Is there a way of exclude some geometry from global-clipping?

Questions
1

I have a complex scene which has a lot of objects and materials, and I want to add clip-plane to this scene, I know there are two ways of add clipping, global way is by renderer, and add all these planes to materials clipplane, this is local.

because I have a lot of objects and material, iterate all the materials to add these clip plane is a time consuming task, but if I use the global clipping plane, then the TransformControls of those plane will also be clipped, so I wonder if there is some better solution for this, I want to clip many objects but exclude some of the objects, especially to exclude the planehelper and transformcontrols from being clipped.

How can we improve documentation?
2

really? whats wrong with
scene.traverse((object) => { if (object.material) { … do something to object.material; }});

3

thank you makc3d, just tested traverse, it seems fast enough for me, thank you again.

4

If you have ambient occlusion, how do you hide the shadows if you add planes to materials instead of the renderer?