wire up scalar rendering fields option

CHANGELOG.md

@@ -25,6 +25,7 @@ and this project aspires to adhere to [Semantic Versioning](https://semver.org/s
 - Added `add_mpi_ranks` and `add_domain_ids` filters for adding rank and domain fields to a mesh
 - Added `transform` filter, which allows you to rotate, scale, translate, mesh coordinates
 - Added python script in src/utilities/visit_session_converters to convert VisIt color table to Ascent actions color table
+- Added `fields` option to the project 2d to support scalar rendering of specific fields.
 
 ### Changed
 - Changed the replay utility's binary names such that `replay_ser` is now `ascent_replay` and `raplay_mpi` is now `ascent_replay_mpi`. This will help prevent potential name collisions with other tools that also have replay utilities. 

src/libs/ascent/runtimes/flow_filters/ascent_runtime_vtkh_filters.cpp

@@ -4018,13 +4018,21 @@ VTKHProject2d::verify_params(const conduit::Node &params,
     res &= check_numeric("image_width",params, info, false);
     res &= check_numeric("image_height",params, info, false);
 
+    if(params.has_child("fields") && !params["fields"].dtype().is_list())
+    {
+      res = false;
+      info["errors"].append() = "fields is not a list";
+    }
+
     std::vector<std::string> valid_paths;
     std::vector<std::string> ignore_paths;
     valid_paths.push_back("topology");
     valid_paths.push_back("image_width");
     valid_paths.push_back("image_height");
-    valid_paths.push_back("camera");
     ignore_paths.push_back("camera");
+    valid_paths.push_back("fields");
+    ignore_paths.push_back("fields");
+    valid_paths.push_back("camera");
 
     std::string surprises = surprise_check(valid_paths, ignore_paths, params);
 
@@ -4074,11 +4082,35 @@ VTKHProject2d::execute()
     vtkm::rendering::Camera camera;
     camera.ResetToBounds(bounds);
 
+    std::vector<std::string> field_names;
+
     if(params().has_path("camera"))
     {
       parse_camera(params()["camera"], camera);
     }
 
+    if(params().has_path("fields"))
+    {
+
+      const conduit::Node &flist = params()["fields"];
+      const int num_fields = flist.number_of_children();
+
+      if(num_fields == 0)
+      {
+        ASCENT_ERROR("'fields' list must be non-empty");
+      }
+
+      for(int i = 0; i < num_fields; i++)
+      {
+        const conduit::Node &f = flist.child(i); 
+        if(!f.dtype().is_string())
+        {
+            ASCENT_ERROR("'fields' list values must be a string");
+        }
+        field_names.push_back(f.as_string());
+      }
+    }
+
     int width = 512;
     int height = 512;
     if(params().has_path("image_width"))
@@ -4096,7 +4128,7 @@ VTKHProject2d::execute()
     tracer.SetHeight(height);
     tracer.SetInput(&data);
     tracer.SetCamera(camera);
-
+    tracer.SetFields(field_names);
     tracer.Update();
 
     vtkh::DataSet *output = tracer.GetOutput();

src/tests/ascent/t_ascent_scalar_renderer.cpp

@@ -58,7 +58,7 @@ TEST(ascent_scalar_rendering, test_scalar_rendering)
 
     EXPECT_TRUE(conduit::blueprint::mesh::verify(data,verify_info));
 
-    ASCENT_INFO("Testing scalar  Rendering");
+    ASCENT_INFO("Testing Scalar Rendering");
 
 
     string output_path = prepare_output_dir();
@@ -98,7 +98,6 @@ TEST(ascent_scalar_rendering, test_scalar_rendering)
     //
 
     Ascent ascent;
-
     Node ascent_opts;
     ascent_opts["runtime/type"] = "ascent";
     ascent.open(ascent_opts);
@@ -111,6 +110,85 @@ TEST(ascent_scalar_rendering, test_scalar_rendering)
     ASCENT_ACTIONS_DUMP(actions,output_file,msg);
 }
 
+
+//-----------------------------------------------------------------------------
+TEST(ascent_scalar_rendering, test_scalar_rendering_fields_specified)
+{
+    // the vtkm runtime is currently our only rendering runtime
+    Node n;
+    ascent::about(n);
+    // only run this test if ascent was built with vtkm support
+    if(n["runtimes/ascent/vtkm/status"].as_string() == "disabled")
+    {
+        ASCENT_INFO("Ascent support disabled, skipping test");
+        return;
+    }
+
+
+    //
+    // Create an example mesh.
+    //
+    Node data, verify_info;
+    conduit::blueprint::mesh::examples::braid("hexs",
+                                              EXAMPLE_MESH_SIDE_DIM,
+                                              EXAMPLE_MESH_SIDE_DIM,
+                                              EXAMPLE_MESH_SIDE_DIM,
+                                              data);
+
+    EXPECT_TRUE(conduit::blueprint::mesh::verify(data,verify_info));
+
+    ASCENT_INFO("Testing Scalar Rendering with fields specified");
+
+
+    string output_path = prepare_output_dir();
+    string output_file = conduit::utils::join_file_path(output_path,"tout_scalar_rendering_fields_specified");
+
+    //
+    // Create the actions.
+    //
+
+    conduit::Node pipelines;
+    // pipeline 1
+    pipelines["pl1/f1/type"] = "project_2d";
+    // filter knobs
+    conduit::Node &params = pipelines["pl1/f1/params"];
+    params["image_width"] = 512;
+    params["image_height"] = 512;
+    params["fields"].append() = "braid";
+
+    conduit::Node extracts;
+    extracts["e1/type"]  = "relay";
+    extracts["e1/pipeline"] = "pl1";
+
+    extracts["e1/params/path"] = output_file;
+    extracts["e1/params/protocol"] = "blueprint/mesh/hdf5";
+
+    conduit::Node actions;
+    // add the extracts
+    conduit::Node &add_extracts = actions.append();
+    add_extracts["action"] = "add_extracts";
+    add_extracts["extracts"] = extracts;
+    // add the pipeline
+    conduit::Node &add_pipelines= actions.append();
+    add_pipelines["action"] = "add_pipelines";
+    add_pipelines["pipelines"] = pipelines;
+
+    //
+    // Run Ascent
+    //
+
+    Ascent ascent;
+    Node ascent_opts;
+    ascent.open(ascent_opts);
+    ascent.publish(data);
+    ascent.execute(actions);
+    ascent.close();
+
+    // check that we created an image
+    std::string msg = "An example of scalar rendering of specific fields";
+    ASCENT_ACTIONS_DUMP(actions,output_file,msg);
+}
+
 //-----------------------------------------------------------------------------
 int main(int argc, char* argv[])
 {