/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org

Copyright (c) 2000-2011 Torus Knot Software Ltd
Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
-----------------------------------------------------------------------------
*/
#ifndef _ShaderFFPFog_
#define _ShaderFFPFog_

#include "OgreShaderPrerequisites.h"
#ifdef RTSHADER_SYSTEM_BUILD_CORE_SHADERS
#include "OgreShaderParameter.h"
#include "OgreShaderSubRenderState.h"
#include "OgreVector4.h"

namespace Ogre {
namespace RTShader {

/** \addtogroup Core
*  @{
*/
/** \addtogroup RTShader
*  @{
*/

/** Fog sub render state implementation of the Fixed Function Pipeline.
@see http://msdn.microsoft.com/en-us/library/ee418582.aspx
Derives from SubRenderState class.
*/
class _OgreRTSSExport FFPFog : public SubRenderState
{
public:

	// Fog calculation mode enum.
	enum CalcMode
	{
		CM_PER_VERTEX	= 1,		// Per vertex fog calculations. (Default).
		CM_PER_PIXEL	= 2			// Per pixel fog calculations.
	};

// Interface.
public:

	/** Class default constructor */
	FFPFog();

	/** 
	@see SubRenderState::getType.
	*/
	virtual const String&	getType					() const;

	/** 
	@see SubRenderState::getType.
	*/
	virtual int				getExecutionOrder		() const;

	/** 
	@see SubRenderState::updateGpuProgramsParams.
	*/
	virtual void			updateGpuProgramsParams	(Renderable* rend, Pass* pass, const AutoParamDataSource* source, const LightList* pLightList);

	/** 
	@see SubRenderState::copyFrom.
	*/
	virtual void			copyFrom				(const SubRenderState& rhs);

	/** 
	@see SubRenderState::preAddToRenderState.
	*/
	virtual bool			preAddToRenderState		(RenderState* renderState, Pass* srcPass, Pass* dstPass);

	/** 
	Set the fog properties this fog sub render state should emulate.
	@param fogMode The fog mode to emulate (FOG_NONE, FOG_EXP, FOG_EXP2, FOG_LINEAR).
	@param fogColour The colour of the fog.
	@param fogStart Start distance of fog, used for linear mode only.
	@param fogEnd End distance of fog, used for linear mode only.
	@param fogDensity Fog density used in exponential modes only.
	@see http://msdn.microsoft.com/en-us/library/ee418606.aspx
	*/
	void			setFogProperties				(FogMode fogMode, 
		const ColourValue& fogColour, 
		float fogStart, 
		float fogEnd, 
		float fogDensity);

	/** 
	Set the fog calculation mode. Either per vertex or per pixel.
	@param calcMode The calculation mode to set.
	*/
	void			setCalcMode						(CalcMode calcMode) { mCalcMode = calcMode; }

	/** 
	Return the current calculation mode.
	*/
	CalcMode		getCalcMode						() const { return mCalcMode; }

	static String Type;

// Protected methods
protected:

	/** 
	@see SubRenderState::resolveParameters.
	*/
	virtual bool			resolveParameters		(ProgramSet* programSet);

	/** 
	@see SubRenderState::resolveDependencies.
	*/
	virtual bool			resolveDependencies		(ProgramSet* programSet);

	/** 
	@see SubRenderState::addFunctionInvocations.
	*/
	virtual bool			addFunctionInvocations	(ProgramSet* programSet);

// Attributes.
protected:	
	CalcMode			mCalcMode;				// Fog calculation mode.
	FogMode				mFogMode;				// Fog formula. 
	ColourValue			mFogColourValue;		// Fog colour value.
	Vector4				mFogParamsValue;		// Fog parameters (density, start, end, 1/end-start).
	bool				mPassOverrideParams;	// True if the fog parameters should be taken from the pass.

	UniformParameterPtr	mWorldViewProjMatrix;	// World view projection parameter.		
	UniformParameterPtr	mFogColour;				// Fog colour parameter.	
	UniformParameterPtr	mFogParams;				// Fog parameters program parameter.	
	ParameterPtr		mVSInPos;				// Vertex shader input position parameter.
	ParameterPtr		mVSOutFogFactor;		// Vertex shader output fog colour parameter.
	ParameterPtr		mPSInFogFactor;			// Pixel shader input fog factor.
	ParameterPtr		mVSOutDepth;			// Vertex shader output depth.
	ParameterPtr		mPSInDepth;				// Pixel shader input depth.
	ParameterPtr		mPSOutDiffuse;			// Pixel shader output diffuse colour.
};


/** 
A factory that enables creation of FFPFog instances.
@remarks Sub class of SubRenderStateFactory
*/
class _OgreRTSSExport FFPFogFactory : public SubRenderStateFactory
{
public:

	/** 
	@see SubRenderStateFactory::getType.
	*/
	virtual const String&	getType				() const;

	/** 
	@see SubRenderStateFactory::createInstance.
	*/
	virtual SubRenderState*	createInstance		(ScriptCompiler* compiler, PropertyAbstractNode* prop, Pass* pass);

	/** 
	@see SubRenderStateFactory::writeInstance.
	*/
	virtual void			writeInstance		(MaterialSerializer* ser, SubRenderState* subRenderState, Pass* srcPass, Pass* dstPass);

	
protected:

	/** 
	@see SubRenderStateFactory::createInstanceImpl.
	*/
	virtual SubRenderState*	createInstanceImpl	();


};

/** @} */
/** @} */

}
}

#endif
#endif

