SmokeEvolution.h

Go to the documentation of this file.

// Copyright Epic Games, Inc. All Rights Reserved.
#pragma once
 
#include "Chaos/ArrayFaceND.h"
#include "Chaos/ArrayND.h"
#include "Chaos/KinematicGeometryParticles.h"
#include "Chaos/UniformGrid.h"
 
#include <cmath>
 
namespace Chaos
{
template<class T, int d>
class TSmokeEvolution
{
  public:
    TSmokeEvolution(const TUniformGrid<T, d>& Grid, TKinematicGeometryParticles<T, d>&& GeometryParticles, TKinematicGeometryParticles<T, d>&& SourceParticles)
        : MGrid(Grid), MVelocity(MGrid), MDensity(MGrid), MDirichlet(MGrid), MNeumann(MGrid), MCollisionParticles(MoveTemp(GeometryParticles)), MSourceParticles(MoveTemp(SourceParticles))
    {
        MVelocity.Fill(0);
        MDensity.Fill(0);
    }
    ~TSmokeEvolution() {}
 
    void AdvanceOneTimeStep(const T Dt);
 
    inline void AddForceFunction(TFunction<void(const TUniformGrid<T, d>&, TArrayFaceND<T, d>&, const T, const Pair<int32, TVector<int32, d>>)> ForceFunction) { MForceRules.Add(ForceFunction); }
    inline void SetAdvectionFunction(TFunction<void(const TUniformGrid<T, d>&, TArrayND<T, d>&, const TArrayND<T, d>&, const TArrayFaceND<T, d>&, const T, const TVector<int32, d>)> AdvectionFunction) { MAdvectionRule = AdvectionFunction; }
    inline void SetConvectionFunction(TFunction<void(const TUniformGrid<T, d>&, TArrayND<T, d>&, const TArrayND<T, d>&, const TArrayFaceND<T, d>&, const T, const TVector<int32, d>)> ConvectionFunction) { MConvectionRule = ConvectionFunction; }
    inline void SetProjectionFunction(TFunction<void(const TUniformGrid<T, d>&, TArrayFaceND<T, d>&, const TArrayND<bool, d>&, const TArrayFaceND<bool, d>&, const T)> ProjectionFunction) { MProjectionRule = ProjectionFunction; }
 
    inline const TUniformGrid<T, d>& Grid() const { return MGrid; }
    inline const TArrayFaceND<T, d>& Velocity() const { return MVelocity; }
    inline const TArrayND<T, d>& Density() const { return MDensity; }
    inline TArrayND<T, d>& Density() { return MDensity; }
 
    const T ComputeDivergence()
    {
        T Divergence = 0;
        for (int32 i = 0; i < MGrid.GetNumCells(); ++i)
        {
            T LocalDivergence = 0;
            for (int32 j = 0; j < d; ++j)
            {
                const TVector<int32, d> index = MGrid.GetIndex(i);
                LocalDivergence += (MVelocity(MakePair(j, MGrid.ClampIndex(index + TVector<int32, d>::AxisVector(j)))) - MVelocity(MakePair(j, index))) / MGrid.Dx()[j];
            }
            Divergence += FGenericPlatformMath::Abs(LocalDivergence);
        }
        return Divergence / (T)MGrid.Counts().Product();
    }
 
  private:
    TUniformGrid<T, d> MGrid;
    TArrayFaceND<T, d> MVelocity;
    TArrayND<T, d> MDensity;
    TArrayND<bool, d> MDirichlet;
    TArrayFaceND<bool, d> MNeumann;
    TKinematicGeometryParticles<T, d> MCollisionParticles, MSourceParticles;
 
    TArray<TFunction<void(const TUniformGrid<T, d>&, TArrayFaceND<T, d>&, const T, const Pair<int32, TVector<int32, d>>)>> MForceRules;
    TFunction<void(const TUniformGrid<T, d>&, TArrayND<T, d>&, const TArrayND<T, d>&, const TArrayFaceND<T, d>&, const T, const TVector<int32, d>)> MAdvectionRule;
    TFunction<void(const TUniformGrid<T, d>&, TArrayND<T, d>&, const TArrayND<T, d>&, const TArrayFaceND<T, d>&, const T, const TVector<int32, d>)> MConvectionRule;
    TFunction<void(const TUniformGrid<T, d>&, TArrayFaceND<T, d>&, const TArrayND<bool, d>&, const TArrayFaceND<bool, d>&, const T)> MProjectionRule;
};
}