利用OpenGL绘制不断旋转的生日蛋糕。应用工具库中的圆柱体、球，通过使用旋转、平移、放大缩小等方法变换坐标，组成蛋糕、蜡烛、火焰等相应物体。-Using OpenGL drawing birthday cake constantly rotating. Utility library cylinders, spheres, through the use of rotating, panning, zooming and other methods transform coordinates