How to obtain whether the current 3D object is blocked by other 3D objects

Questions
1

How to obtain whether the current 3D object is blocked by other 3D objects

When the current 3D object is occluded, I will hide its corresponding CSSLabel

like this:

image
image1022×650 39.8 KB

https://drei.pmnd.rs/?path=/story/misc-html--html-raycast-occluder-st

2

raycasting is one way, this is what <Html /> does. the code is here: drei/Html.tsx at 26a2d273b1d945e7a5645aaddac4da392007fa97 · pmndrs/drei · GitHub

3

Determining occlusion [ true, false, partially ] of a 3DObject is not a simple task, certainly not a cheap one. I see in the picture, there 2 spheres. That should make it easy to come up with a function to handle the job.

How the movement of spheres and camera are handled?