0029974: Visualization - OpenGl_Layer::Render() produces inconsistent state of Polygon Offset settings

OpenGl_Layer::Render() now calls OpenGl_Workspace::SetDefaultPolygonOffset()
for managing default polygon offset settings considering OpenGl_Workspace applied aspect logic.

src/Graphic3d/Graphic3d_AspectFillArea3d.hxx

@@ -214,6 +214,9 @@ public:
   //! Returns current polygon offsets settings.
   const Graphic3d_PolygonOffset& PolygonOffset() const { return myPolygonOffset; }
 
+  //! Sets polygon offsets settings.
+  void SetPolygonOffset (const Graphic3d_PolygonOffset& theOffset) { myPolygonOffset = theOffset; }
+
   //! Returns current polygon offsets settings.
   void PolygonOffsets (Standard_Integer&   theMode,
                        Standard_ShortReal& theFactor,

src/OpenGl/OpenGl_Layer.cxx

@@ -656,7 +656,6 @@ void OpenGl_Layer::Render (const Handle(OpenGl_Workspace)&   theWorkspace,
                            const OpenGl_GlobalLayerSettings& theDefaultSettings) const
 {
   const Handle(OpenGl_Context)& aCtx = theWorkspace->GetGlContext();
-  const Graphic3d_PolygonOffset anAppliedOffsetParams = aCtx->PolygonOffset();
   // myLayerSettings.ToClearDepth() is handled outside
 
   // handle depth test
@@ -678,7 +677,7 @@ void OpenGl_Layer::Render (const Handle(OpenGl_Workspace)&   theWorkspace,
   }
 
   // handle depth offset
-  aCtx->SetPolygonOffset (myLayerSettings.PolygonOffset());
+  const Graphic3d_PolygonOffset anAppliedOffsetParams = theWorkspace->SetDefaultPolygonOffset (myLayerSettings.PolygonOffset());
 
   // handle depth write
   theWorkspace->UseDepthWrite() = myLayerSettings.ToEnableDepthWrite() && theDefaultSettings.DepthMask == GL_TRUE;
@@ -759,7 +758,7 @@ void OpenGl_Layer::Render (const Handle(OpenGl_Workspace)&   theWorkspace,
   }
 
   // always restore polygon offset between layers rendering
-  aCtx->SetPolygonOffset (anAppliedOffsetParams);
+  theWorkspace->SetDefaultPolygonOffset (anAppliedOffsetParams);
 
   // restore environment texture
   if (!myLayerSettings.UseEnvironmentTexture())

src/OpenGl/OpenGl_Workspace.cxx

@@ -43,11 +43,6 @@ namespace
   static const OpenGl_Vec4 THE_WHITE_COLOR (1.0f, 1.0f, 1.0f, 1.0f);
   static const OpenGl_Vec4 THE_BLACK_COLOR (0.0f, 0.0f, 0.0f, 1.0f);
 
-  static const OpenGl_AspectLine myDefaultAspectLine;
-  static const OpenGl_AspectFace myDefaultAspectFace;
-  static const OpenGl_AspectMarker myDefaultAspectMarker;
-  static const OpenGl_AspectText myDefaultAspectText;
-
   static const OpenGl_Matrix myDefaultMatrix =
   {
     {{ 1.0F, 0.0F, 0.0F, 0.0F },
@@ -228,6 +223,23 @@ void OpenGl_Workspace::ResetAppliedAspect()
   myGlContext->SetLineWidth  (myDefaultAspectLine.Aspect()->Width());
 }
 
+// =======================================================================
+// function : SetDefaultPolygonOffset
+// purpose  :
+// =======================================================================
+Graphic3d_PolygonOffset OpenGl_Workspace::SetDefaultPolygonOffset (const Graphic3d_PolygonOffset& theOffset)
+{
+  Graphic3d_PolygonOffset aPrev = myDefaultAspectFace.Aspect()->PolygonOffset();
+  myDefaultAspectFace.Aspect()->SetPolygonOffset (theOffset);
+  if (myAspectFaceApplied == myDefaultAspectFace.Aspect()
+   || myAspectFaceApplied.IsNull()
+   || (myAspectFaceApplied->PolygonOffset().Mode & Aspect_POM_None) == Aspect_POM_None)
+  {
+    myGlContext->SetPolygonOffset (theOffset);
+  }
+  return aPrev;
+}
+
 // =======================================================================
 // function : SetAspectLine
 // purpose  :

src/OpenGl/OpenGl_Workspace.hxx

@@ -86,6 +86,10 @@ public:
   //! @return true if frustum culling algorithm is enabled
   Standard_EXPORT Standard_Boolean IsCullingEnabled() const;
 
+  //! Configure default polygon offset parameters.
+  //! Return previous settings.
+  Standard_EXPORT Graphic3d_PolygonOffset SetDefaultPolygonOffset (const Graphic3d_PolygonOffset& theOffset);
+
   //// RELATED TO STATUS ////
 
   //! Return true if active group might activate face culling (e.g. primitives are closed).
@@ -259,6 +263,11 @@ protected: //! @name fields related to status
   Standard_Integer myNbSkippedTranspElems; //!< counter of skipped transparent elements for OpenGl_LayerList two rendering passes method
   Standard_Integer myRenderFilter;         //!< active filter for skipping rendering of elements by some criteria (multiple render passes)
 
+  OpenGl_AspectLine   myDefaultAspectLine;
+  OpenGl_AspectFace   myDefaultAspectFace;
+  OpenGl_AspectMarker myDefaultAspectMarker;
+  OpenGl_AspectText   myDefaultAspectText;
+
   const OpenGl_AspectLine*   myAspectLineSet;
   const OpenGl_AspectFace*   myAspectFaceSet;
   Handle(Graphic3d_AspectFillArea3d) myAspectFaceApplied;