// 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_ShadowMap_HeaderFile
#define _OpenGl_ShadowMap_HeaderFile

#include <Graphic3d_Mat4.hxx>
#include <NCollection_Array1.hxx>
#include <NCollection_Shared.hxx>
#include <OpenGl_NamedResource.hxx>

class gp_XYZ;
class Graphic3d_Camera;
class Graphic3d_CLight;
class Graphic3d_CView;
class OpenGl_FrameBuffer;
class OpenGl_Texture;

//! This class contains shadow mapping resources.
class OpenGl_ShadowMap : public OpenGl_NamedResource
{
  DEFINE_STANDARD_RTTIEXT(OpenGl_ShadowMap, OpenGl_NamedResource)
public:

  //! Empty constructor.
  OpenGl_ShadowMap();

  //! Releases all OpenGL resources.
  Standard_EXPORT virtual void Release (OpenGl_Context* theCtx) Standard_OVERRIDE;

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

  //! Destructor.
  Standard_EXPORT virtual ~OpenGl_ShadowMap();

  //! Return TRUE if defined.
  Standard_EXPORT bool IsValid() const;

  //! Return framebuffer.
  const Handle(OpenGl_FrameBuffer)& FrameBuffer() const { return myShadowMapFbo; }

  //! Return depth texture.
  Standard_EXPORT const Handle(OpenGl_Texture)& Texture() const;

  //! Return light source casting the shadow or NULL if undefined.
  const Handle(Graphic3d_CLight)& LightSource() const { return myShadowLight; }

  //! Set light source casting the shadow.
  void SetLightSource (const Handle(Graphic3d_CLight)& theLight) { myShadowLight = theLight; }

  //! Return rendering camera.
  const Handle(Graphic3d_Camera)& Camera() const { return myShadowCamera; }

  //! Return light source mapping matrix.
  const Graphic3d_Mat4& LightSourceMatrix() const { return myLightMatrix; }

  //! Set light source mapping matrix.
  void SetLightSourceMatrix (const Graphic3d_Mat4& theMat) { myLightMatrix = theMat; }

  //! Returns shadowmap bias.
  Standard_ShortReal ShadowMapBias() const { return myShadowMapBias; }

  //! Sets shadowmap bias.
  void SetShadowMapBias (Standard_ShortReal theBias) { myShadowMapBias = theBias; }

  //! Compute camera.
  //! @param theView   [in] active view
  //! @param theOrigin [in] when not-NULL - displace shadow map camera to specified Z-Layer origin
  Standard_EXPORT bool UpdateCamera (const Graphic3d_CView& theView,
                                     const gp_XYZ* theOrigin = NULL);

private:

  Handle(OpenGl_FrameBuffer) myShadowMapFbo;  //!< frame buffer for rendering shadow map
  Handle(Graphic3d_CLight)   myShadowLight;   //!< light source to render shadow map
  Handle(Graphic3d_Camera)   myShadowCamera;  //!< rendering camera
  Graphic3d_Mat4             myLightMatrix;   //!< light source matrix
  Standard_ShortReal         myShadowMapBias; //!< shadowmap bias

};

//! Array of shadow maps.
class OpenGl_ShadowMapArray : public Standard_Transient, public NCollection_Array1<Handle(OpenGl_ShadowMap)>
{
public:
  //! Empty constructor.
  OpenGl_ShadowMapArray() {}

  //! Releases all OpenGL resources.
  Standard_EXPORT void Release (OpenGl_Context* theCtx);

  //! Return TRUE if defined.
  bool IsValid() const
  {
    return !IsEmpty()
         && First()->IsValid();
  }

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

public:
  DEFINE_STANDARD_ALLOC
  DEFINE_NCOLLECTION_ALLOC

};

#endif // _OpenGl_ShadowMap_HeaderFile