Gui: add support of selection context

The patch implements context-aware selection and rendering in 3D view.

Please check [here](https://git.io/fjiY5) for more details, including
the following 'Render Caching' section.

The patch also includes modification of View3DInventorViewer to support
always-on-top selection rendering using the secondary selection context
and the new coin node SoFCPathAnnotation.

Another small change in SoQtQuarterAdaptor for more responsive frame
rate display. The original implementation reports skewed frame rate
in the presence of long idle period.

src/Gui/CMakeLists.txt

@@ -1022,6 +1022,7 @@ SET(Inventor_CPP_SRCS
     SoFCOffscreenRenderer.cpp
     SoFCSelection.cpp
     SoFCUnifiedSelection.cpp
+    SoFCSelectionContext.cpp
     SoFCSelectionAction.cpp
     SoFCVectorizeSVGAction.cpp
     SoFCVectorizeU3DAction.cpp
@@ -1047,6 +1048,7 @@ SET(Inventor_SRCS
     SoFCOffscreenRenderer.h
     SoFCSelection.h
     SoFCUnifiedSelection.h
+    SoFCSelectionContext.h
     SoFCSelectionAction.h
     SoFCVectorizeSVGAction.h
     SoFCVectorizeU3DAction.h

src/Gui/DlgSettings3DView.ui

@@ -145,6 +145,39 @@ will be shown at the lower left in opened files</string>
         </property>
        </widget>
       </item>
+      <item>
+       <layout class="QHBoxLayout">
+        <item>
+         <widget class="QLabel" name="renderCacheLabel">
+          <property name="text">
+           <string>Render cache</string>
+          </property>
+         </widget>
+        </item>
+        <item>
+         <widget class="QComboBox" name="renderCache">
+          <property name="currentIndex">
+           <number>0</number>
+          </property>
+          <item>
+           <property name="text">
+            <string>Auto</string>
+           </property>
+          </item>
+          <item>
+           <property name="text">
+            <string>Distributed</string>
+           </property>
+          </item>
+          <item>
+           <property name="text">
+            <string>Centralized</string>
+           </property>
+          </item>
+         </widget>
+        </item>
+       </layout>
+      </item>
       <item>
        <widget class="Gui::PrefCheckBox" name="CheckBox_UseAutoRotation">
         <property name="enabled">

src/Gui/DlgSettings3DViewImp.cpp

@@ -88,6 +88,9 @@ void DlgSettings3DViewImp::saveSettings()
     index = this->naviCubeCorner->currentIndex();
     hGrp->SetInt("CornerNaviCube", index);
 
+    index = this->renderCache->currentIndex();
+    hGrp->SetInt("RenderCache", index);
+
     QVariant const &vBoxMarkerSize = this->boxMarkerSize->itemData(this->boxMarkerSize->currentIndex());
     hGrp->SetInt("MarkerSize", vBoxMarkerSize.toInt());
 
@@ -158,6 +161,9 @@ void DlgSettings3DViewImp::loadSettings()
     index = hGrp->GetInt("CornerNaviCube", 1);
     naviCubeCorner->setCurrentIndex(index);
 
+    index = hGrp->GetInt("RenderCache", 0);
+    renderCache->setCurrentIndex(index);
+
     int const current = hGrp->GetInt("MarkerSize", 9L);
     this->boxMarkerSize->addItem(tr("5px"), QVariant(5));
     this->boxMarkerSize->addItem(tr("7px"), QVariant(7));

src/Gui/Quarter/SoQTQuarterAdaptor.cpp

@@ -714,32 +714,37 @@ bool SIM::Coin3D::Quarter::SoQTQuarterAdaptor::processSoEvent(const SoEvent* eve
 */
 void SIM::Coin3D::Quarter::SoQTQuarterAdaptor::paintEvent(QPaintEvent* event)
 {
+    double start = SbTime::getTimeOfDay().getValue();
     QuarterWidget::paintEvent(event);
-
-    this->framesPerSecond = addFrametime(SbTime::getTimeOfDay().getValue());
+    this->framesPerSecond = addFrametime(start);
 }
 
 void SIM::Coin3D::Quarter::SoQTQuarterAdaptor::resetFrameCounter(void)
 {
     this->framecount = 0;
-    this->frames.assign(100, 0.0f);
-    this->totaldraw = 0.0f;
+    this->frametime = 0.0f;
+    this->drawtime = 0.0f;
     this->starttime = SbTime::getTimeOfDay().getValue();
     this->framesPerSecond = SbVec2f(0, 0);
 }
 
-SbVec2f SIM::Coin3D::Quarter::SoQTQuarterAdaptor::addFrametime(double timeofday)
+SbVec2f SIM::Coin3D::Quarter::SoQTQuarterAdaptor::addFrametime(double starttime)
 {
-    int framearray_size = 100;
     this->framecount++;
 
-    int arrayptr = (this->framecount - 1) % framearray_size;
+    double timeofday = SbTime::getTimeOfDay().getValue();
+
+    // draw time is the actual time spent on rendering
+    double drawtime = timeofday - starttime;
+#define FPS_FACTOR 0.7
+    this->drawtime = (drawtime*FPS_FACTOR) + this->drawtime*(1.0-FPS_FACTOR);
 
