Accelerate 3D rendering with VBO support

*First step to move Part rendering using VBO instead of direct rendering
*Update comments inside the code
*Assume VBO is available if OpenGL > 3.0 is detected
*Add initial Color support to VBO rendering !
*Initial full feature VBO rendering implementation
*Modify some include issue for linux build
*Try to fix linux include header
*Reupdate header include for linux support
*Fix compilation on linux
*Fix linux and MacoOS build
*Fix glGetString definition
*Fix Windows build
*Add VBO support as an option into the Preference menu
*Fix crash while running FreeCAD test bench with new VBO rendering infrastructure (in both cases)
*Improve performances
*Compute material index only when a VBO update is required (improve frame rate by 10%)
*Clean the code
*Fix Travis compilation warning
*Try to fix Windows compilation issue
*Update include for Windows

src/Gui/DlgSettings3DView.ui

@@ -49,6 +49,19 @@
         </property>
        </widget>
       </item>
+      <item>
+       <widget class="Gui::PrefCheckBox" name="CheckBox_useVBO">
+        <property name="text">
+         <string>Use OpenGL Vertex Buffer Object (experimental)</string>
+        </property>
+        <property name="prefEntry" stdset="0">
+         <cstring>useVBO</cstring>
+        </property>
+        <property name="prefPath" stdset="0">
+         <cstring>View</cstring>
+        </property>
+       </widget>
+      </item>
       <item>
        <widget class="Gui::PrefCheckBox" name="CheckBox_UseAutoRotation">
         <property name="enabled">
@@ -515,6 +528,7 @@
  <tabstops>
   <tabstop>CheckBox_CornerCoordSystem</tabstop>
   <tabstop>CheckBox_ShowFPS</tabstop>
+  <tabstop>CheckBox_useVBO</tabstop>
   <tabstop>CheckBox_UseAutoRotation</tabstop>
   <tabstop>comboNavigationStyle</tabstop>
   <tabstop>mouseButton</tabstop>

src/Gui/DlgSettings3DViewImp.cpp

@@ -85,6 +85,7 @@ void DlgSettings3DViewImp::saveSettings()
     spinBoxZoomStep->onSave();
     CheckBox_CornerCoordSystem->onSave();
     CheckBox_ShowFPS->onSave();
+    CheckBox_useVBO->onSave();
     CheckBox_UseAutoRotation->onSave();
     FloatSpinBox_EyeDistance->onSave();
     checkBoxBacklight->onSave();
@@ -101,6 +102,7 @@ void DlgSettings3DViewImp::loadSettings()
     spinBoxZoomStep->onRestore();
     CheckBox_CornerCoordSystem->onRestore();
     CheckBox_ShowFPS->onRestore();
+    CheckBox_useVBO->onRestore();
     CheckBox_UseAutoRotation->onRestore();
     FloatSpinBox_EyeDistance->onRestore();
     checkBoxBacklight->onRestore();

src/Gui/SplitView3DInventor.cpp

@@ -89,6 +89,7 @@ void AbstractSplitView::setupSettings()
     OnChange(*hGrp,"UseBackgroundColorMid");
     OnChange(*hGrp,"UseAntialiasing");
     OnChange(*hGrp,"ShowFPS");
+    OnChange(*hGrp,"useVBO");
     OnChange(*hGrp,"Orthographic");
     OnChange(*hGrp,"HeadlightColor");
     OnChange(*hGrp,"HeadlightDirection");
@@ -226,7 +227,13 @@ void AbstractSplitView::OnChange(ParameterGrp::SubjectType &rCaller,ParameterGrp
     else if (strcmp(Reason,"ShowFPS") == 0) {
         for (std::vector<View3DInventorViewer*>::iterator it = _viewer.begin(); it != _viewer.end(); ++it)
             (*it)->setEnabledFPSCounter(rGrp.GetBool("ShowFPS",false));
+  	puts("updating FPS 1");
     }
+    else if (strcmp(Reason,"useVBO") == 0) {
+        for (std::vector<View3DInventorViewer*>::iterator it = _viewer.begin(); it != _viewer.end(); ++it)
+            (*it)->setEnableduseVBO(rGrp.GetBool("useVBO",false));
+    }
+
     else if (strcmp(Reason,"Orthographic") == 0) {
         // check whether a perspective or orthogrphic camera should be set
         if (rGrp.GetBool("Orthographic", true)) {

