Add a test for vtkRenderer::UseOIT

Rendering/Core/Testing/Cxx/CMakeLists.txt

@@ -95,6 +95,7 @@ vtk_add_test_cxx(vtkRenderingCoreCxxTests tests
   TestOffAxisStereo.cxx
   TestOnAndOffScreenConeCxx.cxx
   TestOpacity.cxx
+  TestOpacityMSAA.cxx
   TestOrderedTriangulator.cxx
   TestOSConeCxx.cxx
   TestPickingManager.cxx,NO_VALID

Rendering/Core/Testing/Cxx/TestOpacityMSAA.cxx

+// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
+// SPDX-License-Identifier: BSD-3-Clause
+
+/**Description
+ *
+ */
+
+#include "vtkActor.h"
+#include "vtkCamera.h"
+#include "vtkConeSource.h"
+#include "vtkNew.h"
+#include "vtkPolyDataMapper.h"
+#include "vtkProperty.h"
+#include "vtkRegressionTestImage.h"
+#include "vtkRenderWindow.h"
+#include "vtkRenderWindowInteractor.h"
+#include "vtkRenderer.h"
+#include "vtkTesting.h"
+
+int TestOpacityMSAA(int argc, char* argv[])
+{
+  cout << "CTEST_FULL_OUTPUT (Avoid ctest truncation of output)" << endl;
+
+  vtkNew<vtkConeSource> c1;
+  c1->SetResolution(1);
+  c1->SetCenter(-0.5, 0, 0);
+  c1->SetRadius(1.3);
+  vtkNew<vtkPolyDataMapper> m1;
+  m1->SetInputConnection(c1->GetOutputPort());
+  vtkNew<vtkActor> a1;
+  a1->SetMapper(m1);
+
+  vtkNew<vtkConeSource> c2;
+  c2->SetResolution(1);
+  c2->SetCenter(0.5, 0, 0);
+  c2->SetRadius(1.3);
+  c2->SetDirection(-1, 0, 0);
+  vtkNew<vtkPolyDataMapper> m2;
+  m2->SetInputConnection(c2->GetOutputPort());
+  vtkNew<vtkActor> a2;
+  a2->SetMapper(m2);
+  a2->GetProperty()->SetOpacity(0.5);
+
+  vtkNew<vtkRenderWindow> renWin;
+  renWin->SetMultiSamples(8); // enable multisampling
+  renWin->SetSize(301, 300);  // Intentional NPOT size
+
+  vtkNew<vtkRenderer> ren;
+  ren->AddActor(a1);
+  ren->AddActor(a2);
+  renWin->AddRenderer(ren);
+  ren->ResetCamera();
+  ren->GetActiveCamera()->Roll(4);
+  ren->SetUseOIT(false); // disable OIT pass
+
+  vtkNew<vtkRenderWindowInteractor> iren;
+  iren->SetRenderWindow(renWin);
+
+  renWin->Render();
+  int retVal = vtkRegressionTestImage(renWin);
+  if (retVal == vtkRegressionTester::DO_INTERACTOR)
+  {
+    iren->Start();
+  }
+
+  return !retVal;
+}

Rendering/Core/Testing/Data/Baseline/TestOpacityMSAA.png.sha512

+b5dce5a56db0d685c638e3383536bcbb1cbf0b71040989c7fad040f221f4527f761d7cd22c7e4dd63aaf368cc236e366d37c4832b07f59f50b6928d223f7da9e