0027700: Visualization - glPolygonMode() used for frame drawing affects label text shading

Patch extends GL-state caching mechanism of OpenGl_Context by new methods.
The methods allow setting/inquiring polygon rasterization and hatching modes:
- OpenGl_Context::SetPolygonMode
- OpenGl_Context::SetPolygonHatchEnabled
- OpenGl_Context::SetPolygonHatchStyle

With these methods OpenGl_Text is able to configure shading as necessary.
And this configuration is done irrespectively of currently defined face aspect.
Code of OpenGl_Workspace is also modified to use these methods as well.

Porting notes:
- OpenGl_LineAttributes now require OpenGl_Context instance for calling GL API.
- OpenGl_LineAttributes has new flag IsEnabled, it turns on/off hatching without changing the hatch type.
  By default this flag is turned on and can be never modified for compatibility with old code.
- OpenGl_LineAttributes is not anymore a field of OpenGl_Workspace::myLineAttrib.
  This resource is directly created by an OpenGl_Context instance on demand.
  If you use custom implementation of hatch patterns please create and share custom resource
  under resource-key "OpenGl_LineAttributes" in corresponding OpenGl_Context before using
  methods SetPolygonHatchEnabled, SetPolygonHatchStyle.

src/OpenGl/OpenGl_Context.cxx

@@ -141,9 +141,11 @@ OpenGl_Context::OpenGl_Context (const Handle(OpenGl_Caps)& theCaps)
 #if !defined(GL_ES_VERSION_2_0)
   myPointSpriteOrig (GL_UPPER_LEFT),
   myRenderMode (GL_RENDER),
+  myPolygonMode (GL_FILL),
 #else
   myPointSpriteOrig (0),
   myRenderMode (0),
+  myPolygonMode (0),
 #endif
   myToCullBackFaces (false),
   myReadBuffer (0),
@@ -2844,6 +2846,70 @@ Standard_Boolean OpenGl_Context::SetGlNormalizeEnabled (Standard_Boolean isEnabl
   return anOldGlNormalize;
 }
 
+// =======================================================================
+// function : SetPolygonMode
+// purpose  :
+// =======================================================================
+Standard_Integer OpenGl_Context::SetPolygonMode (const Standard_Integer theMode)
+{
+  if (myPolygonMode == theMode)
+  {
+    return myPolygonMode;
+  }
+
+  const Standard_Integer anOldPolygonMode = myPolygonMode;
+
+  myPolygonMode = theMode;
+
+#if !defined(GL_ES_VERSION_2_0)
+  ::glPolygonMode (GL_FRONT_AND_BACK, (GLenum)theMode);
+#endif
+
+  return anOldPolygonMode;
+}
+
+// =======================================================================
+// function : SetPolygonHatchEnabled
+// purpose  :
+// =======================================================================
+bool OpenGl_Context::SetPolygonHatchEnabled (const bool theIsEnabled)
+{
+  if (myHatchStyles.IsNull())
+  {
+    return false;
+  }
+  else if (myHatchStyles->IsEnabled() == theIsEnabled)
+  {
+    return theIsEnabled;
+  }
+
+  return myHatchStyles->SetEnabled (this, theIsEnabled);
+}
+
+// =======================================================================
+// function : SetPolygonHatchStyle
+// purpose  :
+// =======================================================================
+Standard_Integer OpenGl_Context::SetPolygonHatchStyle (const Standard_Integer theType)
+{
+  if (myHatchStyles.IsNull())
+  {
+    if (!GetResource ("OpenGl_LineAttributes", myHatchStyles))
+    {
+      // share and register for release once the resource is no longer used
+      myHatchStyles = new OpenGl_LineAttributes();
+      ShareResource ("OpenGl_LineAttributes", myHatchStyles);
+      myHatchStyles->Init (this);
+    }
+  }
+  if (myHatchStyles->TypeOfHatch() == theType)
+  {
+    return theType;
+  }
+
+  return myHatchStyles->SetTypeOfHatch (this, theType);
+}
+
 // =======================================================================
 // function : ApplyModelWorldMatrix
 // purpose  :