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C-/C++-Quelltext

#pragma once
#define DEFAULT_SIZE (100)
#define DEFAULT_VISC (0.02f)
#define DEFAULT_EQUI (0.1f)

#define SQRT2 (0.70710678118654752440084436210485)

class OscFluid
{
public:
    OscFluid(const int NewSize = DEFAULT_SIZE, const float NewVisc = DEFAULT_VISC, const float NewEqui = DEFAULT_EQUI);
    ~OscFluid();
        
    int PosIdx(int x, int y); //convert position to index

    void Update();  

    const int Size;
    const int Area;
    const float Visc; //viscosity
    const float Equi; //equilibrium

    float* Press; //pressure
    float* Vel; //velocity

    float* Perm; //permeability 

private:
    inline void Solve(const int ThisIdx, const int OtherIdx, const float Amount);
    inline void Apply(const int ThisIdx);
};

C-/C++-Quelltext

#include "OscFluid.h"

OscFluid::OscFluid(const int NewSize, const float NewVisc, const float NewEqui) :
    Press(nullptr),
    Vel(nullptr),
    Perm(nullptr),
    Size(NewSize),
    Area(NewSize * NewSize),
    Visc(NewVisc),
    Equi(NewEqui)
{
    Press = new float[Area];
    Vel = new float[Area];
    Perm = new float[Area];

    for (int i = 0; i < Area; ++i)//default values
    {
        Press[i] = 0.5f;
        Vel[i] = 0.0;

        Perm[i] = 1.f;
    }
    for (int i = 0; i < Size; ++i)//walls, not permeable
    {
        Perm[PosIdx(i, 0)] = 0.f;
        Perm[PosIdx(i, Size - 1)] = 0.f;
        Perm[PosIdx(0, i)] = 0.f;
        Perm[PosIdx(Size - 1, i)] = 0.f;
    }
} 
OscFluid::~OscFluid()
{
    delete[] Press;
    delete[] Vel;
    delete[] Perm;
}
int OscFluid::PosIdx(const int X, const int Y)
{
    return X + Y * Size;
}
void OscFluid::Update()
{
    for (int ThisIdx = 0; ThisIdx < Area; ++ThisIdx)
    {
        if (Perm[ThisIdx] > 0.f)
        {
            Solve(ThisIdx, ThisIdx + 1, Equi);
            Solve(ThisIdx, ThisIdx - 1, Equi);
            Solve(ThisIdx, ThisIdx + Size, Equi);
            Solve(ThisIdx, ThisIdx - Size, Equi);

            Solve(ThisIdx, ThisIdx + 1 + Size, Equi * SQRT2 );
            Solve(ThisIdx, ThisIdx + 1 - Size, Equi * SQRT2 );
            Solve(ThisIdx, ThisIdx - 1 + Size, Equi * SQRT2 );
            Solve(ThisIdx, ThisIdx - 1 - Size, Equi * SQRT2 );
        }
    }
    for (int ThisIdx = 0; ThisIdx < Area; ++ThisIdx)
    {
        if (Perm[ThisIdx] > 0.f)
        {
            Apply(ThisIdx);
        }
    }
}
void OscFluid::Solve(const int ThisIdx, const int OtherIdx, const float Amount)
{
    const float Acc = (Press[ThisIdx] - Press[OtherIdx]) * Perm[OtherIdx] * Amount;
    Vel[OtherIdx] += Acc;
}
void OscFluid::Apply(const int ThisIdx)
{
    Press[ThisIdx] += Vel[ThisIdx];
    Vel[ThisIdx] *= (1.f - Visc);
}