Z-fighting between flowing river water and water source

[Wuzzy2]

If you place a flowing river water on top of a water source, or a flowing water on top of a river water source, and you walk inside the source liquid to see the part where the upper liquid touches the bottom liuqid, and then you move the camera around, you will see z-fighting.

Screenshot

https://www.satoshiupload.com/images/4KXnqG99Pz.png

Steps to reproduce

• Place a (normal) water source on the floor
• Place a river water above, in such a way that a flowing river water node will appear right above the water source
• Go inside the water and look up to see the intersection of both liquids
• Move the camera slightly around

Expected: No z-fighting
Actual result: Z-fighting

Version

• Minetest Game: 5.5.0
• Minetest: 5.5.0

See also

minetest/minetest#9323

This might be a bug in Minetest, but I am not sure. Maybe there is also a way to fix this in the game code, with no engine change required? I'm not sure.

[appgurueu]

Maybe there is also a way to fix this in the game code, with no engine change required?

Any such way would require slightly offsetting the source node faces which would be hacky, presumably introducing new kinds of visual bugs. I say this needs an engine change.