NormalManager.hpp

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//  This file is part of ff3d - http://www.freefem.org/ff3d
//  Copyright (C) 2005 Stephane Del Pino
//
//  This program is free software; you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation; either version 2, or (at your option)
//  any later version.
//
//  This program 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 General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program; if not, write to the Free Software Foundation,
//  Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
//  $Id: NormalManager.hpp,v 1.5 2007/08/02 23:11:54 delpinux Exp $

#ifndef NORMAL_MANAGER_HPP
#define NORMAL_MANAGER_HPP

#include <ThreadStaticBase.hpp>

#include <SurfElem.hpp>
#include <ReferenceCounting.hpp>

class NormalManager
  : public ThreadStaticBase<NormalManager>
{
private:
  const SurfElem* __surfElem;   
  size_t __counter;             
  mutable ReferenceCounting<TinyVector<3, real_t> >
  __normal;                     
  void __buildNormal() const
  {
    if (__surfElem == 0) {
      throw ErrorHandler(__FILE__,__LINE__,
                         "Cannot evaluate normal, no surface is defined",
                         ErrorHandler::unexpected);
    }
    if (__normal == 0) {
      __normal = new TinyVector<3, real_t>(__surfElem->normal());
    }
  }

public:
  void subscribe(const SurfElem* s)
  {
    __counter++;
    __surfElem = s;
  }

  void update(const SurfElem* s)
  {
    ASSERT(__surfElem != 0);
    __surfElem = s;
    __normal = 0; // normal is to recompute
  }

  void unsubscribe()
  {
    ASSERT(__counter != 0);
    __counter--;
    if (__counter == 0) {
      __surfElem = 0;
      __normal = 0;
    }
  }
  
  real_t nx() const
  {
    __buildNormal();
    return (*__normal)[0];
  }

  real_t ny() const
  {
    __buildNormal();
    return (*__normal)[1];
  }

  real_t nz() const
  {
    __buildNormal();
    return (*__normal)[2];
  }

  explicit NormalManager()
    : __surfElem(0),
      __counter(0),
      __normal(0)
  {
    ;
  }

  ~NormalManager()
  {
    ASSERT(__counter  == 0);
    ASSERT(__surfElem == 0);
    ASSERT(__normal   == 0);
  }
};

#endif // NORMAL_MANAGER_HPP

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