Distorted Android

      buf.position((         i)*width*4);  // GL uses a coordinate system from mathematics; i.e.

      buf.get(tmp1);                       // (0,0) is in the lower-left corner. 2D stuff has

      buf.position((height-1-i)*width*4);  // the origin on the upper-left corner; we have to flip

      buf.position((         i)*width*4);

      buf.put(tmp2);