说明：  本例vrml代码需要专门的vrml浏览器浏览，本例代码是渐变旋转的十字架模型，可以利用此例改编其他渐变旋转造型，非常实用
(This case vrml code needs specialized vrml browser browsing this case, the code is the model of the the gradient rotation of the cross, you can take advantage of this case adapted to other gradient rotation modeling is very useful)