workaround for multiple linking under windows.

GraphicsView/include/CGAL/Qt/qglviewer.h

@@ -1217,6 +1217,7 @@ protected:
   //C o n t e x t
   bool is_ogl_4_3;
   bool is_sharing;
+  bool is_linked;
   QOpenGLContext* shared_context;
 public:
   //! Is used to know if the openGL context is 4.3 or ES 2.0.

GraphicsView/include/CGAL/Qt/qglviewer_impl.h

@@ -160,6 +160,7 @@ void CGAL::QGLViewer::defaultConstructor() {
   _offset = CGAL::qglviewer::Vec(0,0,0);
   stored_fbo = NULL;
   is_sharing = false;
+  is_linked = false;
   shared_context = nullptr;
 }
 
@@ -275,7 +276,7 @@ void CGAL::QGLViewer::initializeGL() {
   {
     vbos[i].create();
   }
-  //program without light
+  if(!is_linked)
   {
     //Vertex source code
     const char v_s[] =
@@ -361,9 +362,6 @@ void CGAL::QGLViewer::initializeGL() {
     {
       qDebug() << rendering_program.log();
     }
-  }
-  //program with light
-  {
     //Vertex source code
     const char vertex_source[] =
     {
@@ -476,8 +474,6 @@ void CGAL::QGLViewer::initializeGL() {
     //It is said in the doc that a QOpenGLShader is 
     // only destroyed with the QOpenGLShaderProgram 
     //it has been linked with.
-    QOpenGLShader vertex_shader(QOpenGLShader::Vertex);
-    QOpenGLShader fragment_shader(QOpenGLShader::Fragment);
     if(is_ogl_4_3)
     {
       if(!vertex_shader.compileSourceCode(vertex_source))
@@ -516,7 +512,7 @@ void CGAL::QGLViewer::initializeGL() {
       qDebug() << rendering_program_light.log();
     }
   }
-
+  is_linked = true;
   // Give time to glInit to finish and then call setFullScreen().
   if (isFullScreen())
     QTimer::singleShot(100, this, SLOT(delayedFullScreen()));

Polyhedron/demo/Polyhedron/Viewer.cpp

@@ -82,7 +82,6 @@ public:
   //! Decides if the distance between APoint and BPoint must be drawn;
   bool distance_is_displayed;
   bool i_is_pressed;
-  bool initialized;
   bool z_is_pressed;
   QImage static_image;
   //!Draws the distance between two selected points.
@@ -249,7 +248,6 @@ void Viewer::doBindings()
   d->spec_power = viewer_settings.value("spec_power", 51.8).toFloat();
   d->scene = 0;
   d->projection_is_ortho = false;
-  d->initialized = false;
   d->twosides = false;
   this->setProperty("draw_two_sides", false);
   d->macro_mode = false;
@@ -460,6 +458,7 @@ void Viewer::init()
   d->buffer.create();
   
   //setting the program used for the distance
+  if(!is_linked)
   {
     //Vertex source code
     const char vertex_source_dist[] =
@@ -544,7 +543,6 @@ void Viewer::init()
     }
   }
   d->painter = new QPainter();
-  d->initialized = true;
 }
 
 #include <QMouseEvent>
@@ -1332,8 +1330,6 @@ QPainter* Viewer::getPainter(){return d->painter;}
 
 void Viewer::paintEvent(QPaintEvent *)
 {
-  if(!d->initialized)
-    initializeGL();
   paintGL();
 }