dl_tilemap.h

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#pragma once

namespace dl::TileMap
{
    template<Position TILE_SIZE>
    class Rectangle
    {
    public:
        constexpr Position Map2World(const Point& xy)
        {
            return toPosition(xy) * TILE_SIZE;
        }
        constexpr Position Map2World(const PointU& xy)
        {
            return Map2World(toPoint(xy));
        }

        constexpr Point World2Map(const Position& pos)
        {
            return toPoint(pos / TILE_SIZE);
        }
 
        constexpr Position GetSize() { return TILE_SIZE; }
    };

    template<Position TILE_SIZE>
    class DiamondSlant
    {
    public:
        constexpr Position Map2World(const Point& xy)
        {
            return { (xy[1] + xy[0]) * TILE_SIZE[0] / 2.0_f,  (xy[1] - xy[0]) * TILE_SIZE[1] / 2.0_f };
        }

        constexpr Point World2Map(const Position& pos)
        {
            Position xy_div = pos / TILE_SIZE;
            return toPoint(Position{ xy_div[0] - xy_div[1] + 0.5_f, xy_div[0] + xy_div[1] - 0.5_f });
        }

        constexpr Position GetSizeBound(const Size& size)
        {
            constexpr Position TILE_SIZE_HALF = TILE_SIZE / 2.0_f;
            unsigned sum = size[0] + size[1];
            return TILE_SIZE_HALF * (Float)sum;
        }
    };

    template<Position TILE_SIZE>
    class DiamondFlat
    {
    public:
        constexpr Position Map2World(const Point& xy)
        {
            Position pos = { TILE_SIZE[0] * xy[0] , TILE_SIZE[1] / 2 * xy[1] };
            if (xy[1] % 2 != 0)
            {//奇数行向右偏移 w / 2
                pos[0] += TILE_SIZE[0] / 2;
            }
            return pos;
        }

        constexpr Point World2Map(const Position& pos)
        {
            constexpr Position TILE_SIZE_HALF = TILE_SIZE / 2.0_f;
            //四分之一矩形面积
            constexpr Float s = Accumulate::Mul(TILE_SIZE_HALF);
            //先计算矩形下标
            Point p = toPoint(pos / TILE_SIZE);
            //在矩形内坐标
            Position p1 = pos - toPosition(p) * TILE_SIZE - TILE_SIZE_HALF;
            //点围成矩形面积
            Float sp = std::fabs(p1[0] * TILE_SIZE_HALF[1])
                + std::fabs(p1[1] * TILE_SIZE_HALF[0]);
            p[1] *= 2;
            if (s < sp)
            {
                if (p1[0] > 0 && p1[1] > 0)
                    return p + Point{ 0, 1 };
                else if (p1[0] < 0 && p1[1] > 0)
                    return p + Point{ -1, 1 };
                else if (p1[0] < 0 && p1[1] < 0)
                    return p + Point{ -1, -1 };
                else if (p1[0] > 0 && p1[1] < 0)
                    return  p + Point{ 0, -1 };
                else
                    return p;
            }
            else
            {
                return p;
            }
        }
    };
}