fixing a compositing issue and never set the radius to 0 (#205)

* fixing a compositing issue and never set the radius to 0

* account for an empty data set for clipping

* add a test for rendering particles with no data

src/tests/vtkh/t_vtk-h_point_renderer.cpp

@@ -9,6 +9,7 @@
 #include <vtkh/vtkh.hpp>
 #include <vtkh/DataSet.hpp>
 #include <vtkh/rendering/PointRenderer.hpp>
+#include <vtkh/filters/MarchingCubes.hpp>
 #include <vtkh/rendering/Scene.hpp>
 #include "t_test_utils.hpp"
 
@@ -82,6 +83,59 @@ TEST(vtkh_point_renderer, vtkh_variable_point_render)
 
 
 
+  vtkh::Scene scene;
+  scene.AddRenderer(&renderer);
+  scene.AddRender(render);
+  scene.Render();
+
+}
+
+TEST(vtkh_point_renderer, vtkh_point_no_data)
+{
+  vtkh::DataSet data_set;
+
+  const int base_size = 16;
+  const int num_blocks = 2;
+
+  for(int i = 0; i < num_blocks; ++i)
+  {
+    data_set.AddDomain(CreateTestData(i, num_blocks, base_size), i);
+  }
+  vtkh::MarchingCubes marcher;
+  marcher.SetInput(&data_set);
+  marcher.SetField("point_data_Float64");
+
+  const int num_vals = 1;
+  double iso_vals [num_vals];
+  iso_vals[0] = -1; // ask for something that does not exist
+
+  marcher.SetIsoValues(iso_vals, num_vals);
+  marcher.AddMapField("point_data_Float64");
+  marcher.AddMapField("cell_data_Float64");
+  marcher.Update();
+
+  vtkh::DataSet *iso_output = marcher.GetOutput();
+  data_set = *iso_output;
+  delete iso_output;
+
+  vtkm::Bounds bounds = data_set.GetGlobalBounds();
+
+  vtkm::rendering::Camera camera;
+  camera.ResetToBounds(bounds);
+  camera.SetPosition(vtkm::Vec<vtkm::Float64,3>(16, 36, -36));
+  vtkh::Render render = vtkh::MakeRender(512,
+                                         512,
+                                         camera,
+                                         data_set,
+                                         "render_no_data");
+  vtkh::PointRenderer renderer;
+  renderer.SetInput(&data_set);
+  renderer.SetField("point_data_Float64");
+  renderer.UseVariableRadius(true);
+  renderer.SetRadiusDelta(1.0f);
+
+
+
   vtkh::Scene scene;
   scene.AddRenderer(&renderer);
   scene.AddRender(render);

src/vtkh/DataSet.cpp

@@ -102,8 +102,8 @@ void MemSet(vtkm::cont::ArrayHandle<T> &array, const T value, const vtkm::Id num
 bool
 DataSet::OneDomainPerRank() const
 {
-  bool at_least_one = GetNumberOfDomains() < 2;
-  return detail::GlobalAgreement(at_least_one);
+  bool one = GetNumberOfDomains() == 1;
+  return detail::GlobalAgreement(one);
 }
 
 void

src/vtkh/filters/Clip.cpp

@@ -305,6 +305,17 @@ void Clip::DoExecute()
 {
 
   DataSet data_set;
+  const int global_domains = this->m_input->GetGlobalNumberOfDomains();
+  if(global_domains == 0)
+  {
+    // if the number of domains zero there is no work to do,
+    // additionally, a multiplane clip will fail since it will
+    // check if 'mclip_field' will exist, which it wont.
+    DataSet *output = new DataSet();
+    *output = *(this->m_input);
+    this->m_output = output;
+    return;
+  }
   const int num_domains = this->m_input->GetNumberOfDomains();
   // we now have to work around this since
   // vtkm dropped support for new implicit functions

src/vtkh/rendering/PointRenderer.cpp

@@ -116,6 +116,11 @@ PointRenderer::PreExecute()
     // same as used in vtk ospray
     constexpr vtkm::Float64 heuristic = 1000.;
     radius = static_cast<vtkm::Float32>(mag / heuristic);
+    // we likely have a data set with no cells so just set some radius
+    if(radius == 0.f)
+    {
+      radius = 0.00001f;
+    }
     mesh_mapper->SetRadius(radius);
   }
 

src/vtkh/rendering/VolumeRenderer.cpp

@@ -470,6 +470,7 @@ VolumeRenderer::DoExecute()
 {
   if(m_input->OneDomainPerRank() && !m_has_unstructured)
   {
+    // Danger: this logic only works if there is exactly one per rank
     RenderOneDomainPerRank();
   }
   else