// テクスチャから初期化する
        // w 横の画像数
        // h 縦の画像数
        public AnimationNode(String name, int w, int h, double sec, CGSize size)
        {
            textures = new SKTexture[w * h];
            var texture = SKTexture.FromImageNamed(name);
            var c       = 0;

            for (var y = h - 1; y >= 0; y--)
            {
                for (var x = 0; x < w; x++)
                {
                    textures[c++] = SKTexture.FromRectangle(new CGRect(x / (float)w, y / (float)h, 1 / (float)w, 1 / (float)h), texture);
                }
            }
            node           = SKSpriteNode.FromTexture((SKTexture)textures[0]);
            node.Size      = size;
            node.ZPosition = 1;
            node.Position  = new CGPoint(-100, -100);
            action         = SKAction.AnimateWithTextures((SKTexture[])textures, sec);
        }