長方形の影

# include <Siv3D.hpp>

Rect MakeRect(int32 x, int32 y)
{
    return{ 60 + x * 105, 30 + 105 * y, 100, 100 };
}

void Main()
{
    Graphics::SetBackground(Palette::White);

    Grid<double> z(5, 4);

    while (System::Update())
    {
        for (int32 y = 0; y < z.height; ++y)
        {
            for (int32 x = 0; x < z.width; ++x)
            {
                const Rect rect = MakeRect(x, y);

                if (!rect.mouseOver)
                {
                    rect.draw(HSV(75 * (y * 4 + x), 0.7, 0.95));

                    z[y][x] = Max(z[y][x] - 0.02, 0.0);
                }
            }
        }

        for (int32 y = 0; y < z.height; ++y)
        {
            for (int32 x = 0; x < z.width; ++x)
            {
                const Rect rect = MakeRect(x, y);

                if (rect.mouseOver || z[y][x])
                {
                    if (rect.mouseOver)
                        z[y][x] = Min(z[y][x] + 0.05, 1.0);

                    const double s = z[y][x];

                    RectF(rect).stretched(s * 1).drawShadow({ 0, 8 * s }, 28 * s, 6 * s);

                    RectF(rect).stretched(s * 1).draw(HSV(75 * (y * 4 + x), 0.7, 0.95 + s * 0.05));
                }
            }
        }
    }
}