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void ParticleManager::computeDensitypressureOptimised()
{
    for (int i = 0; i < _indexes.size(); ++i)
    {
        for (int y = -1; y <= 1; ++y)
        {
            for (int x = -1; x <= 1; ++x)
            {
                if (_indexes[i] + x + y * COLUMN < 0 || _indexes[i] + x + y * COLUMN > GRIDMAX) { continue; }
                for (int pi = 0; pi < _grid[_indexes[i] + x + y * COLUMN].size(); ++pi)
                {
                    _grid[_indexes[i] + x + y * COLUMN][pi]->rho = 0.f;
                    for (int pj = 0; pj < _grid[_indexes[i] + x + y * COLUMN].size(); ++pj)
                    {
                        auto ppi = _grid[_indexes[i] + x + y * COLUMN][pi];
                        auto ppj = _grid[_indexes[i] + x + y * COLUMN][pj];
                        double distanceSquared = (ppj->x - ppi->x) * (ppj->x - ppi->x) + (ppj->y - ppi->y) * (ppj->y - ppi->y);
                        if (distanceSquared < HSQ)
                        {
                            ppi->rho += MASS * POLY6 * (HSQ - distanceSquared) * (HSQ - distanceSquared) * (HSQ - distanceSquared);
                        }
                    }
                    _grid[_indexes[i] + x + y * COLUMN][pi]->p = GAS_CONST * (_grid[_indexes[i] + x + y * COLUMN][pi]->rho - REST_DENS);
                }
            }
        }
    }
}

void ParticleManager::computeForcesOptimised()
{
    for (int i = 0; i < _indexes.size(); ++i)
    {
        for (int y = -1; y <= 1; ++y)
        {
            for (int x = -1; x <= 1; ++x)
            {
                if (_indexes[i] + x + y * COLUMN < 0 || _indexes[i] + x + y * COLUMN > GRIDMAX) { continue; }
                {
                    for (int pi = 0; pi < _grid[_indexes[i] + x + y * COLUMN].size(); ++pi)
                    {
                        double pressure_x = 0.f;
                        double pressure_y = 0.f;
                        double viscosity_x = 0.f;
                        double viscosity_y = 0.f;

                        for (int pj = 0; pj < _grid[_indexes[i] + x + y * COLUMN].size(); ++pj)
                        {
                            if (&_grid[_indexes[i] + x + y * COLUMN][pi] == &_grid[_indexes[i] + x + y * COLUMN][pj])
                                continue;

                            auto ppi = _grid[_indexes[i] + x + y * COLUMN][pi];
                            auto ppj = _grid[_indexes[i] + x + y * COLUMN][pj];

                            double rsqr = ((ppj->x - ppi->x) * (ppj->x - ppi->x) + (ppj->y - ppi->y) * (ppj->y - ppi->y));

                            if (rsqr < HSQ)
                            {
                                double r = sqrt(rsqr);
                                double fpress = MASSxSPIKY * (ppi->p + ppj->p) / (2.0 * ppj->rho) * (HSQ - 2 * H * r + rsqr);
                                pressure_x += (ppi->x - ppj->x) / r * fpress;
                                pressure_y += (ppi->y - ppj->y) / r * fpress;
                                viscosity_x += VISCxMASSxVISC_LAP * (ppj->vx - ppi->vx) / ppj->rho * (H - r);
                                viscosity_y += VISCxMASSxVISC_LAP * (ppj->vy - ppi->vy) / ppj->rho * (H - r);
                            }
                        }
                        _grid[_indexes[i] + x + y * COLUMN][pi]->fx = pressure_x + viscosity_x + _ax * _grid[_indexes[i] + x + y * COLUMN][pi]->rho;
                        _grid[_indexes[i] + x + y * COLUMN][pi]->fy = pressure_y + viscosity_y + _ay * _grid[_indexes[i] + x + y * COLUMN][pi]->rho;
                    }
                }
            }
        }
    }
}