Ensure depth function is GL_LEQUAL in Qt widgets

Scheiermann · Nov 13, 2020 · cdab8fa · cdab8fa
1 parent 4164413
commit cdab8fa
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Showing 2 changed files with 10 additions and 7 deletions.
diff --git a/GUISupport/Qt/QVTKOpenGLNativeWidget.cxx b/GUISupport/Qt/QVTKOpenGLNativeWidget.cxx
@@ -246,6 +246,11 @@ void QVTKOpenGLNativeWidget::paintGL()
   this->Superclass::paintGL();
   if (this->RenderWindow)
   {
+    auto ostate = this->RenderWindow->GetState();
+    ostate->Reset();
+    ostate->Push();
+    // By default, Qt sets the depth function to GL_LESS but VTK expects GL_LEQUAL
+    ostate->vtkglDepthFunc(GL_LEQUAL);
     Q_ASSERT(this->RenderWindowAdapter);
     this->RenderWindowAdapter->paint();
 
@@ -255,9 +260,6 @@ void QVTKOpenGLNativeWidget::paintGL()
     // before proceeding with blit-ing.
     this->makeCurrent();
 
-    auto ostate = this->RenderWindow->GetState();
-    ostate->Reset();
-    ostate->Push();
     const QSize deviceSize = this->size() * this->devicePixelRatioF();
     this->RenderWindowAdapter->blit(
       this->defaultFramebufferObject(), GL_COLOR_ATTACHMENT0, QRect(QPoint(0, 0), deviceSize));

diff --git a/GUISupport/Qt/QVTKOpenGLWindow.cxx b/GUISupport/Qt/QVTKOpenGLWindow.cxx
@@ -238,6 +238,11 @@ void QVTKOpenGLWindow::paintGL()
   this->Superclass::paintGL();
   if (this->RenderWindow)
   {
+    auto ostate = this->RenderWindow->GetState();
+    ostate->Reset();
+    ostate->Push();
+    // By default, Qt sets the depth function to GL_LESS but VTK expects GL_LEQUAL
+    ostate->vtkglDepthFunc(GL_LEQUAL);
     Q_ASSERT(this->RenderWindowAdapter);
     this->RenderWindowAdapter->paint();
 
@@ -247,10 +252,6 @@ void QVTKOpenGLWindow::paintGL()
     // before proceeding with blit-ing.
     this->makeCurrent();
 
-    auto ostate = this->RenderWindow->GetState();
-    ostate->Reset();
-    ostate->Push();
-
     const QSize deviceSize = this->size() * this->devicePixelRatioF();
     const auto fmt = this->context()->format();
     if (fmt.stereo() && this->RenderWindow->GetStereoRender() &&