Yes, grab the buffer and modify it. Which part is tripping you up?
Edit: note that you are probably better off just making your own mesh so that you know where everything is rather than trying to modify JME’s Box mesh directly. If JME ever chose to reorder its vertexes or something then that would mess you up.
Edit 2: also what do you mean by ‘move the top face down’? Do you mean shrink the cube in one direction or move the top face down but leave the sides intact and strange?
why I can’t get the float array of vertices using FloatBuffer.array() method?
and it throws an exception:
SEVERE: Uncaught exception thrown in Thread[jME3 Main,5,main]
…and then reading between the lines. It’s because a native FloatBuffer doesn’t have a backing float array.
Also, shuffling the buffer from FloatBuffer to float and back is going to be the least efficient way of updating the float buffer because you will have to copy the entire buffer to Java heap and then end up copying it all back again to native heap.
Better just to learn to deal with the FloatBuffer in the end.