/*
--------------------------------------------------------------------------------
This source file is part of SkyX.
Visit ---

Copyright (C) 2009 Xavier Verguín González <xavierverguin@hotmail.com>
                                           <xavyiy@gmail.com>

This program 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 2 of the License, 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 Lesser General Public License for more details.

You should have received a copy of the GNU Lesser 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, or go to
http://www.gnu.org/copyleft/lesser.txt.
--------------------------------------------------------------------------------
*/

#ifndef _SkyX_AtmosphereManager_H_
#define _SkyX_AtmosphereManager_H_

#include "SkyxPrerequisites.h"

namespace SkyX
{

	/*!
	*/
  class SkyXDllExport AtmosphereManager 
	{
	public:
		/*!
		Atmosphere options 
		 */
		struct Options 
		{
			Ogre::Real InnerRadius;			//!< Inner atmosphere radius
			Ogre::Real OuterRadius;			//!< Outer atmosphere radius
			Ogre::Real HeightPosition;  //!< Height position, in [0, 1] range, 0=InnerRadius, 1=OuterRadius
			Ogre::Real RayleighMultiplier;	//!< Rayleigh multiplier
			Ogre::Real MieMultiplier;	  //!< Mie multiplier
			Ogre::Real SunIntensity;	  //!< Sun intensity
			Ogre::Vector3 WaveLength;	  //!< WaveLength for RGB channels
			Ogre::Real G;					      //!< Phase function
			Ogre::Real Exposure;			  //!< Exposure coeficient
			int NumberOfSamples;			  //!< Number of samples

			/*!
			Default constructor
			*/
			Options()
			{
			  InnerRadius = 9.77501f;
				OuterRadius = 10.2963f;
				HeightPosition = 0.01f;
				RayleighMultiplier = 0.0022f;
				MieMultiplier = 0.000675f;
				SunIntensity = 30;
				WaveLength = Ogre::Vector3(0.57f, 0.54f, 0.44f);
				G = -0.991;
				Exposure = 2.0f;
				NumberOfSamples = 4;
			}

			/*!
			Constructor
      @param _InnerRadius Inner atmosphere radius
			@param _OuterRadius Outer atmosphere radius
			@param _HeightPosition Height position, in [0, 1] range, 0=InnerRadius, 1=OuterRadius
			@param _RayleighMultiplier Rayleigh multiplier
			@param _MieMultiplier Mie multiplier
			@param _SunIntensity Sun intensity
			@param _WaveLength Wave length for RGB channels
			@param _G Phase function
			@param _Exposure Exposure
			@param _NumerOfSamples Number of samples
			*/
			Options(const Ogre::Real& _InnerRadius, const Ogre::Real& _OuterRadius,
              const Ogre::Real& _HeightPosition,
              const Ogre::Real& _RayleighMultiplier, const Ogre::Real& _MieMultiplier, const Ogre::Real& _SunIntensity,
              const Ogre::Vector3& _WaveLength, const Ogre::Real& _G, const Ogre::Real& _Exposure, const int& _NumerOfSamples)
			{
        InnerRadius = _InnerRadius;
        OuterRadius = _OuterRadius;
        HeightPosition = _HeightPosition;
        RayleighMultiplier = _RayleighMultiplier;
        MieMultiplier = _MieMultiplier;
        SunIntensity = _SunIntensity;
        WaveLength = _WaveLength;
        G = _G;
        Exposure = _Exposure;
        NumberOfSamples = _NumerOfSamples;
			}
		};
	protected:
	private:
		Options mOptions;	//!< Our options
		SkyX* mSkyX;		  //!< SkyX parent pointer

	public:
	    /*!
		Constructor
		@param s Parent SkyX pointer
		*/
		AtmosphereManager(SkyX* s);

		/*!
		Destructor 
		*/
		~AtmosphereManager();

		/*!
		Set options
		@param _Options New options
		*/
		inline void setOptions(const Options& _Options)
		{
			_update(0.0f, _Options);
		}

		/*!
		Get current options 
		@return Current options
		*/
		inline const Options& getOptions() const
		{
			return mOptions;
		}

		/*!
		Update atmoshpere
    @param Ogre::Real& advanceTime (in seconds)
		@param NewOptions Update only the differences between actual parameters and new ones.
		@param ForceToUpdateAll Forces to upload all current parameters to skyx material.
		@remarks Current options parameters are updated if needed.
		*/
    void _update(const Ogre::Real& advanceTime, const Options& NewOptions, const bool& ForceToUpdateAll = false);
	protected:
	private:
		/*!
		Shader scale funtion 
		@param cos Cos
		@param uScaleDepth Scale Depth
		@return Scale
		*/
		const float _scale(const float& cos, const float& uScaleDepth) const;
	};

}

#endif