Shared WebGL context

[superivaj]

maptalks's version and what browser you use?
v0.43.0, chrome

Issue description
Layers do not share WebGL context, which creates glitches when a map has more than one 3d layer. For example a buildings layer with a 3D line will not hide the line behind the buildings.
In particular, I am implementing a 3D terrain layer but this layer will not hide (behind mountains) any other 3d element in the map, such as buildings.

Please provide a reproduction URL (on any jsfiddle like site)
The following example fraws two vector layers. Due to the WebGL context not being shared, the rendering is wrong.
http://jsfiddle.net/h6z5jtky/2/

[fuzhenn]

Yeah, indeed.
We are working on a new layer to solve this issue in a decent way.
It should be ready in 1 or 2 months, I will update here once it's ready.

[superivaj]

Thank you for the quick response fuzhenn.
Is there a branch or discussion thread that I can monitor and contribute to solve this issue?