happy new year!
  here is the question .  I have many text boards to show. 
  1 which is better way to save memory , create a Object3D for each text  or create only one Object3D for all of text?
  2 if i created only one Object3D , how to hide part of this Object3D ? I have tried  get polygon id and using setVertexAlpha(polygonid, alpha) to archive this effect. it seems not work verywell,
    only first of call is work.  (this problem only on android )

Docments  saids : "Pollyline will be rendered after all objects have been drawn."
and It is true . see attachment, some lines is on the top of the circle. The circle object has been set to be transparent.

But if I disable the transparent of the circle. The PollyLine will not on top of the circle.  Is it by design?
How can I avoid this situation.

thanks for any comments.

if i set up an ambient light, the scene looks like this:  the surface of the cube all are brightness , see attachment bad.png
i want it looks like good.png , but i can't find direct light to implement that effect.

help me out pls