ENH: Enable selection of translucent geometry

vtkHardwareSelector was skipping all translucent geometry and selecting only
opaque geometry. This change enables selection of translucent as well as opaque
geometry. Totally transparent (opacity = 0.0) is skipped.
This change fixes ParaView issue 14412

Change-Id: Ic8ead1534b4f24695e5138fc8207250f25450508

Rendering/Core/vtkActor.cxx

@@ -127,7 +127,6 @@ int vtkActor::GetIsOpaque()
   return is_opaque? 1 : 0;
 }
 
-
 //----------------------------------------------------------------------------
 // This causes the actor to be rendered. It in turn will render the actor's
 // property, texture map and then mapper. If a property hasn't been
@@ -150,8 +149,10 @@ int vtkActor::RenderOpaqueGeometry(vtkViewport *vp)
     this->GetProperty();
     }
 
-  // is this actor opaque ?
-  if (this->GetIsOpaque())
+  // is this actor opaque
+  // Do this check only when not in selection mode
+  if (this->GetIsOpaque() ||
+    (ren->GetSelector() && this->Property->GetOpacity() > 0.0))
     {
     this->Property->Render(this, ren);
 

Rendering/LOD/vtkLODActor.cxx

@@ -201,7 +201,9 @@ int vtkLODActor::RenderOpaqueGeometry(vtkViewport *vp)
     }
 
   // is this actor opaque ?
-  if (this->GetIsOpaque())
+  // Do this check only when not in selection mode
+  if (this->GetIsOpaque() ||
+    (ren->GetSelector() && this->Property->GetOpacity() > 0.0))
     {
     this->Property->Render(this, ren);
 

Rendering/LOD/vtkQuadricLODActor.cxx

@@ -89,7 +89,9 @@ int vtkQuadricLODActor::RenderOpaqueGeometry(vtkViewport *vp)
     }
 
   // is this actor opaque ?
-  if (this->GetIsOpaque())
+  // Do this check only when not in selection mode
+  if (this->GetIsOpaque() ||
+    (ren->GetSelector() && this->Property->GetOpacity() > 0.0))
     {
     this->GetProperty()->Render(this, ren);
 

Rendering/OpenGL/Testing/Cxx/TestAreaSelections.cxx

@@ -42,6 +42,7 @@
 #include "vtkExtractSelectedFrustum.h"
 #include "vtkDataSetMapper.h"
 #include "vtkSmartPointer.h"
+#include "vtkProperty.h"
 
 #include "vtkDataSetReader.h"
 
@@ -174,6 +175,8 @@ int TestAreaSelections(int argc, char* argv[])
   MY_CREATE_NEW(vtkActor, act2);
   act2->SetMapper(map2);
   act2->PickableOn(); //lets the HardwareSelector select in it
+  act2->GetProperty()->SetColor(0.2,0.1,0.5);
+  act2->GetProperty()->SetOpacity(0.6);
   renderer->AddActor(act2);
 
   sMap = vtkSmartPointer<vtkDataSetMapper>::New();

Rendering/OpenGL/Testing/Data/Baseline/TestAreaSelections.png.md5

-5b8df0c9a12363520ebc6dc0968d3330
+1fbd324f95c99f7faad0c57810d1eb8d