Supposed to make windows able to run this demo

- Add setAttribute() to use desktop OGL in the main function
 - create a specific context in the Viewer's creator

Alpha_shapes_3/demo/Alpha_shapes_3/Alpha_shape_3.cpp

@@ -13,6 +13,7 @@ int main(int argc, char** argv)
   application.setOrganizationDomain("geometryfactory.com");
   application.setOrganizationName("GeometryFactory");
   application.setApplicationName("Alpha Shape Reconstruction");
+  application.setAttribute(Qt::AA_UseDesktopOpenGL);
 
   // Import resources from libCGALQt (Qt4 or Qt5).
   // See http://doc.trolltech.com/4.4/qdir.html#Q_INIT_RESOURCE

Alpha_shapes_3/demo/Alpha_shapes_3/CMakeLists.txt

@@ -14,7 +14,7 @@ endif()
 find_package(CGAL COMPONENTS Qt5)
 include(${CGAL_USE_FILE})
 
-find_package(Qt5 COMPONENTS Xml Script OpenGL)
+find_package(Qt5 COMPONENTS Xml Script OpenGL Svg)
 
 find_package(OpenGL)
 find_package(QGLViewer)
@@ -37,7 +37,7 @@ if ( CGAL_FOUND AND CGAL_Qt5_FOUND AND Qt5_FOUND AND OPENGL_FOUND AND QGLVIEWER_
   #qt4_automoc( MainWindow.cpp Viewer.cpp)
 
   add_executable  ( Alpha_shape_3 Alpha_shape_3.cpp MainWindow.cpp Viewer.cpp ${uis}  ${RESOURCE_FILES} )
-  qt5_use_modules(Alpha_shape_3 Xml Script OpenGL)
+  qt5_use_modules(Alpha_shape_3 Xml Script OpenGL Svg)
   add_to_cached_list( CGAL_EXECUTABLE_TARGETS Alpha_shape_3 )
 
   target_link_libraries( Alpha_shape_3 ${CGAL_LIBRARIES} ${CGAL_3RD_PARTY_LIBRARIES})

Alpha_shapes_3/demo/Alpha_shapes_3/Viewer.h

@@ -19,7 +19,7 @@ class Viewer : public QGLViewer, protected QOpenGLFunctions_3_3_Core{
   int nr_of_facets;
 public:
   Viewer(QWidget* parent)
-    : QGLViewer(parent)
+    : QGLViewer(createContext(),parent)
   {
     are_buffers_initialized = false;
   }
@@ -42,6 +42,16 @@ public:
   void draw();
 
 private:
+
+  static QGLContext* createContext()
+  {
+      QOpenGLContext *context = new QOpenGLContext();
+      QSurfaceFormat format;
+      format.setVersion(3,3);
+      format.setProfile(QSurfaceFormat::CompatibilityProfile);
+      context->setFormat(format);
+      return QGLContext::fromOpenGLContext(context);
+  }
   bool are_buffers_initialized;
   //Shaders elements
     int poly_vertexLocation;