[occt.git] / src / OpenGl / OpenGl_View.hxx

// Created on: 2011-09-20
// Created by: Sergey ZERCHANINOV
// Copyright (c) 2011-2014 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 _OpenGl_View_Header
#define _OpenGl_View_Header

#include <MMgt_TShared.hxx>
#include <Standard_Type.hxx>

#include <TColStd_Array2OfReal.hxx>
#include <NCollection_List.hxx>
#include <math_BullardGenerator.hxx>

#include <Quantity_NameOfColor.hxx>
#include <Aspect_FillMethod.hxx>
#include <Aspect_GradientFillMethod.hxx>
#include <Aspect_TypeOfTriedronPosition.hxx>

#include <InterfaceGraphic_Graphic3d.hxx>

#include <Graphic3d_CView.hxx>
#include <Graphic3d_GraduatedTrihedron.hxx>
#include <Graphic3d_SequenceOfHClipPlane.hxx>
#include <Graphic3d_TypeOfShadingModel.hxx>
#include <Graphic3d_TypeOfSurfaceDetail.hxx>
#include <Graphic3d_WorldViewProjState.hxx>
#include <Graphic3d_ZLayerSettings.hxx>

#include <OpenGl_AspectFace.hxx>
#include <OpenGl_BackgroundArray.hxx>
#include <OpenGl_BVHTreeSelector.hxx>
#include <OpenGl_Context.hxx>
#include <OpenGl_FrameBuffer.hxx>
#include <OpenGl_GraduatedTrihedron.hxx>
#include <OpenGl_LayerList.hxx>
#include <OpenGl_Light.hxx>
#include <OpenGl_LineAttributes.hxx>
#include <OpenGl_SceneGeometry.hxx>
#include <OpenGl_Structure.hxx>
#include <OpenGl_Trihedron.hxx>
#include <OpenGl_Window.hxx>
#include <OpenGl_Workspace.hxx>

#include <map>
#include <set>

struct OPENGL_ZCLIP
{
  struct {
    Standard_Boolean   IsOn;
    Standard_ShortReal Limit; /* in the range [0., 1.] */
  } Back;
  struct {
    Standard_Boolean   IsOn;
    Standard_ShortReal Limit; /* in the range [0., 1.] */
  } Front;
};

struct OPENGL_FOG
{
  Standard_Boolean   IsOn;
  Standard_ShortReal Front; /* in the range [0., 1.] */
  Standard_ShortReal Back; /* in the range [0., 1.] */
  TEL_COLOUR         Color;
};

struct OpenGl_Matrix;

class Graphic3d_StructureManager;
class OpenGl_GraphicDriver;
class OpenGl_StateCounter;
class OpenGl_RaytraceMaterial;
class OpenGl_TriangleSet;
class OpenGl_Workspace;
class OpenGl_View;
DEFINE_STANDARD_HANDLE(OpenGl_View,Graphic3d_CView)

//! Implementation of OpenGl view.
class OpenGl_View : public Graphic3d_CView
{

public:

  //! Constructor.
  Standard_EXPORT OpenGl_View (const Handle(Graphic3d_StructureManager)& theMgr,
                               const Handle(OpenGl_GraphicDriver)& theDriver,
                               const Handle(OpenGl_Caps)& theCaps,
                               Standard_Boolean& theDeviceLostFlag,
                               OpenGl_StateCounter* theCounter);

  //! Default destructor.
  Standard_EXPORT virtual ~OpenGl_View();

  Standard_EXPORT void ReleaseGlResources (const Handle(OpenGl_Context)& theCtx);

  //! Deletes and erases the view.
  Standard_EXPORT virtual void Remove() Standard_OVERRIDE;

  //! @param theDrawToFrontBuffer Advanced option to modify rendering mode:
  //! 1. TRUE.  Drawing immediate mode structures directly to the front buffer over the scene image.
  //! Fast, so preferred for interactive work (used by default).
  //! However these extra drawings will be missed in image dump since it is performed from back buffer.
  //! Notice that since no pre-buffering used the V-Sync will be ignored and rendering could be seen
  //! in run-time (in case of slow hardware) and/or tearing may appear.
  //! So this is strongly recommended to draw only simple (fast) structures.
  //! 2. FALSE. Drawing immediate mode structures to the back buffer.
  //! The complete scene is redrawn first, so this mode is slower if scene contains complex data and/or V-Sync
  //! is turned on. But it works in any case and is especially useful for view dump because the dump image is read
  //! from the back buffer.
  //! @return previous mode.
  Standard_EXPORT Standard_Boolean SetImmediateModeDrawToFront (const Standard_Boolean theDrawToFrontBuffer) Standard_OVERRIDE;

  //! Creates and maps rendering window to the view.
  //! @param theWindow [in] the window.
  //! @param theContext [in] the rendering context. If NULL the context will be created internally.
  Standard_EXPORT virtual void SetWindow (const Handle(Aspect_Window)&  theWindow,
                                          const Aspect_RenderingContext theContext) Standard_OVERRIDE;

  //! Returns window associated with the view.
  virtual Handle(Aspect_Window) Window() const Standard_OVERRIDE { return myWindow->PlatformWindow(); }

  //! Returns True if the window associated to the view is defined.
  virtual Standard_Boolean IsDefined() const { return !myWindow.IsNull(); }

  //! Handle changing size of the rendering window.
  Standard_EXPORT virtual void Resized() Standard_OVERRIDE;

  //! Redraw content of the view.
  Standard_EXPORT virtual void Redraw() Standard_OVERRIDE;

  //! Redraw immediate content of the view.
  Standard_EXPORT virtual void RedrawImmediate() Standard_OVERRIDE;

  //! Marks BVH tree for given priority list as dirty and marks primitive set for rebuild.
  Standard_EXPORT virtual void Invalidate() Standard_OVERRIDE;

  //! Return true if view content cache has been invalidated.
  virtual Standard_Boolean IsInvalidated() Standard_OVERRIDE { return myBackBufferRestored; }

  //! Displays z-buffer trihedron.
  Standard_EXPORT virtual void TriedronDisplay (const Aspect_TypeOfTriedronPosition thePosition = Aspect_TOTP_CENTER,
                                                const Quantity_NameOfColor theColor = Quantity_NOC_WHITE,
                                                const Standard_Real theScale = 0.02,
                                                const Standard_Boolean theAsWireframe = Standard_True) Standard_OVERRIDE;