src/Gui/View3DInventor.cpp

@@ -177,6 +177,7 @@ View3DInventor::View3DInventor(Gui::Document* pcDocument, QWidget* parent,
     OnChange(*hGrp,"BackgroundColor4");
     OnChange(*hGrp,"UseBackgroundColorMid");
     OnChange(*hGrp,"ShowFPS");
+    OnChange(*hGrp,"useVBO");
     OnChange(*hGrp,"Orthographic");
     OnChange(*hGrp,"HeadlightColor");
     OnChange(*hGrp,"HeadlightDirection");
@@ -368,6 +369,9 @@ void View3DInventor::OnChange(ParameterGrp::SubjectType &rCaller,ParameterGrp::M
     else if (strcmp(Reason,"ShowFPS") == 0) {
         _viewer->setEnabledFPSCounter(rGrp.GetBool("ShowFPS",false));
     }
+    else if (strcmp(Reason,"useVBO") == 0) {
+	_viewer->setEnableduseVBO(rGrp.GetBool("useVBO",false));
+    }
     else if (strcmp(Reason,"Orthographic") == 0) {
         // check whether a perspective or orthogrphic camera should be set
         if (rGrp.GetBool("Orthographic", true))

src/Gui/View3DInventorViewer.cpp

@@ -787,6 +787,11 @@ void View3DInventorViewer::setEnabledFPSCounter(bool on)
     fpsEnabled = on;
 }
 
+void View3DInventorViewer::setEnableduseVBO(bool on)
+{
+    vboEnabled = on;
+}
+
 void View3DInventorViewer::setAxisCross(bool on)
 {
     SoNode* scene = getSceneGraph();
@@ -1339,7 +1344,10 @@ void View3DInventorViewer::actualRedraw()
         break;
     }
 }
-
+bool View3DInventorViewer::get_vbo_state()
+{
+	return vboEnabled;
+}
 void View3DInventorViewer::renderFramebuffer()
 {
     const SbViewportRegion vp = this->getSoRenderManager()->getViewportRegion();
@@ -1408,7 +1416,7 @@ void View3DInventorViewer::renderGLImage()
     glEnable(GL_DEPTH_TEST);
 }
 
-//#define ENABLE_GL_DEPTH_RANGE
+// #define ENABLE_GL_DEPTH_RANGE
 // The calls of glDepthRange inside renderScene() causes problems with transparent objects
 // so that's why it is disabled now: http://forum.freecadweb.org/viewtopic.php?f=3&t=6037&hilit=transparency
 
@@ -1442,6 +1450,7 @@ void View3DInventorViewer::renderScene(void)
     SoGLRenderActionElement::set(glra->getState(), glra);
     glra->apply(this->backgroundroot);
 
+
     navigation->updateAnimation();
 
     try {

src/Gui/View3DInventorViewer.h

@@ -96,6 +96,7 @@ public:
         DisallowRotation=8,/**< switch of the rotation. */
         DisallowPanning=16,/**< switch of the panning. */
         DisallowZooming=32,/**< switch of the zooming. */
+	useVBO=64,/**< switch of the OpenGL VBO usage. */
     };
     //@}
     
@@ -339,6 +340,7 @@ public:
     bool hasAxisCross(void);
     
     void setEnabledFPSCounter(bool b);
+    void setEnableduseVBO(bool b);
 
     NavigationStyle* navigationStyle() const;
 
@@ -346,6 +348,8 @@ public:
     Gui::Document* getDocument();
 
     virtual PyObject *getPyObject(void);
+    bool vboEnabled;
+    bool get_vbo_state(); 
 
 protected:
     void renderScene();