Merge branch 'fix/vtkExtras' into 'master'

Fix/vtk extras

See merge request nektar/nektar!925

(cherry picked from commit 158ebf21)

4e41d63e updated VtkToPng to account for deprecation of OpenGL in VTK
1ee2b968 accounting for legacy behavior in
2ae87c1f update changelog
eeccccb0 modify vtkExtras to account for multiple versions
f76e1e45 moved from 4.4.1 to 4.4.2 in changelog

CHANGELOG.md

@@ -29,6 +29,9 @@ v4.4.2
 **FieldConvert**
 - Allow passing input name with trailing separator (!879)
 
+**Utilities**
+- Fix VtkToPng to account for deprecated VTK API for VTK version > 8.1 (!925)
+
 v4.4.1
 ------
 **Library**

utilities/Extras/VtkToPng.cpp

@@ -102,7 +102,12 @@ int main(int argc, char * argv[])
 #else
     mapper->SetInputData(data);
 #endif
+
+#if VTK_MAJOR_VERSION < 8 || (VTK_MAJOR_VERSION == 8 && VTK_MINOR_VERSION <= 1)
+    //deprecated as of vtk 8.1
     mapper->ImmediateModeRenderingOn();
+#endif
+    
     mapper->ScalarVisibilityOn();
     mapper->SetScalarModeToUsePointData();
     mapper->UseLookupTableScalarRangeOn();
@@ -139,7 +144,13 @@ int main(int argc, char * argv[])
     vtkSmartPointer<vtkWindowToImageFilter> windowToImageFilter =
             vtkSmartPointer<vtkWindowToImageFilter>::New();
     windowToImageFilter->SetInput(renderWindow);
+
+#if VTK_MAJOR_VERSION < 8 || (VTK_MAJOR_VERSION == 8 && VTK_MINOR_VERSION <= 1)
+    //deprecated as of vtk 8.1
     windowToImageFilter->SetMagnification(4);
+#else
+    windowToImageFilter->SetScale(4, 4);
+#endif
     windowToImageFilter->Update();
 
     // Write image to PNG