Add bonemealing callback for dirt with grass.

* Add new file mcl_flowers/bonemeal.lua, containing the bonemealing
  callback for "mcl_core:dirt_with_grass".
* Override "mcl_core:dirt_with_grass" with a _mcl_on_bonemealing handler
  calling a function defined in mcl_flowers. This sidesteps the problem
  that bonemealing a node from mcl_core needs knowledge of mcl_flowers,
  which would create a circular dependency.  H/t to cora for suggesting
  this solution. H/t to wsor for suggesting a solution that also works.

mods/ITEMS/mcl_flowers/bonemealing.lua

@@ -0,0 +1,123 @@
+-- bonemealing grass nodes
+--
+-- When bonemealing "mcl_core:dirt_with_grass", it spawns grass and flowers
+-- over a 7x7 patch of adjacent grassy nodes.
+--
+-- Because of potential dependency complications it is not advisable to add
+-- callbacks to mcl_core that create dependencies on mods that depend on
+-- mcl_core, such as mcl_flowers.
+--
+-- To work around this restriction, the bonemealing callback is defined here
+-- and the _mcl_on_bonemealing callback in "mcl_core:dirt_with_grass" node
+-- definition is overwritten with it.
+
+local mg_name = minetest.get_mapgen_setting("mg_name")
+
+local flowers_table_simple = {
+	"mcl_flowers:dandelion",
+	"mcl_flowers:poppy",
+}
+local flowers_table_plains = {
+	"mcl_flowers:dandelion",
+	"mcl_flowers:dandelion",
+	"mcl_flowers:poppy",
+	"mcl_flowers:oxeye_daisy",
+	"mcl_flowers:tulip_orange",
+	"mcl_flowers:tulip_red",
+	"mcl_flowers:tulip_white",
+	"mcl_flowers:tulip_pink",
+	"mcl_flowers:azure_bluet",
+}
+local flowers_table_swampland = {
+	"mcl_flowers:blue_orchid",
+}
+local flowers_table_flower_forest = {
+	"mcl_flowers:dandelion",
+	"mcl_flowers:poppy",
+	"mcl_flowers:oxeye_daisy",
+	"mcl_flowers:tulip_orange",
+	"mcl_flowers:tulip_red",
+	"mcl_flowers:tulip_white",
+	"mcl_flowers:tulip_pink",
+	"mcl_flowers:azure_bluet",
+	"mcl_flowers:allium",
+}
+
+local biome_flowers_tables = {
+	["Plains"] = flowers_table_plains,
+	["Plains_beach"] = flowers_table_plains,
+	["Plains_ocean"] = flowers_table_plains,
+	["Plains_deep_ocean"] = flowers_table_plains,
+	["Plains_underground"] = flowers_table_plains,
+	["SunflowerPlains"] = flowers_table_plains,
+	["SunflowerPlains_ocean"] = flowers_table_plains,
+	["SunflowerPlains_deep_ocean"] = flowers_table_plains,
+	["SunflowerPlains_underground"] = flowers_table_plains,
+	["Swampland"] = flowers_table_swampland,
+	["Swampland_shore"] = flowers_table_swampland,
+	["Swampland_ocean"] = flowers_table_swampland,
+	["Swampland_deep_ocean"] = flowers_table_swampland,
+	["Swampland_underground"] = flowers_table_swampland,
+	["FlowerForest"] = flowers_table_flower_forest,
+	["FlowerForest_beach"] = flowers_table_flower_forest,
+	["FlowerForest_ocean"] = flowers_table_flower_forest,
+	["FlowerForest_deep_ocean"] = flowers_table_flower_forest,
+	["FlowerForest_underground"] = flowers_table_flower_forest,
+}
+
+-- Randomly generate flowers, tall grass or nothing
+-- pos: node to place into
+-- color: param2 value for tall grass
+--
+local function add_random_flower(pos, color)
+	-- 90% tall grass, 10% flower
+	if math.random(1,100) <= 90 then
+		minetest.add_node(pos, {name="mcl_flowers:tallgrass", param2=color})
+	else
+		local flowers_table
+		if mg_name == "v6" then
+			flowers_table = flowers_table_plains
+		else
+			local biome = minetest.get_biome_name(minetest.get_biome_data(pos).biome)
+			flowers_table = biome_flowers_tables[biome] or flowers_table_simple
+		end
+		minetest.add_node(pos, {name=flowers_table[math.random(1, #flowers_table)]})
+	end
+end
+
+--- Generate tall grass and random flowers in a 7x7 area
+-- Bonemealing callback handler for "mcl_core:dirt_with_grass"
+--
+local function bonemeal_grass(pointed_thing, placer)
+	local pos, below, r, color
+	for i = -7, 7 do for j = -7, 7 do for y = -1, 1 do
+		pos = vector.offset(pointed_thing.above, i, y, j)
+		if minetest.get_node(pos).name == "air" then
+			below = minetest.get_node(vector.offset(pos, 0, -1, 0))
+			r = ((math.abs(i) + math.abs(j)) / 2)
+			if (minetest.get_item_group(below.name, "grass_block_no_snow") == 1) and
+					math.random(1, 100) <= 90 / r then
+				color = below.param2
+				add_random_flower(pos, color)
+			end
+		end
+	end end end
+	return true
+end
+
+-- Overwrite "mcl_core:dirt_with_grass" bonemealing handler.
+local nodename = "mcl_core:dirt_with_grass"
+local olddef = minetest.registered_nodes[nodename]
+if not olddef then
+	minetest.log("warning", "'mcl_core:dirt_with_grass' not registered, cannot add override!")
+else
+	local oldhandler = olddef._mcl_on_bonemealing
+	local newdef = table.copy(olddef)
+	newdef._mcl_on_bonemealing = function (pointed_thing, placer)
+		bonemeal_grass(pointed_thing, placer)
+		if oldhandler then
+			oldhandler(pointed_thing, placer)
+		end
+	end
+	minetest.register_node(":" .. nodename, newdef)
+end

mods/ITEMS/mcl_flowers/init.lua

@@ -572,3 +572,6 @@ if mod_mcimport and mg_name == "singlenode" and fix_doubleplants == true then
 end
 
 dofile(modpath.."/register.lua")
+
+-- Bonemealing handler and override for "mcl_core:dirt_with_grass":
+dofile(modpath.."/bonemealing.lua")