  //! Erases z-buffer trihedron.
  Standard_EXPORT virtual void TriedronErase() Standard_OVERRIDE;

  //! Setup parameters of z-buffer trihedron.
  Standard_EXPORT virtual void ZBufferTriedronSetup (const Quantity_NameOfColor theXColor = Quantity_NOC_RED,
                                                     const Quantity_NameOfColor theYColor = Quantity_NOC_GREEN,
                                                     const Quantity_NameOfColor theZColor = Quantity_NOC_BLUE1,
                                                     const Standard_Real theSizeRatio = 0.8,
                                                     const Standard_Real theAxisDiametr = 0.05,
                                                     const Standard_Integer theNbFacettes = 12) Standard_OVERRIDE;

  //! Displays trihedron echo.
  Standard_EXPORT virtual void TriedronEcho (const Aspect_TypeOfTriedronEcho theType = Aspect_TOTE_NONE) Standard_OVERRIDE;

  //! Returns data of a graduated trihedron
  const Graphic3d_GraduatedTrihedron& GetGraduatedTrihedron() { return myGTrihedronData; }

  //! Displays Graduated Trihedron.
  Standard_EXPORT virtual void GraduatedTrihedronDisplay (const Graphic3d_GraduatedTrihedron& theTrihedronData) Standard_OVERRIDE;

  //! Erases Graduated Trihedron.
  Standard_EXPORT virtual void GraduatedTrihedronErase() Standard_OVERRIDE;

  //! Sets minimum and maximum points of scene bounding box for Graduated Trihedron stored in graphic view object.
  //! @param theMin [in] the minimum point of scene.
  //! @param theMax [in] the maximum point of scene.
  Standard_EXPORT virtual void GraduatedTrihedronMinMaxValues (const Graphic3d_Vec3 theMin, const Graphic3d_Vec3 theMax) Standard_OVERRIDE;

  //! Reads depths of shown pixels of the given rectangle.
  Standard_EXPORT virtual void ReadDepths (const Standard_Integer theX,
                                           const Standard_Integer theY,
                                           const Standard_Integer theWidth,
                                           const Standard_Integer theHeight,
                                           const Standard_Address theBuffer) const Standard_OVERRIDE;

  //! Dump active rendering buffer into specified memory buffer.
  Standard_EXPORT virtual Standard_Boolean BufferDump (Image_PixMap& theImage,
                                                       const Graphic3d_BufferType& theBufferType) Standard_OVERRIDE;

  //! Print the contents of the view to the printer.
  //! @param thePrinterDC        pass the PrinterDeviceContext (HDC)
  //! @param theToShowBackground when set to FALSE then print the view without background
  //!                            color (background is white) else set to TRUE for printing
  //!                            with current background color
  //! @param theFileName         if != NULL, then the view will be printed to a file
  //! @param thePrintAlgorithm   select print algorithm: stretch, tile
  //! @param theScaleFactor      scaling coefficient, used internally to scale the printings
  //!                            accordingly to the scale factor selected in the printer properties dialog
  //! @return Standard_True if the data is passed to the printer, otherwise Standard_False if
  //! the print operation failed due to the printer errors, or lack of system memory. This might be related
  //! to insufficient memory or some internal errors.
  //! All this errors are indicated by the message boxes (on level of OpenGl_GraphicDriver).
  //! Warning: This function can reuse FBO assigned to the view, please take it into account
  //! if you use it for your purposes.
  Standard_EXPORT virtual Standard_Boolean Print (const Aspect_Handle    thePrinterDC,
                                                  const Standard_Boolean theToShowBackground,
                                                  const Standard_CString theFileName,
                                                  const Aspect_PrintAlgo thePrintAlgorithm = Aspect_PA_STRETCH,
                                                  const Standard_Real    theScaleFactor = 1.0) Standard_OVERRIDE;

  //! Export scene into the one of the Vector graphics formats (SVG, PS, PDF...).
  //! In contrast to Bitmaps, Vector graphics is scalable (so you may got quality benefits
  //! on printing to laser printer). Notice however that results may differ a lot and
  //! do not contain some elements.
  Standard_EXPORT virtual Standard_Boolean Export (const Standard_CString theFileName,
                                                   const Graphic3d_ExportFormat theFormat,
                                                   const Graphic3d_SortType theSortType = Graphic3d_ST_BSP_Tree) Standard_OVERRIDE;

  //! Marks BVH tree and the set of BVH primitives of correspondent priority list with id theLayerId as outdated.
  Standard_EXPORT virtual void InvalidateBVHData (const Standard_Integer theLayerId) Standard_OVERRIDE;

  //! Insert a new top-level z layer with the given ID.
  Standard_EXPORT virtual void AddZLayer (const Graphic3d_ZLayerId theLayerId) Standard_OVERRIDE;

  //! Remove a z layer with the given ID.
  Standard_EXPORT virtual void RemoveZLayer (const Graphic3d_ZLayerId theLayerId) Standard_OVERRIDE;

  //! Sets the settings for a single Z layer of specified view.
  Standard_EXPORT virtual void SetZLayerSettings (const Graphic3d_ZLayerId theLayerId,
                                                  const Graphic3d_ZLayerSettings& theSettings) Standard_OVERRIDE;

  //! Returns pointer to an assigned framebuffer object.
  Standard_EXPORT virtual Graphic3d_PtrFrameBuffer FBO() const Standard_OVERRIDE;

  //! Sets framebuffer object for offscreen rendering.
  Standard_EXPORT virtual void SetFBO (const Graphic3d_PtrFrameBuffer theFBO) Standard_OVERRIDE;

  //! Generate offscreen FBO in the graphic library.
  //! If not supported on hardware returns NULL.
  Standard_EXPORT virtual Graphic3d_PtrFrameBuffer FBOCreate (const Standard_Integer theWidth,
                                                              const Standard_Integer theHeight) Standard_OVERRIDE;

  //! Remove offscreen FBO from the graphic library
  Standard_EXPORT virtual void FBORelease (Graphic3d_PtrFrameBuffer& theFBOPtr) Standard_OVERRIDE;

