// Created on: 2021-01-15
// Copyright (c) 2021 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_DepthPeeling_HeaderFile
#define _OpenGl_DepthPeeling_HeaderFile

#include "OpenGl_FrameBuffer.hxx"
#include "OpenGl_NamedResource.hxx"

//! Class provides FBOs for dual depth peeling.
class OpenGl_DepthPeeling : public OpenGl_NamedResource
{
  DEFINE_STANDARD_RTTIEXT(OpenGl_DepthPeeling, OpenGl_NamedResource)
public:
  //! Constructor.
  Standard_EXPORT OpenGl_DepthPeeling();

  //! Destructor.
  Standard_EXPORT ~OpenGl_DepthPeeling() override;

  //! Release OpenGL resources
  Standard_EXPORT void Release(OpenGl_Context* theGlCtx) override;

  //! Returns estimated GPU memory usage for holding data without considering overheads and
  //! allocation alignment rules.
  Standard_EXPORT size_t EstimatedDataSize() const override;

  //! Attach a texture image.
  //! Resets the active FBO to 0.
  Standard_EXPORT void AttachDepthTexture(
    const occ::handle<OpenGl_Context>& theCtx,
    const occ::handle<OpenGl_Texture>& theDepthStencilTexture);

  //! Detach a texture image.
  //! Resets the active FBO to 0.
  Standard_EXPORT void DetachDepthTexture(const occ::handle<OpenGl_Context>& theCtx);

  //! Returns additional buffers for ping-pong
  const occ::handle<OpenGl_FrameBuffer>* DepthPeelFbosOit() const { return myDepthPeelFbosOit; }

  //! Returns additional buffers for ping-pong
  const occ::handle<OpenGl_FrameBuffer>* FrontBackColorFbosOit() const
  {
    return myFrontBackColorFbosOit;
  }

  //! Returns additional FBO for depth peeling
  const occ::handle<OpenGl_FrameBuffer>& BlendBackFboOit() const { return myBlendBackFboOit; }

private:
  occ::handle<OpenGl_FrameBuffer> myDepthPeelFbosOit[2];      //!< depth + front color + back color
  occ::handle<OpenGl_FrameBuffer> myFrontBackColorFbosOit[2]; //!< front color + back color
  occ::handle<OpenGl_FrameBuffer> myBlendBackFboOit;
};

#endif // _OpenGl_DepthPeeling_HeaderFile