VoxeLibre/mods/MAPGEN/vl_biomes/deco/tallgrass.lua

-- Template to register a grass decoration
local function register_grass_decoration(offset, scale, biomes)
	for b = 1, #biomes do
		local param2 = minetest.registered_biomes[biomes[b]]._mcl_grass_palette_index
		mcl_mapgen_core.register_decoration({
			deco_type = "simple",
			priority = 1500,
			place_on = {"group:grass_block_no_snow", "mcl_mud:mud"},
			sidelen = 16,
			noise_params = {
				offset = offset,
				scale = scale,
				spread = vector.new(200, 200, 200),
				seed = 420,
				octaves = 3,
				persist = 0.6
			},
			biomes = { biomes[b] },
			y_min = 1,
			y_max = vl_biomes.overworld_max,
			decoration = "mcl_flowers:tallgrass",
			param2 = param2,
		})
	end
end

local grass_forest = {"Plains", "Taiga", "Forest", "FlowerForest", "BirchForest", "BirchForestM", "RoofedForest", "Swampland", }
local grass_mpf = {"MesaPlateauF_grasstop"}
local grass_plains = {"Plains", "SunflowerPlains", "JungleEdge", "JungleEdgeM", "MangroveSwamp"}
local grass_savanna = {"Savanna", "SavannaM"}
local grass_sparse = {"ExtremeHills", "ExtremeHills+", "ExtremeHills+_snowtop", "ExtremeHillsM", "Jungle"}
local grass_mpfm = {"MesaPlateauFM_grasstop"}

-- TODO: register only once for each biome, with better parameters?
register_grass_decoration(-0.03, 0.09, grass_forest)
register_grass_decoration(-0.015, 0.075, grass_forest)
register_grass_decoration(0, 0.06, grass_forest)
register_grass_decoration(0.015, 0.045, grass_forest)
register_grass_decoration(0.03, 0.03, grass_forest)
register_grass_decoration(-0.03, 0.09, grass_mpf)
register_grass_decoration(-0.015, 0.075, grass_mpf)
register_grass_decoration(0, 0.06, grass_mpf)
register_grass_decoration(0.01, 0.045, grass_mpf)
register_grass_decoration(0.01, 0.05, grass_forest)
register_grass_decoration(0.03, 0.03, grass_plains)
register_grass_decoration(0.05, 0.01, grass_plains)
register_grass_decoration(0.07, -0.01, grass_plains)
register_grass_decoration(0.09, -0.03, grass_plains)
register_grass_decoration(0.18, -0.03, grass_savanna)
register_grass_decoration(0.05, -0.03, grass_sparse)
register_grass_decoration(0.05, 0.05, grass_mpfm)
register_grass_decoration(-0.03, 1, {"BambooJungle", "BambooJungleM", "BambooJungleEdge"})

-- Doubletall grass registration helper
local function register_doubletall_grass(offset, scale, biomes)
	for b = 1, #biomes do
		local param2 = minetest.registered_biomes[biomes[b]]._mcl_grass_palette_index
		mcl_mapgen_core.register_decoration({
			deco_type = "schematic",
			priority = 1500,
			schematic = {
				size = vector.new(1, 3, 1),
				data = {
					{name = "air", prob = 0},
					{name = "mcl_flowers:double_grass", param1 = 255, param2 = param2},
					{name = "mcl_flowers:double_grass_top", param1 = 255, param2 = param2},
				},
			},
			place_on = {"group:grass_block_no_snow"},
			sidelen = 16,
			noise_params = {
				offset = offset,
				scale = scale,
				spread = vector.new(200, 200, 200),
				seed = 420,
				octaves = 3,
				persist = 0.6,
			},
			y_min = 1,
			y_max = vl_biomes.overworld_max,
			biomes = biomes,
		})
	end
end

register_doubletall_grass(-0.0005, -0.3, {"BambooJungle", "BambooJungleM", "BambooJungleEdge"})
register_doubletall_grass(-0.01, 0.03, {"Forest", "FlowerForest", "BirchForest", "BirchForestM", "RoofedForest", "Taiga"})
register_doubletall_grass(-0.002, 0.03, {"Plains", "SunflowerPlains"})
register_doubletall_grass(-0.0005, -0.03, {"Savanna", "SavannaM"})

mcl_mapgen_core.register_decoration({
	deco_type = "simple",
	priority = 1500,
	place_on = {"group:grass_block_no_snow"},
	sidelen = 16,
	noise_params = {
		offset = 0,
		scale = 0.012,
		spread = vector.new(100, 100, 100),
		seed = 354,
		octaves = 1,
		persist = 0.5,
		lacunarity = 1.0,
		flags = "absvalue"
	},
	biomes = {"BambooJungle", "BambooJungleEdge","BambooJungleM", "BambooJungleEdge"},
	y_max = vl_biomes.overworld_max,
	y_min = 1,
	decoration = "mcl_flowers:tallgrass"
})