  //! Read offscreen FBO configuration.
  Standard_EXPORT virtual void FBOGetDimensions (const Graphic3d_PtrFrameBuffer theFBOPtr,
                                                 Standard_Integer& theWidth,
                                                 Standard_Integer& theHeight,
                                                 Standard_Integer& theWidthMax,
                                                 Standard_Integer& theHeightMax) Standard_OVERRIDE;

  //! Change offscreen FBO viewport.
  Standard_EXPORT virtual void FBOChangeViewport (Graphic3d_PtrFrameBuffer& theFBOPtr,
                                                  const Standard_Integer theWidth,
                                                  const Standard_Integer theHeight) Standard_OVERRIDE;

public:

  //! Returns true if anti-aliasing is enabled for the view.
  Standard_Boolean virtual IsAntialiasingEnabled() const Standard_OVERRIDE { return myAntiAliasing; }

  //! Enable or disable anti-aliasing in the view.
  virtual void SetAntialiasingEnabled (const Standard_Boolean theIsEnabled) Standard_OVERRIDE { myAntiAliasing = theIsEnabled; }

  //! Returns background  fill color.
  Standard_EXPORT virtual Aspect_Background Background() const Standard_OVERRIDE;

  //! Sets background fill color.
  Standard_EXPORT virtual void SetBackground (const Aspect_Background& theBackground) Standard_OVERRIDE;

  //! Returns gradient background fill colors.
  Standard_EXPORT virtual Aspect_GradientBackground GradientBackground() const Standard_OVERRIDE;

  //! Sets gradient background fill colors.
  Standard_EXPORT virtual void SetGradientBackground (const Aspect_GradientBackground& theBackground) Standard_OVERRIDE;

  //! Returns background image texture file path.
  Standard_EXPORT virtual TCollection_AsciiString BackgroundImage() Standard_OVERRIDE { return myBackgroundImagePath; }

  //! Sets background image texture file path.
  Standard_EXPORT virtual void SetBackgroundImage (const TCollection_AsciiString& theFilePath) Standard_OVERRIDE;

  //! Returns background image fill style.
  Standard_EXPORT virtual Aspect_FillMethod BackgroundImageStyle() const Standard_OVERRIDE;

  //! Sets background image fill style.
  Standard_EXPORT virtual void SetBackgroundImageStyle (const Aspect_FillMethod theFillStyle) Standard_OVERRIDE;

  //! Returns environment texture set for the view.
  Standard_EXPORT virtual Handle(Graphic3d_TextureEnv) TextureEnv() const Standard_OVERRIDE { return myTextureEnvData; }

  //! Sets environment texture for the view.
  Standard_EXPORT virtual void SetTextureEnv (const Handle(Graphic3d_TextureEnv)& theTextureEnv) Standard_OVERRIDE;

  //! Returns the state of frustum culling optimization.
  virtual Standard_Boolean IsCullingEnabled() const Standard_OVERRIDE { return myCulling; }

  //! Enables or disables frustum culling optimization.
  virtual void SetCullingEnabled (const Standard_Boolean theIsEnabled) Standard_OVERRIDE { myCulling = theIsEnabled; }

  //! Returns shading model of the view.
  virtual Graphic3d_TypeOfShadingModel ShadingModel() const Standard_OVERRIDE { return myShadingModel; }

  //! Sets shading model of the view.
  virtual void SetShadingModel (const Graphic3d_TypeOfShadingModel theModel) Standard_OVERRIDE { myShadingModel = theModel; }

  //! Returns surface detail type of the view.
  virtual Graphic3d_TypeOfSurfaceDetail SurfaceDetailType() const Standard_OVERRIDE { return mySurfaceDetail; }

  //! Sets surface detail type of the view.
  virtual void SetSurfaceDetailType (const Graphic3d_TypeOfSurfaceDetail theType) Standard_OVERRIDE
  {
    mySurfaceDetail          = theType;
    myToUpdateEnvironmentMap = Standard_True;
  }

  //! Return backfacing model used for the view.
  virtual Graphic3d_TypeOfBackfacingModel BackfacingModel() const Standard_OVERRIDE { return myBackfacing; }

  //! Sets backfacing model for the view.
  virtual void SetBackfacingModel (const Graphic3d_TypeOfBackfacingModel theModel) Standard_OVERRIDE { myBackfacing = theModel; }

  //! Returns camera object of the view.
  virtual const Handle(Graphic3d_Camera)& Camera() const Standard_OVERRIDE { return myCamera; }

  //! Sets camera used by the view.
  virtual void SetCamera (const Handle(Graphic3d_Camera)& theCamera) Standard_OVERRIDE { myCamera = theCamera; }

  //! Returns the activity of back z-clipping plane.
  virtual Standard_Boolean BackZClippingIsOn() const Standard_OVERRIDE { return myZClip.Back.IsOn; }

  //! Activates the back Z-clipping plane.
  virtual void SetBackZClippingOn (const Standard_Boolean theIsOn) Standard_OVERRIDE { myZClip.Back.IsOn = theIsOn; }

  //! Returns the definition of the back Z-clipping plane.
  virtual Standard_Real ZClippingBackPlane() const Standard_OVERRIDE { return myZClip.Back.Limit; }

  //! Sets the definition of the back Z-clipping plane.
  virtual void SetZClippingBackPlane (const Standard_Real theValue) Standard_OVERRIDE
  {
    myZClip.Back.Limit = static_cast<Standard_ShortReal> (theValue);
  }

  //! Returns the activity of front z-clipping plane.
  virtual Standard_Boolean FrontZClippingIsOn() const Standard_OVERRIDE { return myZClip.Front.IsOn; }

  //! Activates the front Z-clipping plane.
  virtual void SetFrontZClippingOn (const Standard_Boolean theIsOn) Standard_OVERRIDE{ myZClip.Front.IsOn = theIsOn; }

  //! Returns the definition of the front Z-clipping plane.
  virtual Standard_Real ZClippingFrontPlane() const Standard_OVERRIDE { return myZClip.Front.Limit; }

  //! Sets the definition of the front Z-clipping plane.
  virtual void SetZClippingFrontPlane (const Standard_Real theValue) Standard_OVERRIDE
  {
    myZClip.Front.Limit = static_cast<Standard_ShortReal> (theValue);
  }

  //! Returns the activity of depth cueing.
  virtual Standard_Boolean DepthCueingIsOn() const Standard_OVERRIDE { return myFog.IsOn; }

