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;
@@ -460,91 +458,91 @@ void Viewer::init()
   d->buffer.create();
   
   //setting the program used for the distance
-     {
-         //Vertex source code
-         const char vertex_source_dist[] =
-         {
-             "#version 150  \n"
-             "in vec4 vertex;\n"
-             "uniform mat4 mvp_matrix;\n"
-             "uniform float point_size;\n"
-             "void main(void)\n"
-             "{\n"
-             "   gl_PointSize = point_size; \n"
-             "   gl_Position = mvp_matrix * vertex; \n"
-             "} \n"
-             "\n"
-         };
-         const char vertex_source_comp_dist[] =
-         {
-             "attribute highp vec4 vertex;\n"
-             "uniform highp mat4 mvp_matrix;\n"
-             "uniform highp float point_size;\n"
-             "void main(void)\n"
-             "{\n"
-             "   gl_PointSize = point_size; \n"
-             "   gl_Position = mvp_matrix * vertex; \n"
-             "} \n"
-             "\n"
-         };
-         //Fragment source code
-         const char fragment_source_dist[] =
-         {
-             "#version 150  \n"
-             "out vec4 out_color; \n"
-             "void main(void) { \n"
-             "out_color = vec4(0.0,0.0,0.0,1.0); \n"
-             "} \n"
-             "\n"
-         };
-         const char fragment_source_comp_dist[] =
-         {
-             "void main(void) { \n"
-             "gl_FragColor = vec4(0.0,0.0,0.0,1.0); \n"
-             "} \n"
-             "\n"
-         };
-         QOpenGLShader vertex_shader(QOpenGLShader::Vertex);
-         QOpenGLShader fragment_shader(QOpenGLShader::Fragment);
-         if(isOpenGL_4_3())
-         {
-           if(!vertex_shader.compileSourceCode(vertex_source_dist))
-           {
-             std::cerr<<"Compiling vertex source FAILED"<<std::endl;
-           }
-           
-           if(!fragment_shader.compileSourceCode(fragment_source_dist))
-           {
-             std::cerr<<"Compiling fragmentsource FAILED"<<std::endl;
-           }
-         }
-         else
-         {
-           if(!vertex_shader.compileSourceCode(vertex_source_comp_dist))
-           {
-             std::cerr<<"Compiling vertex source FAILED"<<std::endl;
-           }
-           
-           if(!fragment_shader.compileSourceCode(fragment_source_comp_dist))
-           {
-             std::cerr<<"Compiling fragmentsource FAILED"<<std::endl;
-           }
-         }
-         if(!d->rendering_program_dist.addShader(&vertex_shader))
-         {
-             std::cerr<<"adding vertex shader FAILED"<<std::endl;
-         }
-         if(!d->rendering_program_dist.addShader(&fragment_shader))
-         {
-             std::cerr<<"adding fragment shader FAILED"<<std::endl;
-         }
-         if(!d->rendering_program_dist.link())
-         {
-             qDebug() << d->rendering_program_dist.log();
-         }
-     }
+  if(!is_linked)
+  {
+    //Vertex source code
+    const char vertex_source_dist[] =
+    {
+      "#version 150  \n"
+      "in vec4 vertex;\n"
+      "uniform mat4 mvp_matrix;\n"
+      "uniform float point_size;\n"
+      "void main(void)\n"
+      "{\n"
+      "   gl_PointSize = point_size; \n"
+      "   gl_Position = mvp_matrix * vertex; \n"
+      "} \n"
+      "\n"
+    };
+    const char vertex_source_comp_dist[] =
+    {
+      "attribute highp vec4 vertex;\n"
+      "uniform highp mat4 mvp_matrix;\n"
+      "uniform highp float point_size;\n"
+      "void main(void)\n"
+      "{\n"
+      "   gl_PointSize = point_size; \n"
+      "   gl_Position = mvp_matrix * vertex; \n"
+      "} \n"
+      "\n"
+    };
+    //Fragment source code
+    const char fragment_source_dist[] =
+    {
+      "#version 150  \n"
+      "out vec4 out_color; \n"
+      "void main(void) { \n"
+      "out_color = vec4(0.0,0.0,0.0,1.0); \n"
+      "} \n"
+      "\n"
+    };
+    const char fragment_source_comp_dist[] =
+    {
+      "void main(void) { \n"
+      "gl_FragColor = vec4(0.0,0.0,0.0,1.0); \n"
+      "} \n"
+      "\n"
+    };
+    QOpenGLShader vertex_shader(QOpenGLShader::Vertex);
+    QOpenGLShader fragment_shader(QOpenGLShader::Fragment);
+    if(isOpenGL_4_3())
+    {
+      if(!vertex_shader.compileSourceCode(vertex_source_dist))
+      {
+        std::cerr<<"Compiling vertex source FAILED"<<std::endl;
+      }
+
+      if(!fragment_shader.compileSourceCode(fragment_source_dist))
+      {
+        std::cerr<<"Compiling fragmentsource FAILED"<<std::endl;
+      }
+    }
+    else
+    {
+      if(!vertex_shader.compileSourceCode(vertex_source_comp_dist))
+      {
+        std::cerr<<"Compiling vertex source FAILED"<<std::endl;
+      }
+
+      if(!fragment_shader.compileSourceCode(fragment_source_comp_dist))
+      {
+        std::cerr<<"Compiling fragmentsource FAILED"<<std::endl;
+      }
+    }
+    if(!d->rendering_program_dist.addShader(&vertex_shader))
+    {
+      std::cerr<<"adding vertex shader FAILED"<<std::endl;
+    }
+    if(!d->rendering_program_dist.addShader(&fragment_shader))
+    {
+      std::cerr<<"adding fragment shader FAILED"<<std::endl;
+    }
+    if(!d->rendering_program_dist.link())
+    {
+      qDebug() << d->rendering_program_dist.log();
+    }
+  }
   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();
 }