0033607: Visualization - Implementation of hardware occlusion queries

src/AIS/AIS_InteractiveContext.cxx

@@ -413,7 +413,8 @@ void AIS_InteractiveContext::Display(const Handle(AIS_InteractiveObject)& theIOb
   if (!myObjects.IsBound(theIObj))
   {
     setObjectStatus(theIObj, PrsMgr_DisplayStatus_Displayed, theDispMode, theSelectionMode);
-    theIObj->ViewAffinity()->SetVisible(true); // reset view affinity mask
+    theIObj->ViewAffinity()->SetVisible(true);      // reset view affinity mask
+    theIObj->ViewOcclusionMask()->SetVisible(true); // reset view occlusion mask
     myMainVwr->StructureManager()->RegisterObject(theIObj, theIObj->ViewAffinity());
     myMainPM->Display(theIObj, theDispMode);
     if (theSelectionMode != -1)
@@ -491,7 +492,8 @@ void AIS_InteractiveContext::Load(const Handle(AIS_InteractiveObject)& theIObj,
                     PrsMgr_DisplayStatus_Erased,
                     aDispMode,
                     theSelMode != -1 ? theSelMode : aSelModeDef);
-    theIObj->ViewAffinity()->SetVisible(true); // reset view affinity mask
+    theIObj->ViewAffinity()->SetVisible(true);      // reset view affinity mask
+    theIObj->ViewOcclusionMask()->SetVisible(true); // reset view occlusion mask
     myMainVwr->StructureManager()->RegisterObject(theIObj, theIObj->ViewAffinity());
   }
 

src/Graphic3d/FILES

@@ -208,3 +208,4 @@ Graphic3d_Layer.cxx
 Graphic3d_Layer.hxx
 Graphic3d_ZLayerId.hxx
 Graphic3d_ZLayerSettings.hxx
+Graphic3d_ViewOcclusionMask.hxx

src/Graphic3d/Graphic3d_CStructure.hxx

@@ -22,6 +22,7 @@
 #include <Graphic3d_ViewAffinity.hxx>
 #include <Graphic3d_TransformPers.hxx>
 #include <Graphic3d_ZLayerId.hxx>
+#include <Graphic3d_ViewOcclusionMask.hxx>
 #include <TopLoc_Datum3D.hxx>
 #include <NCollection_IndexedMap.hxx>
 
@@ -173,6 +174,19 @@ public:
   //! The method is called during traverse of BVH tree.
   void MarkAsNotCulled() const { myIsCulled = Standard_False; }
 
+  //! Returns true if the structure occluded in specified view, otherwise
+  //! returns false.
+  Standard_Boolean IsOccluded(const Standard_Integer theViewId) const
+  {
+    return (!OcclusionMask->IsVisible(theViewId));
+  }
+
+  //! Marks structure as Occluded by other structure in specified view,!
+  void SetOcclusionSate(const Standard_Integer theViewId, const bool theIsVisible) const
+  {
+    OcclusionMask->SetVisible(theViewId, !theIsVisible);
+  }
+
   //! Returns whether check of object's bounding box clipping is enabled before drawing of object;
   //! TRUE by default.
   Standard_Boolean BndBoxClipCheck() const { return myBndBoxClipCheck; }
@@ -227,7 +241,8 @@ public:
                                         Standard_Integer  theDepth = -1) const;
 
 public:
-  Handle(Graphic3d_ViewAffinity) ViewAffinity; //!< view affinity mask
+  Handle(Graphic3d_ViewAffinity)      ViewAffinity;  //!< view affinity mask
+  Handle(Graphic3d_ViewOcclusionMask) OcclusionMask; //!< view occlusion mask
 
 protected:
   //! Create empty structure.

src/Graphic3d/Graphic3d_CView.cxx

@@ -533,6 +533,18 @@ void Graphic3d_CView::DisplayedStructures(Graphic3d_MapOfStructure& theStructure
 
 //=================================================================================================
 
+void Graphic3d_CView::OccludedStructures(Graphic3d_MapOfStructure& theStructures) const
+{
+  for (Graphic3d_MapOfStructure::Iterator aStructIter(myStructsDisplayed); aStructIter.More();
+       aStructIter.Next())
+  {
+    if (aStructIter.Value()->CStructure()->IsOccluded(this->myId))
+      theStructures.Add(aStructIter.Key());
+  }
+}
+
+//=================================================================================================
+
 Bnd_Box Graphic3d_CView::MinMaxValues(const Standard_Boolean theToIncludeAuxiliary) const
 {
   if (!IsDefined())

src/Graphic3d/Graphic3d_CView.hxx

@@ -154,6 +154,12 @@ public:
   //! Returns the set of structures displayed in this view.
   Standard_EXPORT void DisplayedStructures(Graphic3d_MapOfStructure& theStructures) const;
 