  //! Sets the activity of depth cueing.
  virtual void SetDepthCueingOn (const Standard_Boolean theIsOn) Standard_OVERRIDE { myFog.IsOn = theIsOn; }

  //! Returns the back depth cueing plane.
  virtual Standard_Real DepthCueingBackPlane() const Standard_OVERRIDE { return myFog.Back; }

  //! Set the back depth cueing plane.
  virtual void SetDepthCueingBackPlane (const Standard_Real theValue) Standard_OVERRIDE
  {
    myFog.Back = static_cast<Standard_ShortReal> (theValue);
  }

  //! Returns the front depth cueing plane.
  virtual Standard_Real DepthCueingFrontPlane() const Standard_OVERRIDE { return myFog.Front; }

  //! Set the front depth cueing plane.
  virtual void SetDepthCueingFrontPlane (const Standard_Real theValue) Standard_OVERRIDE
  {
    myFog.Front = static_cast<Standard_ShortReal> (theValue);
  }

  //! Returns true if GL lighting is enabled.
  virtual Standard_Boolean IsGLLightEnabled() const Standard_OVERRIDE { return myUseGLLight; }

  //! Sets GL lighting enabled or disable state.
  virtual void SetGLLightEnabled (const Standard_Boolean theIsEnabled) Standard_OVERRIDE { myUseGLLight = theIsEnabled; }

  //! Returns list of lights of the view.
  virtual const Graphic3d_ListOfCLight& Lights() const Standard_OVERRIDE { return myLights; }

  //! Sets list of lights for the view.
  virtual void SetLights (const Graphic3d_ListOfCLight& theLights) Standard_OVERRIDE
  {
    myLights = theLights;
    myCurrLightSourceState = myStateCounter->Increment();
  }

  //! Returns list of clip planes set for the view.
  virtual const Graphic3d_SequenceOfHClipPlane& ClipPlanes() const Standard_OVERRIDE { return myClipPlanes; }

  //! Sets list of clip planes for the view.
  virtual void SetClipPlanes (const Graphic3d_SequenceOfHClipPlane& thePlanes) Standard_OVERRIDE { myClipPlanes = thePlanes; }

public:

  //! Returns background color.
  const TEL_COLOUR& BackgroundColor() const { return myBgColor; }

  //! Change trihedron.
  OpenGl_Trihedron& ChangeTrihedron() { return myTrihedron; }

  //! Change graduated trihedron.
  OpenGl_GraduatedTrihedron& ChangeGraduatedTrihedron() { return myGraduatedTrihedron; }

  void SetTextureEnv (const Handle(OpenGl_Context)&       theCtx,
                      const Handle(Graphic3d_TextureEnv)& theTexture);

  //! Returns height of view volume.
  Standard_Real Height () const { return myCamera->ViewDimensions().X(); }

  //! Returns width of view volume.
  Standard_Real Width () const { return myCamera->ViewDimensions().Y(); }

  void SetBackgroundTextureStyle (const Aspect_FillMethod FillStyle);

  void SetBackgroundGradient (const Quantity_Color& AColor1, const Quantity_Color& AColor2, const Aspect_GradientFillMethod AType);

  void SetBackgroundGradientType (const Aspect_GradientFillMethod AType);

  //! Returns list of OpenGL Z-layers.
  const OpenGl_LayerList& LayerList() const { return myZLayers; }

  //! Returns list of openGL light sources.
  const OpenGl_ListOfLight& LightList() const { return myLights; }

  //! Returns OpenGL window implementation.
  const Handle(OpenGl_Window) GlWindow() const { return myWindow; }

  //! Returns OpenGL environment map.
  const Handle(OpenGl_Texture)& GlTextureEnv() const { return myTextureEnv; }

  //! Returns selector for BVH tree, providing a possibility to store information
  //! about current view volume and to detect which objects are overlapping it.
  OpenGl_BVHTreeSelector& BVHTreeSelector() { return myBVHSelector; }

  //! Returns true if there are immediate structures to display
  bool HasImmediateStructures() const
  {
    return myZLayers.NbImmediateStructures() != 0;
  }

protected: //! @name Internal methods for managing GL resources

  //! Initializes OpenGl resource for environment texture.
  void initTextureEnv (const Handle(OpenGl_Context)& theContext);

protected: //! @name low-level redrawing sub-routines

  //! Redraws view for the given monographic camera projection, or left/right eye.
  Standard_EXPORT virtual void redraw (const Graphic3d_Camera::Projection theProjection,
                                       OpenGl_FrameBuffer*                theReadDrawFbo);

  //! Redraws view for the given monographic camera projection, or left/right eye.
  //!
  //! Method will blit snapshot containing main scene (myMainSceneFbos or BackBuffer)
  //! into presentation buffer (myMainSceneFbos -> offscreen FBO or
  //! myMainSceneFbos -> BackBuffer or BackBuffer -> FrontBuffer),
  //! and redraw immediate structures on top.
  //!
  //! When scene caching is disabled (myTransientDrawToFront, no double buffer in window, etc.),
  //! the first step (blitting) will be skipped.
  //!
  //! @return false if immediate structures has been rendered directly into FrontBuffer
  //! and Buffer Swap should not be called.
  Standard_EXPORT virtual bool redrawImmediate (const Graphic3d_Camera::Projection theProjection,
                                                OpenGl_FrameBuffer* theReadFbo,
                                                OpenGl_FrameBuffer* theDrawFbo,
                                                const Standard_Boolean theIsPartialUpdate = Standard_False);

  //! Blit image from/to specified buffers.
  Standard_EXPORT bool blitBuffers (OpenGl_FrameBuffer*    theReadFbo,
                                    OpenGl_FrameBuffer*    theDrawFbo,
                                    const Standard_Boolean theToFlip = Standard_False);

  //! Setup default FBO.
  Standard_EXPORT void bindDefaultFbo (OpenGl_FrameBuffer* theCustomFbo = NULL);

protected: //! @name Rendering of GL graphics (with prepared drawing buffer).

