Add biomeinfo mod

mods/CORE/biomeinfo/API.md

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+# Biome Info API
+This document explains the API of this mod.
+
+## v6 mapgen functions
+These are functions for the v6 mapgen only.
+
+Use these functions only in worlds in which the v6 mapgen is used.
+If you use these in any other mapgen, bad things might happen.
+
+### `biomeinfo.get_v6_humidity(pos)`
+Get the biome humidity at pos (for v6 mapgen).
+
+### `biomeinfo.get_v6_heat(pos)`
+Get the biome heat/temperature at pos (for v6 mapgen).
+
+### `biomeinfo.get_v6_biome(pos)`
+Get the v6 biome at pos.
+Returns a string, which is the unique biome name.
+
+Note: This function currently ignores the `biomeblend` v6 mapgen flag,
+it just pretends this setting is disabled.
+This is normally not a problem, but at areas where biomes blend,
+the result is not perfectly accurate and just an estimate.
+
+### `biomeinfo.get_active_v6_biomes()`
+Returns a table containing the names of all v6 biomes that are actively
+used in the current world, e.g. those that have been activated
+by the use of the mapgen v6 flags (`mgv6_spflags`).
+
+### `biomeinfo.all_v6_biomes`
+This is a table containing all v6 biomes (as strings), even those that
+might not be used in the current world.
+
+### v6 biome names
+
+These are the biome names used in this mod:
+
+* Normal
+* Desert
+* Jungle
+* Tundra
+* Taiga

mods/CORE/biomeinfo/README.md

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+# Biome Info API [`biomeinfo`]
+This is an API mod for mod developers to add a couple of missing
+biome-related functions.
+Currently, this mod only adds v6-related functions.
+Most importantly, you can get the heat, humidity and biome in the v6 mapgen.
+
+See `API.md` for the API documentation.
+
+Current version: 1.0.1 (this is a [SemVer](https://semver.org/))
+
+License: MIT License

