// Created on: 2014-09-30
// Created by: Denis BOGOLEPOV
// Copyright (c) 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_MatrixState_H__
#define _OpenGl_MatrixState_H__

#include <OpenGl_Vec.hxx>
#include <NCollection_Vector.hxx>

//! Software implementation for OpenGL matrix stack.
template<class T>
class OpenGl_MatrixState
{
public:

  //! Constructs matrix state object.
  OpenGl_MatrixState()
  : myStack (8),
    myStackHead (-1)
  {
    //
  }

  //! Pushes current matrix into stack.
  void Push()
  {
    if (++myStackHead >= myStack.Size())
    {
      myStack.Append (myCurrent);
    }
    else
    {
      myStack.SetValue (myStackHead, myCurrent);
    }
  }

  //! Pops matrix from stack to current.
  void Pop()
  {
    Standard_ASSERT_RETURN (myStackHead != -1, "Matrix stack already empty when MatrixState.Pop() called.", );
    myCurrent = myStack.Value (myStackHead--);
  }

  //! @return current matrix.
  const typename OpenGl::MatrixType<T>::Mat4& Current()
  {
    return myCurrent;
  }

  //! Sets given matrix as current.
  void SetCurrent (const typename OpenGl::MatrixType<T>::Mat4& theNewCurrent)
  {
    myCurrent = theNewCurrent;
  }

  //! Change current matrix.
  typename OpenGl::MatrixType<T>::Mat4& ChangeCurrent()
  {
    return myCurrent;
  }

  //! Sets given matrix as current.
  template <typename Other_t>
  void SetCurrent (const typename OpenGl::MatrixType<Other_t>::Mat4& theNewCurrent)
  {
    myCurrent.Convert (theNewCurrent);
  }

  //! Sets current matrix to identity.
  void SetIdentity()
  {
    myCurrent = typename OpenGl::MatrixType<T>::Mat4();
  }

private:

  NCollection_Vector<typename OpenGl::MatrixType<T>::Mat4> myStack;     //!< Collection used to maintenance matrix stack
  typename OpenGl::MatrixType<T>::Mat4                     myCurrent;   //!< Current matrix
  Standard_Integer                                         myStackHead; //!< Index of stack head
};

#endif // _OpenGl_MatrixState_H__