMapper());
-                        vtkSmartPointer<vtkPolyDataNormals> normals = vtkSmartPointer<vtkPolyDataNormals>::New();
-                        VtkUtils::SetInputData(normals, mapper->GetInput());
-                        normals->Update();
-                        VtkUtils::SetInputData(mapper, normals->GetOutput());
+                        CV_Assert("Can't set shading property for such type of widget" && mapper);
+
+                        vtkSmartPointer<vtkPolyData> with_normals = VtkUtils::ComputeNormals(mapper->GetInput());
+                        VtkUtils::SetInputData(mapper, with_normals);
                     }
                     actor->GetProperty()->SetInterpolationToGouraud();
                     break;
@@ -154,10 +154,10 @@ void cv::viz::Widget::setRenderingProperty(int property, double value)
                     if (!actor->GetMapper()->GetInput()->GetPointData()->GetNormals())
                     {
                         vtkSmartPointer<vtkPolyDataMapper> mapper = vtkPolyDataMapper::SafeDownCast(actor->GetMapper());
-                        vtkSmartPointer<vtkPolyDataNormals> normals = vtkSmartPointer<vtkPolyDataNormals>::New();
-                        VtkUtils::SetInputData(normals, mapper->GetInput());
-                        normals->Update();
-                        VtkUtils::SetInputData(mapper, normals->GetOutput());
+                        CV_Assert("Can't set shading property for such type of widget" && mapper);
+
+                        vtkSmartPointer<vtkPolyData> with_normals = VtkUtils::ComputeNormals(mapper->GetInput());
+                        VtkUtils::SetInputData(mapper, with_normals);
                     }
                     actor->GetProperty()->SetInterpolationToPhong();
                     break;