CSS2D/3DRenderer: Make the code more reasonable.

[lafflan]

IMO, i don't think it's necessary to traverse the entire scene every frame, only traverse and hide when object.visible === false is more reasonable.

[yomotsu]

As I mentioned before:
#28293 (comment)
I think ALL objects need to be hidden before rendering.

Therefore, this change might break the expected behavior.
Would you mind testing with nested CSS2D/3DObjects?

like
hidden object > visible object Should hide both objects. but the child may be rendered with this change.

[lafflan]

like
hidden object > visible object Should hide both objects. but the child may be rendered with this change.

I have tested in examples/css2d_label.html of both nested mesh > css2d and css2d > css2d situation, all results appear to meet expectations.

[mrdoob]

@lafflan Any chance you can share the code you used for testing that?

[lafflan]

@lafflan Any chance you can share the code you used for testing that?

OK. Test in https://jsfiddle.net/q8c6d2ym/6/

[yomotsu]

Sorry, I misunderstood.
Your PR is correct, since hideObject() works in the object tree (not DOM).

I also tested it with a simplified fork of your demo:
https://jsfiddle.net/dkyfct6o/
and it works too.

Very sorry.