+  //! Returns number of occluded structures in the view
+  Standard_EXPORT void OccludedStructures(Graphic3d_MapOfStructure& theStructures) const;
+
+  //! Update occlusion test for displayed structures in the view
+  Standard_EXPORT virtual void UpdateOcclusion() = 0;
+
   //! Returns number of displayed structures in the view.
   virtual Standard_Integer NumberOfDisplayedStructures() const
   {

src/Graphic3d/Graphic3d_FrameStatsTimer.hxx

@@ -22,11 +22,12 @@ enum Graphic3d_FrameStatsTimer
   Graphic3d_FrameStatsTimer_CpuCulling,
   Graphic3d_FrameStatsTimer_CpuPicking,
   Graphic3d_FrameStatsTimer_CpuDynamics,
+  Graphic3d_FrameStatsTimer_OcclusionCulling,
 };
 
 enum
 {
-  Graphic3d_FrameStatsTimer_NB = Graphic3d_FrameStatsTimer_CpuDynamics + 1
+  Graphic3d_FrameStatsTimer_NB = Graphic3d_FrameStatsTimer_OcclusionCulling + 1
 };
 
 #endif // _Graphic3d_FrameStatsTimer_HeaderFile

src/Graphic3d/Graphic3d_RenderingParams.cxx

@@ -64,6 +64,7 @@ void Graphic3d_RenderingParams::DumpJson(Standard_OStream& theOStream,
   OCCT_DUMP_FIELD_VALUE_NUMERICAL(theOStream, CameraApertureRadius)
   OCCT_DUMP_FIELD_VALUE_NUMERICAL(theOStream, CameraFocalPlaneDist)
   OCCT_DUMP_FIELD_VALUE_NUMERICAL(theOStream, FrustumCullingState)
+  OCCT_DUMP_FIELD_VALUE_NUMERICAL(theOStream, OcclusionQueryState)
 
   OCCT_DUMP_FIELD_VALUE_NUMERICAL(theOStream, ToneMappingMethod)
   OCCT_DUMP_FIELD_VALUE_NUMERICAL(theOStream, Exposure)

src/Graphic3d/Graphic3d_RenderingParams.hxx

@@ -98,6 +98,15 @@ public:
     FrustumCulling_NoUpdate //!< culling is active, but the list of culled entities is not updated
   };
 
+  //! State of occlusion query
+  enum OcclusionQuery
+  {
+    OcclusionQuery_Off,     //!< occlusion query is disabled
+    OcclusionQuery_On,      //!< occlusion query is active
+    OcclusionQuery_NoUpdate //!< occlusion query is active, but the list of occluded entities is not
+                            //!< updated
+  };
+
 public:
   //! Creates default rendering parameters.
   Graphic3d_RenderingParams()
@@ -144,6 +153,7 @@ public:
         CameraApertureRadius(0.0f),
         CameraFocalPlaneDist(1.0f),
         FrustumCullingState(FrustumCulling_On),
+        OcclusionQueryState(OcclusionQuery_On),
         ToneMappingMethod(Graphic3d_ToneMappingMethod_Disabled),
         Exposure(0.f),
         WhitePoint(1.f),
@@ -258,6 +268,7 @@ public: //! @name Ray-Tracing/Path-Tracing parameters
   Standard_ShortReal                CameraApertureRadius;        //!< aperture radius of perspective camera used for depth-of-field, 0.0 by default (no DOF) (path tracing only)
   Standard_ShortReal                CameraFocalPlaneDist;        //!< focal  distance of perspective camera used for depth-of field, 1.0 by default (path tracing only)
   FrustumCulling                    FrustumCullingState;         //!< state of frustum culling optimization; FrustumCulling_On by default
+  OcclusionQuery                    OcclusionQueryState;         //!< state of occlusion query; OcclusionQuery_OFF by default
 
