Added can_grow function to plant definition (#3131)

game_api.txt

@@ -382,6 +382,8 @@ The farming API allows you to easily register plants and hoes.
 		-- ^ Always provide a plant texture for each step, format: modname_plantname_i.png (i = stepnumber)
 		minlight = 13,                         -- Minimum light to grow
 		maxlight = default.LIGHT_MAX           -- Maximum light to grow
+		can_grow = function(pos)               -- Сalled every growth tick to check if the plant can grow, returns bool
+		                                       -- (optional, checks for wet soil by default)
 	}
 
 

mods/farming/api.lua

@@ -189,6 +189,12 @@ farming.place_seed = function(itemstack, placer, pointed_thing, plantname)
 	return itemstack
 end
 
+-- check if on wet soil
+farming.can_grow = function(pos)
+	local below = minetest.get_node(pos:offset(0, -1, 0))
+	return minetest.get_item_group(below.name, "soil") >= 3
+end
+
 farming.grow_plant = function(pos, elapsed)
 	local node = minetest.get_node(pos)
 	local name = node.name
@@ -224,9 +230,7 @@ farming.grow_plant = function(pos, elapsed)
 		return
 	end
 
-	-- check if on wet soil
-	local below = minetest.get_node({x = pos.x, y = pos.y - 1, z = pos.z})
-	if minetest.get_item_group(below.name, "soil") < 3 then
+	if not (def.can_grow or farming.can_grow)(pos) then
 		tick_again(pos)
 		return
 	end