File 0001-Allow-compilation-on-GLES-platforms.patch of Package vtk

From 2d5a68b91f9d638aa408285d1608bc5d70060602 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Stefan=20Br=C3=BCns?= <stefan.bruens@rwth-aachen.de>
Date: Fri, 1 Sep 2017 02:11:37 +0200
Subject: [PATCH] Allow compilation on GLES platforms
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

On GLES 2.0 platforms (more specifically, for Qt5 "opengl es2" builds),
QOpenGLFunctions_3_2_Core does not exist. Since Qt 5.7,
QOpenGlFramebufferObject has a static wrapper method for framebuffer
blitting, which in worst case is a noop.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
---
 GUISupport/Qt/QVTKOpenGLWidget.cxx | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/GUISupport/Qt/QVTKOpenGLWidget.cxx b/GUISupport/Qt/QVTKOpenGLWidget.cxx
index a1676e8..16e255f 100644
--- a/GUISupport/Qt/QVTKOpenGLWidget.cxx
+++ b/GUISupport/Qt/QVTKOpenGLWidget.cxx
@@ -421,10 +421,15 @@ void QVTKOpenGLWidget::paintGL()
 
   // blit from this->FBO to QOpenGLWidget's FBO.
   vtkQVTKOpenGLWidgetDebugMacro("paintGL::blit-to-defaultFBO");
+#if QT_VERSION < 0x050700
   QOpenGLFunctions_3_2_Core* f =
     QOpenGLContext::currentContext()->versionFunctions<QOpenGLFunctions_3_2_Core>();
+#else
+  QOpenGLFunctions* f = QOpenGLContext::currentContext()->functions();
+#endif
   if (f)
   {
+#if QT_VERSION < 0x050700
     f->glBindFramebuffer(GL_DRAW_FRAMEBUFFER, this->defaultFramebufferObject());
     f->glDrawBuffer(GL_COLOR_ATTACHMENT0);
 
@@ -434,6 +439,13 @@ void QVTKOpenGLWidget::paintGL()
     f->glBlitFramebuffer(0, 0, this->RenderWindow->GetSize()[0], this->RenderWindow->GetSize()[1],
       0, 0, this->RenderWindow->GetSize()[0], this->RenderWindow->GetSize()[1], GL_COLOR_BUFFER_BIT,
       GL_NEAREST);
+#else
+    f->glDisable(GL_SCISSOR_TEST); // Scissor affects glBindFramebuffer.
+    QRect rect(0, 0, this->RenderWindow->GetSize()[0], this->RenderWindow->GetSize()[1]);
+    QOpenGLFramebufferObject::blitFramebuffer(0 /* binds to default framebuffer */, rect,
+      this->FBO, rect, GL_COLOR_BUFFER_BIT, GL_NEAREST, GL_COLOR_ATTACHMENT0,
+      GL_COLOR_ATTACHMENT0, QOpenGLFramebufferObject::DontRestoreFramebufferBinding);
+#endif
 
     // now clear alpha otherwise we end up blending the rendering with
     // background windows in certain cases. It happens on OsX
-- 
2.14.1