   Graphic3d_ToneMappingMethod       ToneMappingMethod;           //!< specifies tone mapping method for path tracing, Graphic3d_ToneMappingMethod_Disabled by default
   Standard_ShortReal                Exposure;                    //!< exposure value used for tone mapping (path tracing), 0.0 by default

src/Graphic3d/Graphic3d_ViewOcclusionMask.hxx

@@ -0,0 +1,25 @@
+// Created on: 2024-02-20
+// Created by: Hossam Ali
+// Copyright (c) 2024 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in
+// OCCT distribution for complete text of the license and disclaimer of any
+// warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#ifndef _Graphic3d_ViewOcclusionMask_HeaderFile
+#define _Graphic3d_ViewOcclusionMask_HeaderFile
+
+#include <Graphic3d_ViewAffinity.hxx>
+
+//! define occlusion mask as alias for view affinity mask .
+typedef Graphic3d_ViewAffinity Graphic3d_ViewOcclusionMask;
+
+#endif //_Graphic3d_ViewOcclusionMask_HeaderFile

src/OpenGl/FILES

@@ -153,3 +153,5 @@ OpenGl_TextBuilder.hxx
 OpenGl_TextBuilder.cxx
 OpenGl_HaltonSampler.hxx
 OpenGl_ShaderProgramDumpLevel.hxx
+OpenGl_OcclusionQuery.hxx
+OpenGl_OcclusionQuery.cxx

src/OpenGl/OpenGl_LayerList.cxx

@@ -25,6 +25,7 @@
 #include <OpenGl_VertexBuffer.hxx>
 #include <OpenGl_View.hxx>
 #include <OpenGl_Workspace.hxx>
+#include <OpenGl_OcclusionQuery.hxx>
 
 namespace
 {
@@ -894,10 +895,78 @@ void OpenGl_LayerList::Render(const Handle(OpenGl_Workspace)& theWorkspace,
   theWorkspace->SetRenderFilter(aPrevFilter);
 }
 
-//=======================================================================
-// function : renderTransparent
-// purpose  : Render transparent objects using blending operator.
-//=======================================================================
+//=================================================================================================
+
+void OpenGl_LayerList::UpdateOcclusion(const Handle(OpenGl_Workspace)& theWorkspace)
+{
+  const Handle(OpenGl_Context)& aCtx = theWorkspace->GetGlContext();
+  aCtx->core11fwd->glEnable(GL_DEPTH_TEST);
+  aCtx->core11fwd->glDepthFunc(GL_LESS);
+
+  // Remember global settings for glDepth mask and write mask
+  GLboolean aPrevColorMask[4];
+  GLboolean aPrevDepthMask;
+  aCtx->core11fwd->glGetBooleanv(GL_COLOR_WRITEMASK, aPrevColorMask);
+  aCtx->core11fwd->glGetBooleanv(GL_DEPTH_WRITEMASK, &aPrevDepthMask);
+
+  // Turn off writing to depth and color buffers
+  aCtx->core11fwd->glColorMask(GL_FALSE, GL_FALSE, GL_FALSE, GL_FALSE);
+
+  // Start record occlusion test computational cost
+  const Handle(OpenGl_FrameStats)& aStats = theWorkspace->GetGlContext()->FrameStats();
+  OSD_Timer&                       aTimer =
+    aStats->ActiveDataFrame().ChangeTimer(Graphic3d_FrameStatsTimer_OcclusionCulling);
+  aTimer.Start();
+
+  // Loop for all layers
+  for (NCollection_List<Handle(Graphic3d_Layer)>::Iterator aLayerIter(myLayers); aLayerIter.More();
+       aLayerIter.Next())
+  {
+
+    const Handle(Graphic3d_Layer)& aLayer = aLayerIter.ChangeValue();
+
+    // Exclude frustum culled layer
+    if (aLayer->IsCulled())
+      continue;
+
+    aCtx->core11fwd->glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+
+    // Render priority list
+    const Standard_Integer aViewId = theWorkspace->View()->Identification();
+
+    for (Standard_Integer aPriorityIter = Graphic3d_DisplayPriority_Bottom;
+         aPriorityIter <= Graphic3d_DisplayPriority_Topmost;
+         ++aPriorityIter)
+    {
+      const Graphic3d_IndexedMapOfStructure& aStructures =
+        aLayer->Structures((Graphic3d_DisplayPriority)aPriorityIter);
+      for (OpenGl_Structure::StructIterator aStructIter(aStructures); aStructIter.More();
+           aStructIter.Next())
+      {
+        const OpenGl_Structure* aStruct = aStructIter.Value();
+
+        // Exclude view frustum culled structs
+        if (aStruct->IsCulled() || !aStruct->IsVisible(aViewId) || aStruct->IsForHighlight)
+          continue;
+
+        aStruct->UpdateOcclusion(theWorkspace);
+      }
+    }
+  }
+
+  // Back to prev settings
+  aCtx->core11fwd->glDepthMask(aPrevDepthMask);
+  aCtx->core11fwd->glColorMask(aPrevColorMask[0],
+                               aPrevColorMask[1],
+                               aPrevColorMask[2],
+                               aPrevColorMask[3]);
+
+  aTimer.Stop();
+  aStats->ActiveDataFrame()[Graphic3d_FrameStatsTimer_CpuCulling] = aTimer.UserTimeCPU();
+}
+
+//=================================================================================================
+
 void OpenGl_LayerList::renderTransparent(const Handle(OpenGl_Workspace)&   theWorkspace,
                                          OpenGl_LayerStack::iterator&      theLayerIter,
                                          const OpenGl_GlobalLayerSettings& theGlobalSettings,