  //! Renders the graphical contents of the view into the preprepared window or framebuffer.
  //! @param theProjection [in] the projection that should be used for rendering.
  //! @param theReadDrawFbo [in] the framebuffer for rendering graphics.
  //! @param theToDrawImmediate [in] the flag indicates whether the rendering performs in immediate mode.
  Standard_EXPORT virtual void render (Graphic3d_Camera::Projection theProjection,
                                       OpenGl_FrameBuffer*          theReadDrawFbo,
                                       const Standard_Boolean       theToDrawImmediate);

  //! Renders the graphical scene.
  //! @param theReadDrawFbo [in] the framebuffer for rendering graphics.
  //! @param theToDrawImmediate [in] the flag indicates whether the rendering performs in immediate mode.
  Standard_EXPORT virtual void renderScene (OpenGl_FrameBuffer*    theReadDrawFbo,
                                            const Standard_Boolean theToDrawImmediate);

  //! Draw background (gradient / image)
  Standard_EXPORT virtual void drawBackground (const Handle(OpenGl_Workspace)& theWorkspace);

  //! Render set of structures presented in the view.
  //! @param theReadDrawFbo [in] the framebuffer for rendering graphics.
  //! @param theToDrawImmediate [in] the flag indicates whether the rendering performs in immediate mode.
  Standard_EXPORT virtual void renderStructs (OpenGl_FrameBuffer*    theReadDrawFbo,
                                              const Standard_Boolean theToDrawImmediate);

  //! Renders trihedron.
  void renderTrihedron (const Handle(OpenGl_Workspace) &theWorkspace);

private:

  //! Adds the structure to display lists of the view.
  Standard_EXPORT virtual void displayStructure (const Handle(Graphic3d_CStructure)& theStructure,
                                                 const Standard_Integer thePriority) Standard_OVERRIDE;

  //! Erases the structure from display lists of the view.
  Standard_EXPORT virtual void eraseStructure (const Handle(Graphic3d_CStructure)& theStructure) Standard_OVERRIDE;

  //! Change Z layer of a structure already presented in view.
  Standard_EXPORT virtual void changeZLayer (const Handle(Graphic3d_CStructure)& theCStructure,
                                             const Graphic3d_ZLayerId theNewLayerId) Standard_OVERRIDE;

  //! Changes the priority of a structure within its Z layer in the specified view.
  Standard_EXPORT virtual void changePriority (const Handle(Graphic3d_CStructure)& theCStructure,
                                               const Standard_Integer theNewPriority) Standard_OVERRIDE;

private:

  //! Copy content of Back buffer to the Front buffer.
  void copyBackToFront();

  //! Initialize blit quad.
  OpenGl_VertexBuffer* initBlitQuad (const Standard_Boolean theToFlip);

  //! Blend together views pair into stereo image.
  void drawStereoPair();

protected:

  OpenGl_GraphicDriver*    myDriver;
  Handle(OpenGl_Window)    myWindow;
  Handle(OpenGl_Workspace) myWorkspace;
  Handle(OpenGl_Caps)      myCaps;
  Standard_Boolean&        myDeviceLostFlag;
  Standard_Boolean         myWasRedrawnGL;

  Standard_Boolean                myAntiAliasing;
  Standard_Boolean                myCulling;
  Graphic3d_TypeOfShadingModel    myShadingModel;
  Graphic3d_TypeOfSurfaceDetail   mySurfaceDetail;
  Graphic3d_TypeOfBackfacingModel myBackfacing;
  TEL_COLOUR                      myBgColor;
  OPENGL_FOG                      myFog;
  OPENGL_ZCLIP                    myZClip;
  Graphic3d_SequenceOfHClipPlane  myClipPlanes;
  Handle(Graphic3d_Camera)        myCamera;
  OpenGl_FrameBuffer*             myFBO;
  Standard_Boolean                myUseGLLight;
  Standard_Boolean                myToShowTrihedron;
  Standard_Boolean                myToShowGradTrihedron;
  TCollection_AsciiString         myBackgroundImagePath;
  Handle(Graphic3d_TextureEnv)    myTextureEnvData;
  Graphic3d_GraduatedTrihedron    myGTrihedronData;

  OpenGl_ListOfLight              myLights;
  OpenGl_LayerList                myZLayers; //!< main list of displayed structure, sorted by layers

  Graphic3d_WorldViewProjState    myWorldViewProjState; //!< camera modification state
  OpenGl_StateCounter*            myStateCounter;
  Standard_Size                   myCurrLightSourceState;

  typedef std::pair<Standard_Size, Standard_Size> StateInfo;

  StateInfo myLastOrientationState;
  StateInfo myLastViewMappingState;
  StateInfo myLastLightSourceState;

  //! Is needed for selection of overlapping objects and storage of the current view volume
  OpenGl_BVHTreeSelector myBVHSelector;

  OpenGl_Trihedron          myTrihedron;
  OpenGl_GraduatedTrihedron myGraduatedTrihedron;

  Handle(OpenGl_Texture) myTextureEnv;

protected: //! @name Rendering properties

  //! Two framebuffers (left and right views) store cached main presentation
  //! of the view (without presentation of immediate layers).
  Handle(OpenGl_FrameBuffer) myMainSceneFbos[2];
  Handle(OpenGl_FrameBuffer) myImmediateSceneFbos[2]; //!< Additional buffers for immediate layer in stereo mode.
  OpenGl_VertexBuffer        myFullScreenQuad;        //!< Vertices for full-screen quad rendering.
  OpenGl_VertexBuffer        myFullScreenQuadFlip;
  Standard_Boolean           myToFlipOutput;          //!< Flag to draw result image upside-down
  unsigned int               myFrameCounter;          //!< redraw counter, for debugging
  Standard_Boolean           myHasFboBlit;
  Standard_Boolean           myTransientDrawToFront; //!< optimization flag for immediate mode (to render directly to the front buffer)
  Standard_Boolean           myBackBufferRestored;
  Standard_Boolean           myIsImmediateDrawn;     //!< flag indicates that immediate mode buffer contains some data

protected: //! @name Background parameters

  OpenGl_AspectFace*      myTextureParams;   //!< Stores texture and its parameters for textured background
  OpenGl_BackgroundArray* myBgGradientArray; //!< Primitive array for gradient background
  OpenGl_BackgroundArray* myBgTextureArray;  //!< Primitive array for texture  background

protected: //! @name data types related to ray-tracing

  //! Result of OpenGL shaders initialization.
  enum RaytraceInitStatus
  {
    OpenGl_RT_NONE,
    OpenGl_RT_INIT,
    OpenGl_RT_FAIL
  };

