GridFluidSolver2.h

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/*************************************************************************
> File Name: GridFluidSolver2.h
> Project Name: CubbyFlow
> Author: Dongmin Kim
> Purpose: Abstract base class for grid-based 2-D fluid solver.
> Created Time: 2017/08/10
> Copyright (c) 2018, Dongmin Kim
*************************************************************************/
#ifndef CUBBYFLOW_GRID_FLUID_SOLVER2_H
#define CUBBYFLOW_GRID_FLUID_SOLVER2_H

#include <Core/Animation/PhysicsAnimation.h>
#include <Core/Collider/Collider2.h>
#include <Core/Emitter/GridEmitter2.h>
#include <Core/Grid/GridSystemData2.h>
#include <Core/Solver/Advection/AdvectionSolver2.h>
#include <Core/Solver/Grid/GridDiffusionSolver2.h>
#include <Core/Solver/Grid/GridPressureSolver2.h>

namespace CubbyFlow
{
    class GridFluidSolver2 : public PhysicsAnimation
    {
    public:
        class Builder;

        GridFluidSolver2();

        GridFluidSolver2(
            const Size2& resolution,
            const Vector2D& gridSpacing,
            const Vector2D& gridOrigin);

        virtual ~GridFluidSolver2();

        const Vector2D& GetGravity() const;

        void SetGravity(const Vector2D& newGravity);

        double GetViscosityCoefficient() const;

        void SetViscosityCoefficient(double newValue);

        double GetCFL(double timeIntervalInSeconds) const;

        double GetMaxCFL() const;

        void SetMaxCFL(double newCFL);

        bool GetUseCompressedLinearSystem() const;
        
        void SetUseCompressedLinearSystem(bool onoff);

        const AdvectionSolver2Ptr& GetAdvectionSolver() const;

        void SetAdvectionSolver(const AdvectionSolver2Ptr& newSolver);

        const GridDiffusionSolver2Ptr& GetDiffusionSolver() const;

        void SetDiffusionSolver(const GridDiffusionSolver2Ptr& newSolver);

        const GridPressureSolver2Ptr& GetPressureSolver() const;

        void SetPressureSolver(const GridPressureSolver2Ptr& newSolver);

        int GetClosedDomainBoundaryFlag() const;

        void SetClosedDomainBoundaryFlag(int flag);

        const GridSystemData2Ptr& GetGridSystemData() const;

        void ResizeGrid(
            const Size2& newSize,
            const Vector2D& newGridSpacing,
            const Vector2D& newGridOrigin) const;

        Size2 GetResolution() const;

        Vector2D GetGridSpacing() const;

        Vector2D GetGridOrigin() const;

        const FaceCenteredGrid2Ptr& GetVelocity() const;

        const Collider2Ptr& GetCollider() const;

        void SetCollider(const Collider2Ptr& newCollider);

        const GridEmitter2Ptr& GetEmitter() const;

        void SetEmitter(const GridEmitter2Ptr& newEmitter);

        static Builder GetBuilder();

    protected:
        void OnInitialize() override;

        void OnAdvanceTimeStep(double timeIntervalInSeconds) override;

        unsigned int GetNumberOfSubTimeSteps(double timeIntervalInSeconds) const override;

        virtual void OnBeginAdvanceTimeStep(double timeIntervalInSeconds);

        virtual void OnEndAdvanceTimeStep(double timeIntervalInSeconds);

        virtual void ComputeExternalForces(double timeIntervalInSeconds);

        virtual void ComputeViscosity(double timeIntervalInSeconds);

        virtual void ComputePressure(double timeIntervalInSeconds);

        virtual void ComputeAdvection(double timeIntervalInSeconds);

        virtual ScalarField2Ptr GetFluidSDF() const;

        void ComputeGravity(double timeIntervalInSeconds);

        void ApplyBoundaryCondition() const;

        void ExtrapolateIntoCollider(ScalarGrid2* grid);

        void ExtrapolateIntoCollider(CollocatedVectorGrid2* grid);

        void ExtrapolateIntoCollider(FaceCenteredGrid2* grid);

