#ifndef __SurfaceTension_He2014_h__
#define __SurfaceTension_He2014_h__

#include "SPlisHSPlasH/Common.h"
#include "SPlisHSPlasH/FluidModel.h"
#include "SPlisHSPlasH/NonPressureForceBase.h"

namespace SPH
{
	/** \brief This class implements the surface tension method introduced
	* by He et al. [HWZ+14].
	*
	* References:
	* - [HWZ+14] Xiaowei He, Huamin Wang, Fengjun Zhang, Hongan Wang, Guoping Wang, and Kun Zhou. Robust simulation of sparsely sampled thin features in SPH-based free surface flows. ACM Trans. Graph., 34(1):7:1-7:9, December 2014. URL: http://doi.acm.org/10.1145/2682630
	*/
	class SurfaceTension_He2014 : public NonPressureForceBase
	{
	protected: 
		Real m_surfaceTension;
		Real m_surfaceTensionBoundary;

		std::vector<Real> m_color;
		std::vector<Real> m_gradC2;

		virtual void initParameters();

	public:
		static std::string METHOD_NAME;
		static int SURFACE_TENSION;
		static int SURFACE_TENSION_BOUNDARY;

		SurfaceTension_He2014(FluidModel *model);
		virtual ~SurfaceTension_He2014(void);

		static NonPressureForceBase* creator(FluidModel* model) { return new SurfaceTension_He2014(model); }
		virtual std::string getMethodName() { return METHOD_NAME; }

		virtual void step();
		virtual void reset();

		virtual void performNeighborhoodSearchSort();

		FORCE_INLINE const Real getColor(const unsigned int i) const
		{
			return m_color[i];
		}

		FORCE_INLINE Real& getColor(const unsigned int i)
		{
			return m_color[i];
		}

		FORCE_INLINE void setColor(const unsigned int i, const Real p)
		{
			m_color[i] = p;
		}

		FORCE_INLINE const Real getGradC2(const unsigned int i) const
		{
			return m_gradC2[i];
		}

		FORCE_INLINE Real& getGradC2(const unsigned int i)
		{
			return m_gradC2[i];
		}

		FORCE_INLINE void setGradC2(const unsigned int i, const Real p)
		{
			m_gradC2[i] = p;
		}
	};
}

#endif