  //! Describes update mode (state).
  enum RaytraceUpdateMode
  {
    OpenGl_GUM_CHECK,   //!< check geometry state
    OpenGl_GUM_PREPARE, //!< collect unchanged objects
    OpenGl_GUM_REBUILD  //!< rebuild changed and new objects
  };

  //! Defines frequently used shader variables.
  enum ShaderVariableIndex
  {
    OpenGl_RT_aPosition,

    // camera position
    OpenGl_RT_uOriginLT,
    OpenGl_RT_uOriginLB,
    OpenGl_RT_uOriginRT,
    OpenGl_RT_uOriginRB,
    OpenGl_RT_uDirectLT,
    OpenGl_RT_uDirectLB,
    OpenGl_RT_uDirectRT,
    OpenGl_RT_uDirectRB,
    OpenGl_RT_uUnviewMat,

    // 3D scene params
    OpenGl_RT_uSceneRad,
    OpenGl_RT_uSceneEps,
    OpenGl_RT_uLightAmbnt,
    OpenGl_RT_uLightCount,

    // background params
    OpenGl_RT_uBackColorTop,
    OpenGl_RT_uBackColorBot,

    // ray-tracing params
    OpenGl_RT_uShadowsEnabled,
    OpenGl_RT_uReflectEnabled,
    OpenGl_RT_uSphereMapEnabled,
    OpenGl_RT_uSphereMapForBack,
    OpenGl_RT_uTexSamplersArray,
    OpenGl_RT_uBlockedRngEnabled,

    // sampled frame params
    OpenGl_RT_uSampleWeight,
    OpenGl_RT_uFrameRndSeed,

    // adaptive FSAA params
    OpenGl_RT_uOffsetX,
    OpenGl_RT_uOffsetY,
    OpenGl_RT_uSamples,

    OpenGl_RT_NbVariables // special field
  };

  //! Defines texture samplers.
  enum ShaderSamplerNames
  {
    OpenGl_RT_SceneNodeInfoTexture  = 0,
    OpenGl_RT_SceneMinPointTexture  = 1,
    OpenGl_RT_SceneMaxPointTexture  = 2,
    OpenGl_RT_SceneTransformTexture = 3,

    OpenGl_RT_GeometryVertexTexture = 4,
    OpenGl_RT_GeometryNormalTexture = 5,
    OpenGl_RT_GeometryTexCrdTexture = 6,
    OpenGl_RT_GeometryTriangTexture = 7,

    OpenGl_RT_EnvironmentMapTexture = 8,

    OpenGl_RT_RaytraceMaterialTexture = 9,
    OpenGl_RT_RaytraceLightSrcTexture = 10,

    OpenGl_RT_FsaaInputTexture = 11,
    OpenGl_RT_PrevAccumTexture = 12,

    OpenGl_RT_OpenGlColorTexture = 13,
    OpenGl_RT_OpenGlDepthTexture = 14
  };

  //! Tool class for management of shader sources.
  class ShaderSource
  {
  public:

    //! Default shader prefix - empty string.
    static const TCollection_AsciiString EMPTY_PREFIX;

    //! Creates new uninitialized shader source.
    ShaderSource()
    {
      //
    }

  public:

    //! Returns error description in case of load fail.
    const TCollection_AsciiString& ErrorDescription() const
    {
      return myError;
    }

    //! Returns prefix to insert before the source.
    const TCollection_AsciiString& Prefix() const
    {
      return myPrefix;
    }

    //! Sets prefix to insert before the source.
    void SetPrefix (const TCollection_AsciiString& thePrefix)
    {
      myPrefix = thePrefix;
    }

    //! Returns shader source combined with prefix.
    TCollection_AsciiString Source() const;

    //! Loads shader source from specified files.
    Standard_Boolean Load (const TCollection_AsciiString* theFileNames, const TCollection_AsciiString& thePrefix = EMPTY_PREFIX);

  private:

    TCollection_AsciiString mySource; //!< Source string of the shader object
    TCollection_AsciiString myPrefix; //!< Prefix to insert before the source
    TCollection_AsciiString myError;  //!< error state

  };

  //! Default ray-tracing depth.
  static const Standard_Integer THE_DEFAULT_NB_BOUNCES = 3;

  //! Default size of traversal stack.
  static const Standard_Integer THE_DEFAULT_STACK_SIZE = 24;

  //! Compile-time ray-tracing parameters.
  struct RaytracingParams
  {
    //! Actual size of traversal stack in shader program.
    Standard_Integer StackSize;

    //! Actual ray-tracing depth (number of ray bounces).
    Standard_Integer NbBounces;

    //! Enables/disables light propagation through transparent media.
    Standard_Boolean TransparentShadows;

    //! Enables/disables global illumination (GI) effects.
    Standard_Boolean GlobalIllumination;

    //! Enables/disables the use of OpenGL bindless textures.
    Standard_Boolean UseBindlessTextures;

    //! Creates default compile-time ray-tracing parameters.
    RaytracingParams()
    : StackSize (THE_DEFAULT_STACK_SIZE),
      NbBounces (THE_DEFAULT_NB_BOUNCES),
      TransparentShadows (Standard_False),
      GlobalIllumination  (Standard_False),
      UseBindlessTextures (Standard_False)
    {
      //
    }
  };

  //! Describes state of OpenGL structure.
  struct StructState
  {
    Standard_Size StructureState;
    Standard_Size InstancedState;

    //! Creates new structure state.
    StructState (const Standard_Size theStructureState = 0,
                 const Standard_Size theInstancedState = 0)
    : StructureState (theStructureState),
      InstancedState (theInstancedState)
    {
      //
    }

    //! Creates new structure state.
    StructState (const OpenGl_Structure* theStructure)
    {
      StructureState = theStructure->ModificationState();

      InstancedState = theStructure->InstancedStructure() != NULL ?
        theStructure->InstancedStructure()->ModificationState() : 0;
    }
  };

protected: //! @name methods related to ray-tracing

  //! Updates 3D scene geometry for ray-tracing.
  Standard_Boolean updateRaytraceGeometry (const RaytraceUpdateMode      theMode,
                                           const Standard_Integer        theViewId,
                                           const Handle(OpenGl_Context)& theGlContext);

  //! Updates 3D scene light sources for ray-tracing.
  Standard_Boolean updateRaytraceLightSources (const OpenGl_Mat4& theInvModelView, const Handle(OpenGl_Context)& theGlContext);