        ScalarField2Ptr GetColliderSDF() const;

        VectorField2Ptr GetColliderVelocityField() const;

    private:
        Vector2D m_gravity = Vector2D(0.0, -9.8);
        double m_viscosityCoefficient = 0.0;
        double m_maxCFL = 5.0;
        bool m_useCompressedLinearSys = false;
        int m_closedDomainBoundaryFlag = DIRECTION_ALL;

        GridSystemData2Ptr m_grids;
        Collider2Ptr m_collider;
        GridEmitter2Ptr m_emitter;

        AdvectionSolver2Ptr m_advectionSolver;
        GridDiffusionSolver2Ptr m_diffusionSolver;
        GridPressureSolver2Ptr m_pressureSolver;
        GridBoundaryConditionSolver2Ptr m_boundaryConditionSolver;

        void BeginAdvanceTimeStep(double timeIntervalInSeconds);

        void EndAdvanceTimeStep(double timeIntervalInSeconds);

        void UpdateCollider(double timeIntervalInSeconds) const;

        void UpdateEmitter(double timeIntervalInSeconds) const;
    };

    using GridFluidSolver2Ptr = std::shared_ptr<GridFluidSolver2>;
    
    template <typename DerivedBuilder>
    class GridFluidSolverBuilderBase2
    {
    public:
        DerivedBuilder& WithResolution(const Size2& resolution);

        DerivedBuilder& WithGridSpacing(const Vector2D& gridSpacing);

        DerivedBuilder& WithGridSpacing(double gridSpacing);

        DerivedBuilder& WithDomainSizeX(double domainSizeX);

        DerivedBuilder& WithOrigin(const Vector2D& gridOrigin);

    protected:
        Size2 m_resolution{ 1, 1 };
        Vector2D m_gridSpacing{ 1, 1 };
        Vector2D m_gridOrigin{ 0, 0 };
        double m_domainSizeX = 1.0;
        bool m_useDomainSize = false;

        Vector2D GetGridSpacing() const;
    };

    template <typename T>
    T& GridFluidSolverBuilderBase2<T>::WithResolution(const Size2& resolution)
    {
        m_resolution = resolution;
        return static_cast<T&>(*this);
    }

    template <typename T>
    T& GridFluidSolverBuilderBase2<T>::WithGridSpacing(const Vector2D& gridSpacing)
    {
        m_gridSpacing = gridSpacing;
        m_useDomainSize = false;
        return static_cast<T&>(*this);
    }

    template <typename T>
    T& GridFluidSolverBuilderBase2<T>::WithGridSpacing(double gridSpacing)
    {
        m_gridSpacing.x = gridSpacing;
        m_gridSpacing.y = gridSpacing;
        m_useDomainSize = false;
        return static_cast<T&>(*this);
    }

    template <typename T>
    T& GridFluidSolverBuilderBase2<T>::WithDomainSizeX(double domainSizeX)
    {
        m_domainSizeX = domainSizeX;
        m_useDomainSize = true;
        return static_cast<T&>(*this);
    }

    template <typename T>
    T& GridFluidSolverBuilderBase2<T>::WithOrigin(const Vector2D& gridOrigin)
    {
        m_gridOrigin = gridOrigin;
        return static_cast<T&>(*this);
    }

    template <typename T>
    Vector2D GridFluidSolverBuilderBase2<T>::GetGridSpacing() const
    {
        Vector2D gridSpacing = m_gridSpacing;
        
        if (m_useDomainSize)
        {
            gridSpacing.Set(m_domainSizeX / static_cast<double>(m_resolution.x));
        }

        return gridSpacing;
    }

    class GridFluidSolver2::Builder final : public GridFluidSolverBuilderBase2<GridFluidSolver2::Builder>
    {
    public:
        GridFluidSolver2 Build() const;

        GridFluidSolver2Ptr MakeShared() const
        {
            return std::make_shared<GridFluidSolver2>(m_resolution, GetGridSpacing(), m_gridOrigin);
        }
    };
}

#endif