From 9dbf92a7ba561692a7304101d4ab2ea2e7a7e04f Mon Sep 17 00:00:00 2001
From: Viktor UZLOV <vuzlov@salomex.nnov.opencascade.com>
Date: Wed, 5 May 2021 17:00:10 +0300
Subject: [PATCH] Prevent VTK view becoming transparent when rendering
 transparent objects, when using MESA

---
 src/SVTK/SVTK_ViewWindow.cxx | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/SVTK/SVTK_ViewWindow.cxx b/src/SVTK/SVTK_ViewWindow.cxx
index 67fccd088..bc5c84550 100644
--- a/src/SVTK/SVTK_ViewWindow.cxx
+++ b/src/SVTK/SVTK_ViewWindow.cxx
@@ -112,6 +112,9 @@
 #include <GL/gl.h>
 #endif
 
+// Use workaround for rendering transparent object over MESA
+#defing USE_WORKAROUND_FOR_MESA
+
 namespace SVTK
 {
   int convertAction( const int accelAction )
@@ -251,6 +254,11 @@ void SVTK_ViewWindow::Initialize(SVTK_ViewModelBase* theModel)
   myKeyFreeInteractorStyle->AddObserver(SVTK::OperationFinished,
                                         myEventCallbackCommand.GetPointer(), 0.0);
 
+#ifdef USE_WORKAROUND_FOR_MESA
+  char *mesavar = getenv("SALOME_USE_MESA");
+  if (mesavar)
+    getRenderer()->SetUseDepthPeeling(1);
+#endif //USE_WORKAROUND_FOR_MESA
 
   getRenderer()->SetBackgroundAlpha(1.0);
   myInteractor->getRenderWindow()->SetMultiSamples(0);
-- 
2.39.2