  //! Updates environment map for ray-tracing.
  Standard_Boolean updateRaytraceEnvironmentMap (const Handle(OpenGl_Context)& theGlContext);

  //! Checks to see if the OpenGL structure is modified.
  Standard_Boolean toUpdateStructure (const OpenGl_Structure* theStructure);

  //! Adds OpenGL structure to ray-traced scene geometry.
  Standard_Boolean addRaytraceStructure (const OpenGl_Structure*       theStructure,
                                         const Handle(OpenGl_Context)& theGlContext);

  //! Adds OpenGL groups to ray-traced scene geometry.
  Standard_Boolean addRaytraceGroups (const OpenGl_Structure*        theStructure,
                                      const OpenGl_RaytraceMaterial& theStructMat,
                                      const Standard_ShortReal*      theTransform,
                                      const Handle(OpenGl_Context)&  theGlContext);

  //! Creates ray-tracing material properties.
  OpenGl_RaytraceMaterial convertMaterial (const OpenGl_AspectFace*      theAspect,
                                           const Handle(OpenGl_Context)& theGlContext);

  //! Adds OpenGL primitive array to ray-traced scene geometry.
  OpenGl_TriangleSet* addRaytracePrimitiveArray (const OpenGl_PrimitiveArray* theArray,
                                                 const Standard_Integer       theMatID,
                                                 const OpenGl_Mat4*           theTrans);

  //! Adds vertex indices from OpenGL primitive array to ray-traced scene geometry.
  Standard_Boolean addRaytraceVertexIndices (OpenGl_TriangleSet&                  theSet,
                                             const Standard_Integer               theMatID,
                                             const Standard_Integer               theCount,
                                             const Standard_Integer               theOffset,
                                             const OpenGl_PrimitiveArray&         theArray);

  //! Adds OpenGL triangle array to ray-traced scene geometry.
  Standard_Boolean addRaytraceTriangleArray (OpenGl_TriangleSet&                  theSet,
                                             const Standard_Integer               theMatID,
                                             const Standard_Integer               theCount,
                                             const Standard_Integer               theOffset,
                                             const Handle(Graphic3d_IndexBuffer)& theIndices);

  //! Adds OpenGL triangle fan array to ray-traced scene geometry.
  Standard_Boolean addRaytraceTriangleFanArray (OpenGl_TriangleSet&                  theSet,
                                                const Standard_Integer               theMatID,
                                                const Standard_Integer               theCount,
                                                const Standard_Integer               theOffset,
                                                const Handle(Graphic3d_IndexBuffer)& theIndices);

  //! Adds OpenGL triangle strip array to ray-traced scene geometry.
  Standard_Boolean addRaytraceTriangleStripArray (OpenGl_TriangleSet&                  theSet,
                                                  const Standard_Integer               theMatID,
                                                  const Standard_Integer               theCount,
                                                  const Standard_Integer               theOffset,
                                                  const Handle(Graphic3d_IndexBuffer)& theIndices);

  //! Adds OpenGL quadrangle array to ray-traced scene geometry.
  Standard_Boolean addRaytraceQuadrangleArray (OpenGl_TriangleSet&                  theSet,
                                               const Standard_Integer               theMatID,
                                               const Standard_Integer               theCount,
                                               const Standard_Integer               theOffset,
                                               const Handle(Graphic3d_IndexBuffer)& theIndices);

  //! Adds OpenGL quadrangle strip array to ray-traced scene geometry.
  Standard_Boolean addRaytraceQuadrangleStripArray (OpenGl_TriangleSet&                  theSet,
                                                    const Standard_Integer               theMatID,
                                                    const Standard_Integer               theCount,
                                                    const Standard_Integer               theOffset,
                                                    const Handle(Graphic3d_IndexBuffer)& theIndices);

  //! Adds OpenGL polygon array to ray-traced scene geometry.
  Standard_Boolean addRaytracePolygonArray (OpenGl_TriangleSet&                  theSet,
                                            const Standard_Integer               theMatID,
                                            const Standard_Integer               theCount,
                                            const Standard_Integer               theOffset,
                                            const Handle(Graphic3d_IndexBuffer)& theIndices);

  //! Uploads ray-trace data to the GPU.
  Standard_Boolean uploadRaytraceData (const Handle(OpenGl_Context)& theGlContext);

  //! Generates shader prefix based on current ray-tracing options.
  TCollection_AsciiString generateShaderPrefix (const Handle(OpenGl_Context)& theGlContext) const;

  //! Performs safe exit when shaders initialization fails.
  Standard_Boolean safeFailBack (const TCollection_ExtendedString& theMessage,
                                 const Handle(OpenGl_Context)&     theGlContext);

  //! Loads and compiles shader object from specified source.
  Handle(OpenGl_ShaderObject) initShader (const GLenum                  theType,
                                          const ShaderSource&           theSource,
                                          const Handle(OpenGl_Context)& theGlContext);

  //! Creates shader program from the given vertex and fragment shaders.
  Handle(OpenGl_ShaderProgram) initProgram (const Handle(OpenGl_Context)&      theGlContext,
                                            const Handle(OpenGl_ShaderObject)& theVertShader,
                                            const Handle(OpenGl_ShaderObject)& theFragShader);

  //! Initializes OpenGL/GLSL shader programs.
  Standard_Boolean initRaytraceResources (const Handle(OpenGl_Context)& theGlContext);

  //! Releases OpenGL/GLSL shader programs.
  void releaseRaytraceResources (const Handle(OpenGl_Context)& theGlContext);

  //! Resizes OpenGL frame buffers.
  Standard_Boolean resizeRaytraceBuffers (const Standard_Integer        theSizeX,
                                          const Standard_Integer        theSizeY,
                                          const Handle(OpenGl_Context)& theGlContext);

  //! Generates viewing rays for corners of screen quad.
  void updateCamera (const OpenGl_Mat4& theOrientation,
                     const OpenGl_Mat4& theViewMapping,
                     OpenGl_Vec3*       theOrigins,
                     OpenGl_Vec3*       theDirects,
                     OpenGl_Mat4&       theUnView);

  //! Binds ray-trace textures to corresponding texture units.
  void bindRaytraceTextures (const Handle(OpenGl_Context)& theGlContext);

  //! Unbinds ray-trace textures from corresponding texture unit.
  void unbindRaytraceTextures (const Handle(OpenGl_Context)& theGlContext);