mods/CORE/biomeinfo/init.lua

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+biomeinfo = {}
+
+-- Copied from mapgen_v6.h
+local MGV6_FREQ_HOT = 0.4
+local MGV6_FREQ_SNOW = -0.4
+local MGV6_FREQ_TAIGA = 0.5
+local MGV6_FREQ_JUNGLE = 0.5
+
+-- Biome types
+local BT_NORMAL = "Normal"
+local BT_TUNDRA = "Tundra"
+local BT_TAIGA = "Taiga"
+local BT_DESERT = "Desert"
+local BT_JUNGLE = "Jungle"
+
+-- Get mapgen settings
+
+local seed = tonumber(minetest.get_mapgen_setting("seed")) or 0
+
+local mgv6_perlin_biome, mgv6_perlin_humidity, mgv6_np_biome
+
+local v6_flags_str = minetest.get_mapgen_setting("mgv6_spflags")
+if v6_flags_str == nil then
+	v6_flags_str = ""
+end
+local v6_flags = string.split(v6_flags_str)
+local v6_use_snow_biomes = true
+local v6_use_jungles = true
+-- TODO: Implement biome blend.
+-- Currently we pretend biome blend is disabled.
+-- This just makes the calculations inaccurate near biome boundaries,
+-- but should be fine otherwise.
+local v6_use_biome_blend = false
+for f=1, #v6_flags do
+	local flag = v6_flags[f]:trim()
+	if flag == "nosnowbiomes" then
+		v6_use_snow_biomes = false
+	end
+	if flag == "snowbiomes" then
+		v6_use_snow_biomes = true
+	end
+	if flag == "nojungles" then
+		v6_use_jungles = false
+	end
+	if flag == "jungles" then
+		v6_use_jungles = true
+	end
+	if flag == "nobiomeblend" then
+		v6_use_biome_blend = false
+	end
+-- TODO
+--	if flag == "biomeblend" then
+--		v6_use_biome_blend = true
+--	end
+end
+-- Force-enable jungles when snowbiomes flag is set
+if v6_use_snow_biomes then
+	v6_use_jungles = true
+end
+local v6_freq_desert = tonumber(minetest.get_mapgen_setting("mgv6_freq_desert") or 0.45)
+
+local NOISE_MAGIC_X = 1619
+local NOISE_MAGIC_Y = 31337
+local NOISE_MAGIC_Z = 52591
+local NOISE_MAGIC_SEED = 1013
+local noise2d = function(x, y, seed)
+	-- TODO: implement noise2d function for biome blend
+	return 0
+--[[
+	local n = (NOISE_MAGIC_X * x + NOISE_MAGIC_Y * y
+	+ NOISE_MAGIC_SEED * seed) & 0x7fffffff;
+	n = (n >> 13) ^ n;
+	n = (n * (n * n * 60493 + 19990303) + 1376312589) & 0x7fffffff;
+	return 1.0 - n / 0x40000000;
+]]
+end
+
+biomeinfo.all_v6_biomes = {
+	BT_NORMAL,
+	BT_DESERT,
+	BT_JUNGLE,
+	BT_TUNDRA,
+	BT_TAIGA
+}
+
+local function init_perlins()
+	if not mgv6_perlin_biome then
+		mgv6_np_biome = minetest.get_mapgen_setting_noiseparams("mgv6_np_biome")
+		if mgv6_np_biome then
+			mgv6_perlin_biome = minetest.get_perlin(mgv6_np_biome)
+		end
+	end
+	if not mgv6_perlin_humidity then
+		local np_humidity = minetest.get_mapgen_setting_noiseparams("mgv6_np_humidity")
+		if np_humidity then
+			mgv6_perlin_humidity = minetest.get_perlin(np_humidity)
+		end
+	end
+end
+
+function biomeinfo.get_active_v6_biomes()
+	local biomes = { BT_NORMAL, BT_DESERT }
+	if v6_use_jungles then
+		table.insert(biomes, BT_JUNGLE)
+	end
+	if v6_use_snow_biomes then
+		table.insert(biomes, BT_TUNDRA)
+		table.insert(biomes, BT_TAIGA)
+	end
+	return biomes
+end
+
+function biomeinfo.get_v6_heat(pos)
+	init_perlins()
+	local bpos = vector.floor(pos)
+	-- The temperature noise needs a special offset (see calculateNoise in mapgen_v6.cpp)
+	return mgv6_perlin_biome:get_2d({x=bpos.x + mgv6_np_biome.spread.x*0.6, y=bpos.z + mgv6_np_biome.spread.z*0.2})
+end
+
+function biomeinfo.get_v6_humidity(pos)
+	init_perlins()
+	local bpos = vector.floor(pos)
+	return mgv6_perlin_humidity:get_2d({x=bpos.x, y=bpos.z})
+end
+
+-- Returns the v6 biome at pos.
+-- Returns a string representing the biome name.
+function biomeinfo.get_v6_biome(pos)
+	init_perlins()
+	local bpos = vector.floor(pos)
+	-- Based on the algorithm MapgenV6::getBiome in mapgen_v6.cpp
+
+	local pos2d = {x=bpos.x, y=bpos.z}
+	if not mgv6_perlin_biome or not mgv6_perlin_humidity then
+		return "???"
+	end
+	local d = biomeinfo.get_v6_heat(bpos)
+	local h = biomeinfo.get_v6_humidity(bpos)
+
+	if (v6_use_snow_biomes) then
+		local blend
+		if v6_use_biome_blend then
+			blend = noise2d(pos2d.x, pos2d.y, seed) / 40
+		else
+			blend = 0
+		end
+
+		if (d > MGV6_FREQ_HOT + blend) then
+			if (h > MGV6_FREQ_JUNGLE + blend) then
+				return BT_JUNGLE
+			end
+			return BT_DESERT
+		end
+		if (d < MGV6_FREQ_SNOW + blend) then
+			if (h > MGV6_FREQ_TAIGA + blend) then
+				return BT_TAIGA
+			end
+			return BT_TUNDRA
+		end
+		return BT_NORMAL
+	end
+
+	if (d > v6_freq_desert) then
+		return BT_DESERT
+	end
+
+	if ((v6_use_biome_blend) and (d > v6_freq_desert - 0.10) and
+			((noise2d(pos2d.x, pos2d.y, seed) + 1.0) > (v6_freq_desert - d) * 20.0)) then
+		return BT_DESERT
+	end
+
+	if ((v6_use_jungles) and (h > 0.75)) then
+		return BT_JUNGLE
+	end
+
+	return BT_NORMAL
+end
+
+

mods/CORE/biomeinfo/mod.conf

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+name = biomeinfo
+description = Simple API to get data about biomes.