From e780f55ddd43b8139429b5230d08951371cf803a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20Sch=C3=B6berl?= <joachim.schoeberl@tuwien.ac.at>
Date: Tue, 1 Nov 2016 21:04:31 +0100
Subject: [PATCH 1/2] include glew

---
 libsrc/visualization/vssolution.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/libsrc/visualization/vssolution.cpp b/libsrc/visualization/vssolution.cpp
index bc73ad27..36484d3b 100644
--- a/libsrc/visualization/vssolution.cpp
+++ b/libsrc/visualization/vssolution.cpp
@@ -8,7 +8,9 @@
 
 // #include <parallel.hpp>
 #include <visual.hpp>
-
+#ifdef WIN32
+#include <GL/glew.hpp>
+#endif
 #include <limits>
 namespace netgen
 {

From 08a662ae7731eefd40224807a2e7d3eea7a0914a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Joachim=20Sch=C3=B6berl?= <joachim.schoeberl@tuwien.ac.at>
Date: Wed, 2 Nov 2016 06:05:08 +0100
Subject: [PATCH 2/2] optional use of opengl-buffers (not supported on WIN
 without additional library)

---
 libsrc/visualization/vssolution.cpp | 27 +++++++++++++++++++--------
 libsrc/visualization/vssolution.hpp |  3 +++
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/libsrc/visualization/vssolution.cpp b/libsrc/visualization/vssolution.cpp
index 36484d3b..6a02e54e 100644
--- a/libsrc/visualization/vssolution.cpp
+++ b/libsrc/visualization/vssolution.cpp
@@ -8,9 +8,6 @@
 
 // #include <parallel.hpp>
 #include <visual.hpp>
-#ifdef WIN32
-#include <GL/glew.hpp>
-#endif
 #include <limits>
 namespace netgen
 {
@@ -441,10 +438,20 @@ namespace netgen
 	// glEnable(GL_BLEND); 
 	glDisable(GL_BLEND); 
 	glCallList (surfellist);
+        
+#ifdef USE_BUFFERS
         static int timer = NgProfiler::CreateTimer ("Solution::drawing - DrawSurfaceElements VBO");
         NgProfiler::StartTimer(timer);
+        glEnableClientState(GL_VERTEX_ARRAY);
+        glEnableClientState(GL_NORMAL_ARRAY);
+        glEnableClientState(GL_TEXTURE_COORD_ARRAY);
         glDrawElements(GL_TRIANGLES, surfel_vbo_size, GL_UNSIGNED_INT, 0);
+        glDisableClientState(GL_VERTEX_ARRAY);
+        glDisableClientState(GL_NORMAL_ARRAY);
+        glDisableClientState(GL_TEXTURE_COORD_ARRAY);
         NgProfiler::StopTimer(timer);
+#endif
+        
 	glDisable(GL_BLEND); 
 	/*
 	// transparent test ...
@@ -1289,26 +1296,28 @@ namespace netgen
     if (sol && sol->draw_surface) mvalues.SetSize (npt * sol->components);
       
     Array<complex<double> > valuesc(npt);
-
+    
+#ifdef USE_BUFFERS
     if (has_surfel_vbo)
       glDeleteBuffers (4, &surfel_vbo[0]);
     glGenBuffers (4, &surfel_vbo[0]);
+
     has_surfel_vbo = true;
     glBindBuffer (GL_ARRAY_BUFFER, surfel_vbo[0]);
     glBufferData (GL_ARRAY_BUFFER,
                   nse*npt*sizeof(Point<3,double>),
                   NULL, GL_STATIC_DRAW);
     glVertexPointer(3, GL_DOUBLE, 0, 0); 
-    glEnableClientState(GL_VERTEX_ARRAY);
+    // glEnableClientState(GL_VERTEX_ARRAY);
     
     glBindBuffer (GL_ARRAY_BUFFER, surfel_vbo[1]);
     glBufferData (GL_ARRAY_BUFFER,
                   nse*npt*sizeof(Vec<3,double>),
                   NULL, GL_STATIC_DRAW);
-    glEnableClientState(GL_NORMAL_ARRAY);
+    // glEnableClientState(GL_NORMAL_ARRAY);
     glNormalPointer(GL_DOUBLE, 0, 0);  
 
-    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
+    // glEnableClientState(GL_TEXTURE_COORD_ARRAY);
     glBindBuffer (GL_ARRAY_BUFFER, surfel_vbo[2]);
     glBufferData (GL_ARRAY_BUFFER, nse*npt*sizeof(double), NULL, GL_STATIC_DRAW);
     glTexCoordPointer(1, GL_DOUBLE, 0, 0);
@@ -1316,6 +1325,7 @@ namespace netgen
     glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, surfel_vbo[3]);
     glBufferData(GL_ELEMENT_ARRAY_BUFFER, nse*npt*6*sizeof(int), NULL, GL_STATIC_DRAW);
     surfel_vbo_size = 0;
+#endif
     
     
     NgProfiler::StopTimer(timerstart);
@@ -1679,6 +1689,7 @@ namespace netgen
 
             NgProfiler::StartTimer(timer2);
 
+#ifdef USE_BUFFERS
             if (drawelem && usetexture == 1 && !logscale)
               {
                 glBindBuffer (GL_ARRAY_BUFFER, surfel_vbo[0]);            
@@ -1702,7 +1713,7 @@ namespace netgen
               }
               
             else
-              
+#endif
               for (int iy = 0, ii = 0; iy < n; iy++)
                 {
                   glBegin (GL_TRIANGLE_STRIP);
diff --git a/libsrc/visualization/vssolution.hpp b/libsrc/visualization/vssolution.hpp
index 4dee9fe4..d8193d56 100644
--- a/libsrc/visualization/vssolution.hpp
+++ b/libsrc/visualization/vssolution.hpp
@@ -43,9 +43,12 @@ class DLL_HEADER VisualSceneSolution : public VisualScene
     Point<3> p;
   };
 
+  // #define USE_BUFFERS
+#ifdef USE_BUFFERS
   bool has_surfel_vbo = false;
   GLuint surfel_vbo[4]; //
   size_t surfel_vbo_size;
+#endif
   int surfellist;
   int linelist;
   int element1dlist;