OpenGL中Texture数据的顺序
The first element corresponds to the lower left corner of the texture image. Subsequent elements progress left-to-right through the remaining texels in the lowest row of the texture image, and then in successively higher rows of the texture image. The final element corresponds to the upper right corner of the texture image.
buffer中第一个元素代表左下角，从左到右处理，最后一个元素代表右上角