SPHSolver2.h

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/*************************************************************************
> File Name: SPHSolver2.h
> Project Name: CubbyFlow
> Author: Chan-Ho Chris Ohk
> Purpose: 2-D SPH solver.
> Created Time: 2017/06/03
> Copyright (c) 2018, Chan-Ho Chris Ohk
*************************************************************************/
#ifndef CUBBYFLOW_SPH_SOLVER2_H
#define CUBBYFLOW_SPH_SOLVER2_H

#include <Core/Solver/Particle/ParticleSystemSolver2.h>
#include <Core/SPH/SPHSystemData2.h>

namespace CubbyFlow
{
    class SPHSolver2 : public ParticleSystemSolver2
    {
    public:
        class Builder;

        SPHSolver2();

        virtual ~SPHSolver2();

        SPHSolver2(double targetDensity, double targetSpacing, double relativeKernelRadius);

        double GetEosExponent() const;

        void SetEosExponent(double newEosExponent);

        double GetNegativePressureScale() const;

        void SetNegativePressureScale(double newNegativePressureScale);

        double GetViscosityCoefficient() const;

        void SetViscosityCoefficient(double newViscosityCoefficient);

        double GetPseudoViscosityCoefficient() const;

        void SetPseudoViscosityCoefficient(double newPseudoViscosityCoefficient);

        double GetSpeedOfSound() const;

        void SetSpeedOfSound(double newSpeedOfSound);

        double GetTimeStepLimitScale() const;

        void SetTimeStepLimitScale(double newScale);

        SPHSystemData2Ptr GetSPHSystemData() const;

        static Builder GetBuilder();

    protected:
        unsigned int GetNumberOfSubTimeSteps(double timeIntervalInSeconds) const override;

        void AccumulateForces(double timeStepInSeconds) override;

        void OnBeginAdvanceTimeStep(double timeStepInSeconds) override;

        void OnEndAdvanceTimeStep(double timeStepInSeconds) override;

        virtual void AccumulateNonPressureForces(double timeStepInSeconds);

        virtual void AccumulatePressureForce(double timeStepInSeconds);

        void ComputePressure();

        void AccumulatePressureForce(
            const ConstArrayAccessor1<Vector2D>& positions,
            const ConstArrayAccessor1<double>& densities,
            const ConstArrayAccessor1<double>& pressures,
            ArrayAccessor1<Vector2D> pressureForces);

        void AccumulateViscosityForce();

        void ComputePseudoViscosity(double timeStepInSeconds);

    private:
        double m_eosExponent = 7.0;

        double m_negativePressureScale = 0.0;

        double m_viscosityCoefficient = 0.01;

        double m_pseudoViscosityCoefficient = 10.0;

        double m_speedOfSound = 100.0;

        double m_timeStepLimitScale = 1.0;
    };

    using SPHSolver2Ptr = std::shared_ptr<SPHSolver2>;
    
    template <typename DerivedBuilder>
    class SPHSolverBuilderBase2
    {
    public:
        DerivedBuilder& WithTargetDensity(double targetDensity);

        DerivedBuilder& WithTargetSpacing(double targetSpacing);

        DerivedBuilder& WithRelativeKernelRadius(double relativeKernelRadius);

    protected:
        double m_targetDensity = WATER_DENSITY;
        double m_targetSpacing = 0.1;
        double m_relativeKernelRadius = 1.8;
    };

    template <typename T>
    T& SPHSolverBuilderBase2<T>::WithTargetDensity(double targetDensity)
    {
        m_targetDensity = targetDensity;
        return static_cast<T&>(*this);
    }

    template <typename T>
    T& SPHSolverBuilderBase2<T>::WithTargetSpacing(double targetSpacing)
    {
        m_targetSpacing = targetSpacing;
        return static_cast<T&>(*this);
    }

    template <typename T>
    T& SPHSolverBuilderBase2<T>::WithRelativeKernelRadius(double relativeKernelRadius)
    {
        m_relativeKernelRadius = relativeKernelRadius;
        return static_cast<T&>(*this);
    }

    class SPHSolver2::Builder final : public SPHSolverBuilderBase2<SPHSolver2::Builder>
    {
    public:
        SPHSolver2 Build() const;

        SPHSolver2Ptr MakeShared() const;
    };
}

#endif