Unclear how to use paramtype2 = "flowingliquid"

[SnoutBug]

Luanti version

Luanti 5.10.0 Flatpak

Operating system and version

Flatpak

CPU model

No response

GPU model

No response

Active renderer

No response

Summary

In the documentation it says:

• paramtype2 = "flowingliquid"
  Used by drawtype = "flowingliquid" and liquidtype = "flowing"
  The liquid level and a flag of the liquid are stored in param2
  Bits 0-2: Liquid Level (0-7). The higher, the more liquid is in this node; see core.get_node_level, core.set_node_level and core.add_node_level to access/manipulate the content of this field

Though, following these instructions, I was not able to change the liquid level of the node.

Steps to reproduce

local flowing = core.registered_nodes["default:water_flowing"]

core.register_node("test_water:test",  {
    	name        = "test_water:test",
        description = "Test Water",
	paramtype2  = "flowingliquid",
	
	drawtype   = "flowingliquid", -- Used by drawtype = "flowingliquid"
	liquidtype = "source",        -- Flowing not needed here since condition is already met?
	
	tiles 		  = flowing.tiles,		-- As needed by drawtype - copy from water
	special_tiles     = flowing.special_tiles,
	use_texture_alpha = flowing.use_texture_alpha, 
	
	liquid_renewable = false,			-- Disallow any kind of spreading
	liquid_range     = 0,
	
	buildable_to = true,				-- For removing

        liquid_alternative_flowing = "test_water:test",	-- As requested in documentation

})

core.register_abm {
        nodenames = "test_water:test",
        neighbors = "air",
        interval  = 0.2,
        chance    = 0,
        action = function(pos, node, active_object_count, active_object_count_wider)
            core.set_node_level(pos, math.random(1,7)) -- This should make the liquid "dance"
        end,
}

[cx384]

The documentation:

Used by drawtype = "flowingliquid" and liquidtype = "flowing"

What you use:

drawtype   = "flowingliquid",
liquidtype = "source",  

Difference: "source "~= "flowing"

Maybe the documentation could be improved to clearly indicate that the "and" means both?

Edit:
It happens here:
https://github.com/minetest/minetest/blob/2bfcd45b35d9e64cbbe54827c4d58d3b5082299a/src/mapnode.cpp#L477-L480

So it does only not work for liquidtype = "source"

[SnoutBug]

I see, that makes sense. Reading the comments I am guessing that this is supposed to change in the future?

Edit: is there a possible workaround you can imagine, so that I can use the smooth leveling of flowing liquids for any arbitrary node?

[cx384]

is there a possible workaround you can imagine, so that I can use the smooth leveling of flowing liquids for any arbitrary node?

Removing liquidtype = "source", or setting liquidtype = "none", should work. It is possible since #10737.
But note that the level appearance still depends on the adjacent nodes and liquid_range, so your liquid_range = 0, may not work well, and you have to place multiple flowing liquids next to each other, I think.

[SnoutBug]

That works quite well. Thanks.

Though there are some remaining issues:

1. The one you mentioned: the level is still dependent on liquid_range. I think this causes the liquid level to appear lower than it actually should be.
2. Error message for liquids with liquid_range of 0 #12593 when not setting liquid_alternative_source. Setting this parameter (in the example above to test_water:test) seems to disable the leveling - or at least permanently fixing it at the maximum height which could also be caused by 1.