-    double renderTime = timeofday - this->starttime;
-    this->totaldraw += (float(renderTime) - this->frames[arrayptr]);
-    float drawfps = this->totaldraw / std::min<int>(this->framecount, framearray_size);
+    // frame time is the time spent since the last frame. There could an
+    // indefinite pause between the last frame because the scene is not
+    // changing. So we limit the skew to 5 second.
+    double frametime = std::min(timeofday-this->starttime, std::max(drawtime,5000.0));
+    this->frametime = (frametime*FPS_FACTOR) + this->frametime*(1.0-FPS_FACTOR);
 
-    this->frames[arrayptr] = static_cast<float>(renderTime);
     this->starttime = timeofday;
-    return SbVec2f(1000 * drawfps, 1.0f / drawfps);
+    return SbVec2f(1000 * this->drawtime, 1.0f / this->frametime);
 }

src/Gui/Quarter/SoQTQuarterAdaptor.h

@@ -117,9 +117,8 @@ class QUARTER_DLL_API SoQTQuarterAdaptor :  public QuarterWidget {
     SoCallbackList m_interactionStartCallback;
     SoCallbackList m_interactionEndCallback;
 
-    // Keep track of the frames-per-second counter.
-    std::vector<float> frames;
-    float totaldraw;
+    double frametime;
+    double drawtime;
     double starttime;
     int framecount;
 

src/Gui/SceneInspector.cpp

@@ -25,6 +25,7 @@
 #ifndef _PreComp_
 # include <Inventor/nodes/SoSeparator.h>
 # include <QHeaderView>
+# include <QTextStream>
 #endif
 
 #include "SceneInspector.h"
@@ -102,12 +103,21 @@ void SceneModel::setNode(QModelIndex index, SoNode* node)
             setNode(this->index(i, 0, index), child);
 
             QHash<SoNode*, QString>::iterator it = nodeNames.find(child);
-            if (it != nodeNames.end()) {
-                this->setData(this->index(i, 1, index), QVariant(it.value()));
-            }
-            else {
-                this->setData(this->index(i, 1, index), QVariant(QString::fromLatin1(child->getName())));
+            QString name;
+            QTextStream stream(&name);
+            stream << child << ", ";
+            if(child->isOfType(SoSwitch::getClassTypeId())) {
+                auto pcSwitch = static_cast<SoSwitch*>(child);
+                stream << pcSwitch->whichChild.getValue() << ", ";
+            } else if (child->isOfType(SoSeparator::getClassTypeId())) {
+                auto pcSeparator = static_cast<SoSeparator*>(child);
+                stream << pcSeparator->renderCaching.getValue() << ", ";
             }
+            if (it != nodeNames.end())
+                stream << it.value();
+            else
+                stream << child->getName();
+            this->setData(this->index(i, 1, index), QVariant(name));
         }
     }
     // insert icon

src/Gui/SoFCDB.cpp

@@ -122,6 +122,9 @@ void Gui::SoFCDB::init()
     MarkerBitmaps                   ::initClass();
     SoFCCSysDragger                 ::initClass();
     SmSwitchboard                   ::initClass();
+    SoFCSeparator                   ::initClass();
+    SoFCSelectionRoot               ::initClass();
+    SoFCPathAnnotation              ::initClass();
 
     PropertyItem                    ::init();
     PropertySeparatorItem           ::init();
@@ -203,6 +206,9 @@ void Gui::SoFCDB::finish()
     SoFCSelectionColorAction        ::finish();
     SoUpdateVBOAction               ::finish();
     SoFCHighlightColorAction        ::finish();
+    SoFCSeparator                   ::finish();
+    SoFCSelectionRoot               ::finish();
+    SoFCPathAnnotation              ::finish();
 
     storage->unref();
     storage = nullptr;

src/Gui/SoFCInteractiveElement.cpp

@@ -23,6 +23,7 @@
 
 #include "PreCompiled.h"
 
+#include <Inventor/elements/SoOverrideElement.h>
 #include "SoFCInteractiveElement.h"
 
 using namespace Gui;
@@ -248,6 +249,16 @@ void SoGLVBOActivatedElement::get(SoState * state, SbBool& active)
     const SoGLVBOActivatedElement* self =  static_cast<const SoGLVBOActivatedElement *>
         (SoElement::getConstElement(state, classStackIndex));
     active = self->active;
+    if(active) {
+        uint32_t flags = SoOverrideElement::getFlags(state);
+        if(flags & (SoOverrideElement::COLOR_INDEX|
+                    SoOverrideElement::DIFFUSE_COLOR|
+                    SoOverrideElement::MATERIAL_BINDING|
+                    SoOverrideElement::TRANSPARENCY|
+                    SoOverrideElement::NORMAL_VECTOR|
+                    SoOverrideElement::NORMAL_BINDING))
+            active = false;
+    }
 }
 
 void SoGLVBOActivatedElement::push(SoState * state)