FDMMGLinearSystem2-Impl.h

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/*************************************************************************
> File Name: FDMMGLinearSystem2-Impl.h
> Project Name: CubbyFlow
> Author: Chan-Ho Chris Ohk
> Purpose: Multigrid-syle 2-D linear system.
> Created Time: 2017/11/02
> Copyright (c) 2018, Chan-Ho Chris Ohk
*************************************************************************/
#ifndef CUBBYFLOW_FDM_MG_LINEAR_SYSTEM2_IMPL_H
#define CUBBYFLOW_FDM_MG_LINEAR_SYSTEM2_IMPL_H

namespace CubbyFlow
{
    template <typename T>
    void FDMMGUtils2::ResizeArrayWithCoarsest(const Size2& coarsestResolution,
        size_t numberOfLevels, std::vector<Array2<T>>* levels)
    {
        numberOfLevels = std::max(numberOfLevels, ONE_SIZE);

        levels->resize(numberOfLevels);

        // Level 0 is the finest level, thus takes coarsestResolution ^ numberOfLevels.
        // Level numberOfLevels - 1 is the coarsest, taking coarsestResolution.
        Size2 res = coarsestResolution;
        for (size_t level = 0; level < numberOfLevels; ++level)
        {
            (*levels)[numberOfLevels - level - 1].Resize(res);
            res.x = res.x << 1;
            res.y = res.y << 1;
        }
    }

    template <typename T>
    void FDMMGUtils2::ResizeArrayWithFinest(const Size2& finestResolution,
        size_t maxNumberOfLevels, std::vector<Array2<T>>* levels)
    {
        Size2 res = finestResolution;
        size_t i = 1;

        for (; i < maxNumberOfLevels; ++i)
        {
            if (res.x % 2 == 0 && res.y % 2 == 0)
            {
                res.x = res.x >> 1;
                res.y = res.y >> 1;
            }
            else
            {
                break;
            }
        }

        ResizeArrayWithCoarsest(res, i, levels);
    }
}

#endif