Render an object only if the object is behind a specific object

Hello community,

I want to render an object (particles) only if they are behind an specific object. For example: I want to render bubbles in a liquid. The bubbles should be only visible if they are behind (or within) the "liquid mesh". I don't want to see the bubbles if I'm looking from the top through the liquid-surface (liquid-surface and liquid-mesh are different objects/materials in my scene). I'm well aware of the ZTest GEqual, but if I'm using this, the bubbles will be visible from everywhere. Therefore I adjusted the RenderQueue of some other objects. The renderqueue of my liquid surface is now 3100 and the renderqueue of the bubbles is 2500. Unfortunately if I'm looking from a specific angle (the camera is under the water-level) the surface is rendered in front of the bubbles.
Is there anyone out there who can point me in the right direction?
Help is very appreciated!

 

https://docs.unity3d.com/Manual/SL-Stencil.html

The stencil buffer is normally used for things like this.

 

Indeed, the stencil buffer is the way to go. This great post by supernat helped me make sense of them, hopefully it'll do the same for you.

 

Thank you. I solved my issue! This video is very good. The source code is in the decription:

 

hi