/*===========================================================================*\
*                                                                            *
*                              OpenFlipper                                   *
*      Copyright (C) 2001-2011 by Computer Graphics Group, RWTH Aachen       *
*                           www.openflipper.org                              *
*                                                                            *
*--------------------------------------------------------------------------- *
*  This file is part of OpenFlipper.                                         *
*                                                                            *
*  OpenFlipper is free software: you can redistribute it and/or modify       *
*  it under the terms of the GNU Lesser General Public License as            *
*  published by the Free Software Foundation, either version 3 of            *
*  the License, or (at your option) any later version with the               *
*  following exceptions:                                                     *
*                                                                            *
*  If other files instantiate templates or use macros                        *
*  or inline functions from this file, or you compile this file and          *
*  link it with other files to produce an executable, this file does         *
*  not by itself cause the resulting executable to be covered by the         *
*  GNU Lesser General Public License. This exception does not however        *
*  invalidate any other reasons why the executable file might be             *
*  covered by the GNU Lesser General Public License.                         *
*                                                                            *
*  OpenFlipper is distributed in the hope that it will be useful,            *
*  but WITHOUT ANY WARRANTY; without even the implied warranty of            *
*  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             *
*  GNU Lesser General Public License for more details.                       *
*                                                                            *
*  You should have received a copy of the GNU LesserGeneral Public           *
*  License along with OpenFlipper. If not,                                   *
*  see <http://www.gnu.org/licenses/>.                                       *
*                                                                            *
\*===========================================================================*/



#pragma once


#include <QObject>

#include <OpenFlipper/BasePlugin/BaseInterface.hh>
#include <OpenFlipper/BasePlugin/RenderInterface.hh>
#include <OpenFlipper/BasePlugin/LoggingInterface.hh>


#include <ACG/GL/IRenderer.hh>

class DepthPeeling : public QObject, BaseInterface, RenderInterface, LoggingInterface, ACG::IRenderer
{
  Q_OBJECT
    Q_INTERFACES(BaseInterface)
    Q_INTERFACES(RenderInterface)
    Q_INTERFACES(LoggingInterface)

signals:
  // LoggingInterface
  void log(Logtype _type, QString _message);
  void log(QString _message);


public:
  DepthPeeling();
  ~DepthPeeling();

  QString name() { return (QString("DepthPeeling Plugin")); };
  QString description( ) { return (QString(tr("DepthPeeling Rendering Pipeline (Alpha Version!)"))); };


  /// overide addRenderObject function to include OIT check
  void addRenderObject(ACG::RenderObject* _renderObject);


public slots:
  QString version() { return QString("1.0"); };

  QString renderObjectsInfo(bool _outputShaderInfo) { return dumpCurrentRenderObjectsToString(&sortedObjects_[0],_outputShaderInfo); };


private slots:

  //BaseInterface
  void initializePlugin();
  void exit(){}

  // RenderInterface
  void render(ACG::GLState* _glState, Viewer::ViewerProperties& _properties);
  QString rendererName() {return QString("Alpha_Version_DepthPeeling");}
  void supportedDrawModes(ACG::SceneGraph::DrawModes::DrawMode& _mode) {_mode = ACG::SceneGraph::DrawModes::DEFAULT;}

  QString checkOpenGL();



private:


  /// peel the scene from front to back, one layer per pass
  void renderFrontPeeling(ACG::GLState* _glState, Viewer::ViewerProperties& _properties);

  /// peel the scene with dual depth peeling, two layers per pass
  void renderDualPeeling(ACG::GLState* _glState, Viewer::ViewerProperties& _properties);



  /// draw a projected quad in [-1, -1] - [1, 1] range
  void drawProjQuad(GLSL::Program* _prog);

  /// vbo containing a quad in projection space
  GLuint screenQuadVBO_;
  ACG::VertexDeclaration* screenQuadDecl_;


  // single layer depth peeling
  struct PeelLayer
  {
    /// target framebuffer for colorTex and depthBuf
    GLuint fbo;

    /// color rendertarget
    GLuint colorTex;
    /// hardware depth buffer
    GLuint depthBuf;
    /// depth-buffer rendertarget
    GLuint depthTex; // encountered gpu-model specific problems when reading from depthBuf directly
  };

  /// blends one depth-layer into the current scene target
  GLSL::Program* peelBlend_;

  /// final copy into back-buffer
  GLSL::Program* peelFinal_;

  /** 
  Copy depth-texture of first layer into hardware z-buffer.
  This is needed for post-processing or renderobjects with low priority.
  */
  GLSL::Program* peelDepthCopy_;

  /// occlusion query determining end of peeling (last layer)
  GLuint peelQueryID_;


  /// dual depth peeling shaders
  GLSL::Program* peelBlendDual_;
  GLSL::Program* peelFinalDual_;


  /// Collection of framebuffers for each viewport
  struct ViewerResources
  {
    ViewerResources();

    /// viewer window width
    unsigned int glWidth_;

    /// viewer window height
    unsigned int glHeight_;


    // depth peeling textures

    /// ping pong between two consecutive layers
    PeelLayer peelTargets_[2];

    GLuint peelBlendTex_;
    GLuint peelBlendFbo_;



    // dual depth peeling textures
    //  ping-pong buffer for (depth, front, back) targets
    GLuint dualDepthTex_[2]; // float2: (-minDepth, maxDepth)
    GLuint dualFrontTex_[2]; // rgba: color of front-peeled layer
    GLuint dualBackTex_[2];  // rgba: color of back-peeled layer
    GLuint dualBlendTex_;    // rgb:  color accumulation buffer
    GLuint dualFbo_; // targets: {depth0, front0, back0,  depth1, front1, back1,  blend}
  };

  /// Allocate framebuffers and load shaders for depth-peeling.
  void initDepthPeeling();

  /// Allocate framebuffers and load shaders for dual-depth-peeling.
  void initDualDepthPeeling();

  /// Change viewport size for allocated rendertargets.
  void updateViewerResources(bool _dualPeeling, int _viewerId, unsigned int _newWidth, unsigned int _newHeight);

  /**
  * Stores framebuffer resources for each viewport.
  * Mapping: viewerID -> ViewerResources
  */
  std::map<int, ViewerResources> viewerRes_;




  // debug functions
//   GLSL::Program* dbgProg_;
// 
//   void dbgDrawTex(GLuint _texID);
};