src/OpenGl/OpenGl_LayerList.hxx

@@ -109,6 +109,9 @@ public:
                               OpenGl_FrameBuffer*             theReadDrawFbo,
                               OpenGl_FrameBuffer*             theOitAccumFbo) const;
 
+  //! Update occlusion test
+  Standard_EXPORT void UpdateOcclusion(const Handle(OpenGl_Workspace)& theWorkspace);
+
   //! Returns the set of OpenGL Z-layers.
   const NCollection_List<Handle(Graphic3d_Layer)>& Layers() const { return myLayers; }
 

src/OpenGl/OpenGl_OcclusionQuery.cxx

@@ -0,0 +1,101 @@
+// Created on: 2024-02-20
+// Created by: Hossam Ali
+// Copyright (c) 2024 OPEN CASCADE SAS
+//
+// This file is part of Open CASCADE Technology software library.
+//
+// This library is free software; you can redistribute it and/or modify it under
+// the terms of the GNU Lesser General Public License version 2.1 as published
+// by the Free Software Foundation, with special exception defined in the file
+// OCCT_LGPL_EXCEPTION.txt. Consult the file LICENSE_LGPL_21.txt included in
+// OCCT distribution for complete text of the license and disclaimer of any
+// warranty.
+//
+// Alternatively, this file may be used under the terms of Open CASCADE
+// commercial license or contractual agreement.
+
+#include <OpenGl_OcclusionQuery.hxx>
+
+#include <OpenGl_Context.hxx>
+#include <OpenGl_GlCore15.hxx>
+
+IMPLEMENT_STANDARD_RTTIEXT(OpenGl_OcclusionQuery, OpenGl_Resource)
+
+//=================================================================================================
+
+OpenGl_OcclusionQuery::OpenGl_OcclusionQuery()
+    : myID(0),
+      inUse(false),
+      started(false)
+{
+}
+
+//=================================================================================================
+
+OpenGl_OcclusionQuery::~OpenGl_OcclusionQuery()
+{
+  Release(NULL);
+}
+
+//=================================================================================================
+
+void OpenGl_OcclusionQuery::Create(const Handle(OpenGl_Context)& theCtx, GLenum theQueryType)
+{
+  theCtx->core15->glGenQueries(1, &myID);
+  myType  = theQueryType;
+  inUse   = false;
+  started = false;
+}
+
+//=================================================================================================
+
+void OpenGl_OcclusionQuery::Begin(const Handle(OpenGl_Context)& theCtx)
+{
+  inUse   = true;
+  started = true;
+  theCtx->core15->glBeginQuery(myType, myID);
+}
+
+//=================================================================================================
+
+void OpenGl_OcclusionQuery::End(const Handle(OpenGl_Context)& theCtx) const
+{
+  theCtx->core15->glEndQuery(myType);
+}
+
+//=================================================================================================
+
+int OpenGl_OcclusionQuery::IsResultsReady(const Handle(OpenGl_Context)& theCtx) const
+{
+  // check if the query started before check for results
+  if (!started)
+    return false;
+
+  GLint aReady = 0;
+  theCtx->core15->glGetQueryObjectiv(myID, GL_QUERY_RESULT_AVAILABLE, &aReady);
+  return aReady;
+}
+
+//=================================================================================================
+
+int OpenGl_OcclusionQuery::GetResults(const Handle(OpenGl_Context)& theCtx)
+{
+  inUse = false;
+  GLint aResult;
+  theCtx->core15->glGetQueryObjectiv(myID, GL_QUERY_RESULT, &aResult);
+  return aResult;
+}
+
+//=================================================================================================
+
+void OpenGl_OcclusionQuery::Release(OpenGl_Context* theCtx)
+{
+  if (myID == 0)
+    return;
+  if (theCtx != NULL)
+  {
+    theCtx->core15->glDeleteQueries(1, &myID);
+    myID    = 0;
+    started = false;
+  }
+}