  //! Sets uniform state for the given ray-tracing shader program.
  Standard_Boolean setUniformState (const OpenGl_Vec3*            theOrigins,
                                    const OpenGl_Vec3*            theDirects,
                                    const OpenGl_Mat4&            theUnviewMat,
                                    const Standard_Integer        theProgramId,
                                    const Handle(OpenGl_Context)& theGlContext);

  //! Runs ray-tracing shader programs.
  Standard_Boolean runRaytraceShaders (const Standard_Integer        theSizeX,
                                       const Standard_Integer        theSizeY,
                                       const OpenGl_Vec3*            theOrigins,
                                       const OpenGl_Vec3*            theDirects,
                                       const OpenGl_Mat4&            theUnviewMat,
                                       OpenGl_FrameBuffer*           theReadDrawFbo,
                                       const Handle(OpenGl_Context)& theGlContext);

  //! Redraws the window using OpenGL/GLSL ray-tracing.
  Standard_Boolean raytrace (const Standard_Integer        theSizeX,
                             const Standard_Integer        theSizeY,
                             OpenGl_FrameBuffer*           theReadDrawFbo,
                             const Handle(OpenGl_Context)& theGlContext);

protected: //! @name fields related to ray-tracing

  //! Result of shaders initialization.
  RaytraceInitStatus myRaytraceInitStatus;

  //! Is geometry data valid?
  Standard_Boolean myIsRaytraceDataValid;

  //! Warning about missing extension GL_ARB_bindless_texture has been displayed?
  Standard_Boolean myIsRaytraceWarnTextures;

  //! 3D scene geometry data for ray-tracing.
  OpenGl_RaytraceGeometry myRaytraceGeometry;

  //! Compile-time ray-tracing parameters.
  RaytracingParams myRaytraceParameters;

  //! Radius of bounding sphere of the scene.
  Standard_ShortReal myRaytraceSceneRadius;
  //! Scene epsilon to prevent self-intersections.
  Standard_ShortReal myRaytraceSceneEpsilon;

  //! OpenGL/GLSL source of ray-tracing fragment shader.
  ShaderSource myRaytraceShaderSource;
  //! OpenGL/GLSL source of adaptive-AA fragment shader.
  ShaderSource myPostFSAAShaderSource;

  //! OpenGL/GLSL ray-tracing fragment shader.
  Handle(OpenGl_ShaderObject) myRaytraceShader;
  //! OpenGL/GLSL adaptive-AA fragment shader.
  Handle(OpenGl_ShaderObject) myPostFSAAShader;

  //! OpenGL/GLSL ray-tracing shader program.
  Handle(OpenGl_ShaderProgram) myRaytraceProgram;
  //! OpenGL/GLSL adaptive-AA shader program.
  Handle(OpenGl_ShaderProgram) myPostFSAAProgram;
  //! OpenGL/GLSL program for displaying texture.
  Handle(OpenGl_ShaderProgram) myOutImageProgram;

  //! Texture buffer of data records of bottom-level BVH nodes.
  Handle(OpenGl_TextureBufferArb) mySceneNodeInfoTexture;
  //! Texture buffer of minimum points of bottom-level BVH nodes.
  Handle(OpenGl_TextureBufferArb) mySceneMinPointTexture;
  //! Texture buffer of maximum points of bottom-level BVH nodes.
  Handle(OpenGl_TextureBufferArb) mySceneMaxPointTexture;
  //! Texture buffer of transformations of high-level BVH nodes.
  Handle(OpenGl_TextureBufferArb) mySceneTransformTexture;

  //! Texture buffer of vertex coords.
  Handle(OpenGl_TextureBufferArb) myGeometryVertexTexture;
  //! Texture buffer of vertex normals.
  Handle(OpenGl_TextureBufferArb) myGeometryNormalTexture;
  //! Texture buffer of vertex UV coords.
  Handle(OpenGl_TextureBufferArb) myGeometryTexCrdTexture;
  //! Texture buffer of triangle indices.
  Handle(OpenGl_TextureBufferArb) myGeometryTriangTexture;

  //! Texture buffer of material properties.
  Handle(OpenGl_TextureBufferArb) myRaytraceMaterialTexture;
  //! Texture buffer of light source properties.
  Handle(OpenGl_TextureBufferArb) myRaytraceLightSrcTexture;

  //! 1st framebuffer (FBO) to perform adaptive FSAA.
  Handle(OpenGl_FrameBuffer) myRaytraceFBO1;
  //! 2nd framebuffer (FBO) to perform adaptive FSAA.
  Handle(OpenGl_FrameBuffer) myRaytraceFBO2;
  //! Framebuffer (FBO) for preliminary OpenGL output.
  Handle(OpenGl_FrameBuffer) myOpenGlFBO;

  //! Vertex buffer (VBO) for drawing dummy quad.
  OpenGl_VertexBuffer myRaytraceScreenQuad;

  //! Cached locations of frequently used uniform variables.
  Standard_Integer myUniformLocations[2][OpenGl_RT_NbVariables];

  //! State of OpenGL structures reflected to ray-tracing.
  std::map<const OpenGl_Structure*, StructState> myStructureStates;

  //! PrimitiveArray to TriangleSet map for scene partial update.
  std::map<Standard_Size, OpenGl_TriangleSet*> myArrayToTrianglesMap;

  //! Set of IDs of non-raytracable elements (to detect updates).
  std::set<Standard_Integer> myNonRaytraceStructureIDs;

  //! Render filter to filter out all raytracable structures.
  Handle(OpenGl_RaytraceFilter) myRaytraceFilter;

  //! Marks if environment map should be updated.
  Standard_Boolean myToUpdateEnvironmentMap;

  //! State of OpenGL layer list.
  Standard_Size myLayerListState;

  //! Number of accumulated frames (for progressive rendering).
  Standard_Integer myAccumFrames;

  //! Stored ray origins used for detection of camera movements.
  OpenGl_Vec3 myPreviousOrigins[3];

  //! Bullard RNG to produce random sequence.
  math_BullardGenerator myRNG;

public:

  DEFINE_STANDARD_ALLOC
  DEFINE_STANDARD_RTTI(OpenGl_View, Graphic3d_CView) // Type definition

  friend class OpenGl_GraphicDriver;
  friend class OpenGl_Workspace;
};

#endif // _OpenGl_View_Header