Gui: Fix render order of datum planes

src/Gui/Inventor/So3DAnnotation.cpp

@@ -35,8 +35,41 @@
 
 using namespace Gui;
 
+SO_ELEMENT_SOURCE(SoDelayedAnnotationsElement);
+
+void SoDelayedAnnotationsElement::init(SoState* state)
+{
+    SoElement::init(state);
+}
+
+void SoDelayedAnnotationsElement::initClass()
+{
+    SO_ELEMENT_INIT_CLASS(SoDelayedAnnotationsElement, inherited);
+
+    SO_ENABLE(SoGLRenderAction, SoDelayedAnnotationsElement);
+}
+
+void SoDelayedAnnotationsElement::addDelayedPath(SoState* state, SoPath* path)
+{
+    auto elt = static_cast<SoDelayedAnnotationsElement*>(state->getElementNoPush(classStackIndex));
+
+    elt->paths.append(path);
+}
+
+SoPathList SoDelayedAnnotationsElement::getDelayedPaths(SoState* state)
+{
+    auto elt = static_cast<SoDelayedAnnotationsElement*>(state->getElementNoPush(classStackIndex));
+    auto copy = elt->paths;
+
+    elt->paths.truncate(0);
+
+    return copy;
+}
+
 SO_NODE_SOURCE(So3DAnnotation);
 
+bool So3DAnnotation::render = false;
+
 So3DAnnotation::So3DAnnotation()
 {
     SO_NODE_CONSTRUCTOR(So3DAnnotation);
@@ -65,25 +98,23 @@ void So3DAnnotation::GLRender(SoGLRenderAction* action)
 
 void So3DAnnotation::GLRenderBelowPath(SoGLRenderAction* action)
 {
-    if (action->isRenderingDelayedPaths()) {
-        glClear(GL_DEPTH_BUFFER_BIT);
+    if (render) {
         inherited::GLRenderBelowPath(action);
     }
     else {
         SoCacheElement::invalidate(action->getState());
-        action->addDelayedPath(action->getCurPath()->copy());
+        SoDelayedAnnotationsElement::addDelayedPath(action->getState(), action->getCurPath()->copy());
     }
 }
 
 void So3DAnnotation::GLRenderInPath(SoGLRenderAction* action)
 {
-    if (action->isRenderingDelayedPaths()) {
-        glClear(GL_DEPTH_BUFFER_BIT);
+    if (render) {
         inherited::GLRenderInPath(action);
     }
     else {
         SoCacheElement::invalidate(action->getState());
-        action->addDelayedPath(action->getCurPath()->copy());
+        SoDelayedAnnotationsElement::addDelayedPath(action->getState(), action->getCurPath()->copy());
     }
 }
 

src/Gui/Inventor/So3DAnnotation.h

@@ -24,11 +24,48 @@
 
 #include <Inventor/actions/SoGLRenderAction.h>
 #include <Inventor/nodes/SoSeparator.h>
+#include <Inventor/elements/SoElement.h>
 #include <FCGlobal.h>
 
 namespace Gui
 {
 
+class GuiExport SoDelayedAnnotationsElement: public SoElement
+{
+    using inherited = SoElement;
+
+    SO_ELEMENT_HEADER(SoDelayedAnnotationsElement);
+
+protected:
+    ~SoDelayedAnnotationsElement() override = default;
+
+    SoDelayedAnnotationsElement& operator=(const SoDelayedAnnotationsElement& other) = default;
+    SoDelayedAnnotationsElement& operator=(SoDelayedAnnotationsElement&& other) noexcept = default;
+
+public:
+    SoDelayedAnnotationsElement(const SoDelayedAnnotationsElement& other) = delete;
+    SoDelayedAnnotationsElement(SoDelayedAnnotationsElement&& other) noexcept = delete;
+
+    void init(SoState* state) override;
+
+    static void initClass();
+
+    static void addDelayedPath(SoState* state, SoPath* path);
+    static SoPathList getDelayedPaths(SoState* state);
+
+    SbBool matches([[maybe_unused]] const SoElement* element) const override
+    {
+        return FALSE;
+    }
+
+    SoElement* copyMatchInfo() const override
+    {
+        return nullptr;
+    }
+
+    SoPathList paths;
+};
+
 /*! @brief 3D Annotation Node - Annotation with depth buffer
  *
  * This class is just like SoAnnotation with the difference that it does not disable
@@ -39,21 +76,29 @@ namespace Gui
  */
 class GuiExport So3DAnnotation: public SoSeparator
 {
-    typedef SoSeparator inherited;
+    using inherited = SoSeparator;
 
     SO_NODE_HEADER(So3DAnnotation);
 
 public:
-    static void initClass();
+    static bool render;
+
     So3DAnnotation();
 
-    virtual void GLRender(SoGLRenderAction* action);
-    virtual void GLRenderBelowPath(SoGLRenderAction* action);
-    virtual void GLRenderInPath(SoGLRenderAction* action);
-    virtual void GLRenderOffPath(SoGLRenderAction* action);
+    So3DAnnotation(const So3DAnnotation& other) = delete;
+    So3DAnnotation(So3DAnnotation&& other) noexcept = delete;
+    So3DAnnotation& operator=(const So3DAnnotation& other) = delete;
+    So3DAnnotation& operator=(So3DAnnotation&& other) noexcept = delete;
+
+    static void initClass();
+
+    void GLRender(SoGLRenderAction* action) override;
+    void GLRenderBelowPath(SoGLRenderAction* action) override;
+    void GLRenderInPath(SoGLRenderAction* action) override;
+    void GLRenderOffPath(SoGLRenderAction* action) override;
 
 protected:
-    virtual ~So3DAnnotation() = default;
+    ~So3DAnnotation() override = default;
 };
 
 }  // namespace Gui

src/Gui/SoFCDB.cpp

@@ -147,6 +147,7 @@ void Gui::SoFCDB::init()
     SoFCPathAnnotation              ::initClass();
     SoMouseWheelEvent               ::initClass();
     So3DAnnotation                  ::initClass();
+    SoDelayedAnnotationsElement     ::initClass();
 
     PropertyItem                    ::init();
     PropertySeparatorItem           ::init();

src/Gui/View3DInventorViewer.cpp

@@ -130,6 +130,8 @@
 #include "NavigationAnimation.h"
 #include "Utilities.h"
 
+#include <Inventor/So3DAnnotation.h>
+
 
 FC_LOG_LEVEL_INIT("3DViewer", true, true)
 
@@ -2387,6 +2389,11 @@ void View3DInventorViewer::renderScene()
     try {
         // Render normal scenegraph.
         inherited::actualRedraw();
+
+        So3DAnnotation::render = true;
+        glClear(GL_DEPTH_BUFFER_BIT);
+        glra->apply(SoDelayedAnnotationsElement::getDelayedPaths(state));
+        So3DAnnotation::render = false;
     }
     catch (const Base::MemoryException&) {
         // FIXME: If this exception appears then the background and camera position get broken somehow. (Werner 2006-02-01)

src/Gui/ViewProviderDatum.cpp

@@ -41,6 +41,8 @@
 #include "SoFCSelection.h"
 #include "ViewProviderCoordinateSystem.h"
 
+#include <Inventor/So3DAnnotation.h>
+
 
 using namespace Gui;
 
@@ -111,7 +113,7 @@ void ViewProviderDatum::attach(App::DocumentObject* pcObject)
     visible->addChild(pRoot);
 
     // Hidden features
-    auto hidden = new SoAnnotation();
+    auto hidden = new So3DAnnotation();
 
     // Style for hidden lines
     style = new SoDrawStyle();