From 1f6ef23b98ce8841d9d63146f38e7e5e1450e11d Mon Sep 17 00:00:00 2001
From: Matt Larsen <larsen30@llnl.gov>
Date: Thu, 9 Feb 2017 16:26:23 -0800
Subject: [PATCH] adding the ability to turn off background compositing for
 volume renderer

---
 vtkm/rendering/MapperVolume.cxx                  | 10 +++++++++-
 vtkm/rendering/MapperVolume.h                    |  1 +
 .../raytracing/VolumeRendererStructured.h        | 16 ++++++++++++----
 3 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/vtkm/rendering/MapperVolume.cxx b/vtkm/rendering/MapperVolume.cxx
index af336f16d..cba681df1 100644
--- a/vtkm/rendering/MapperVolume.cxx
+++ b/vtkm/rendering/MapperVolume.cxx
@@ -40,6 +40,7 @@ struct MapperVolume::InternalsType
 {
   vtkm::rendering::CanvasRayTracer *Canvas;
   vtkm::Float32 SampleDistance;
+  bool CompositeBackground;
   vtkm::cont::internal::RuntimeDeviceTracker DeviceTracker;
   std::shared_ptr<vtkm::cont::internal::SimplePolymorphicContainerBase>
       RayTracerContainer;
@@ -47,7 +48,8 @@ struct MapperVolume::InternalsType
   VTKM_CONT
   InternalsType()
     : Canvas(nullptr),
-      SampleDistance(-1.f)
+      SampleDistance(-1.f),
+      CompositeBackground(true)
   {  }
 
   template<typename Device>
@@ -149,6 +151,7 @@ struct MapperVolume::RenderFunctor
     tracer->GetCamera().SetParameters(this->Camera,
                                       *this->Self->Internals->Canvas);
     tracer->SetSampleDistance(this->Self->Internals->SampleDistance);
+    tracer->SetCompositeBackground(this->Self->Internals->CompositeBackground);
     vtkm::Bounds dataBounds = this->Coordinates.GetBounds(Device());
 
     tracer->SetData(this->Coordinates,
@@ -213,5 +216,10 @@ void MapperVolume::SetSampleDistance(const vtkm::Float32 sampleDistance)
   this->Internals->SampleDistance = sampleDistance;
 }
 
+void MapperVolume::SetCompositeBackground(const bool compositeBackground)
+{
+  this->Internals->CompositeBackground = compositeBackground;
+}
+
 }
 } // namespace vtkm::rendering
diff --git a/vtkm/rendering/MapperVolume.h b/vtkm/rendering/MapperVolume.h
index 82fbc89ee..c76e6c345 100644
--- a/vtkm/rendering/MapperVolume.h
+++ b/vtkm/rendering/MapperVolume.h
@@ -49,6 +49,7 @@ public:
 
   vtkm::rendering::Mapper *NewCopy() const VTKM_OVERRIDE;
   void SetSampleDistance(const vtkm::Float32 distance);
+  void SetCompositeBackground(const bool compositeBackground);
 private:
   struct InternalsType;
   std::shared_ptr<InternalsType> Internals;
diff --git a/vtkm/rendering/raytracing/VolumeRendererStructured.h b/vtkm/rendering/raytracing/VolumeRendererStructured.h
index 9ac686d6c..a0de1a6a0 100644
--- a/vtkm/rendering/raytracing/VolumeRendererStructured.h
+++ b/vtkm/rendering/raytracing/VolumeRendererStructured.h
@@ -943,6 +943,7 @@ class SamplerCellAssocRect : public vtkm::worklet::WorkletMapField
     IsSceneDirty = false;
     IsUniformDataSet = true;
     SampleDistance = -1.f;
+    DoCompositeBackground = false;
   }
 
   VTKM_CONT
@@ -1078,10 +1079,11 @@ class SamplerCellAssocRect : public vtkm::worklet::WorkletMapField
         }
      }
 
-
-    vtkm::worklet::DispatcherMapField< CompositeBackground >( CompositeBackground( BackgroundColor ) )
-      .Invoke( camera.FrameBuffer );
-
+    if(DoCompositeBackground)
+    {
+      vtkm::worklet::DispatcherMapField< CompositeBackground >( CompositeBackground( BackgroundColor ) )
+        .Invoke( camera.FrameBuffer );
+    }
     camera.WriteToSurface(canvas, Rays.MinDistance);
   } //Render
 
@@ -1099,9 +1101,15 @@ class SamplerCellAssocRect : public vtkm::worklet::WorkletMapField
     BackgroundColor = backgroundColor;
   }
 
+  void SetCompositeBackground(bool compositeBackground)
+  {
+    DoCompositeBackground = compositeBackground;
+  }
+  
 protected:
   bool IsSceneDirty;
   bool IsUniformDataSet;
+  bool DoCompositeBackground;
   VolumeRay<DeviceAdapter> Rays;
   Camera<DeviceAdapter> camera;
   vtkm::cont::DynamicArrayHandleCoordinateSystem Coordinates;