initial

LICENSE.txt

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+MIT License
+
+Copyright (c) 2021 FaceDeer
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.txt

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+Adds deep underground chasms to the world.
+
+Copied from:
+https://github.com/FaceDeer/dfcaverns/tree/master/chasms

init.lua

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+local data = {}
+
+chasms = {}
+
+local ignore = {}
+
+-- Use this to set node types to be left alone by chasm-carving
+chasms.register_ignore = function(node_name)
+	ignore[minetest.get_content_id(node_name)] = true
+end
+
+chasms.ignore_content_id = function(content_id)
+	return ignore[content_id]
+end
+
+local maxy = tonumber(minetest.settings:get("chasms_maxy")) or -50
+local miny = tonumber(minetest.settings:get("chasms_miny")) or -2500
+local falloff = tonumber(minetest.settings:get("chasms_falloff")) or 100
+
+local chasms_threshold = tonumber(minetest.settings:get("chasms_threshold")) or 0.9
+local np_chasms_default = {
+	offset = 0,
+	scale = 1,
+	spread = {x = 50, y = 1000, z = 3000},
+	seed = 94586,
+	octaves = 2,
+	persist = 0.63,
+	lacunarity = 2.0,
+}
+local np_chasms = minetest.settings:get_np_group("chasms_params") or np_chasms_default
+
+local nobj_chasm
+local chasm_data = {}
+
+local waver_strength = 8
+local waver_vector = {x=waver_strength, y=0, z=0}
+local np_waver = {
+	offset = 0,
+	scale = waver_strength,
+	spread = {x = 50, y = 50, z = 50},
+	seed = 49585,
+	octaves = 2,
+	persist = 0.63,
+	lacunarity = 2.0,
+}
+local nobj_waver
+local waver_data = {}
+
+local minfalloff = miny + falloff
+local maxfalloff = maxy - falloff
+local get_intensity = function(y)
+	if y < miny or y > maxy then
+		return 0
+	end
+	if y <= maxfalloff and y >= minfalloff then
+		return 1
+	end
+	if y < minfalloff then
+		return (y-miny)/falloff
+	end
+--	if y > maxfalloff then
+	return (maxy-y)/falloff
+--	end
+end
+
+local c_air = minetest.get_content_id("air")
+
+local log_location
+if mapgen_helper.log_location_enabled then
+	log_location = mapgen_helper.log_first_location
+end
+
+minetest.register_on_generated(function(minp, maxp, seed)
+	if minp.y >= maxy or maxp.y <= miny then
+		return
+	end
+	
+	local vm, emin, emax = minetest.get_mapgen_object("voxelmanip")
+	vm:get_data(data)
+
+	nobj_chasm = nobj_chasm or minetest.get_perlin_map(np_chasms, {x = emax.x - emin.x + 1 + waver_strength*2, y = emax.y - emin.y + 1, z = emax.z - emin.z + 1})
+	nobj_chasm:get_3d_map_flat(vector.subtract(emin, waver_vector), chasm_data)
+
+	nobj_waver = nobj_waver or minetest.get_perlin_map(np_waver, {x = emax.x - emin.x + 1, y = emax.y - emin.y + 1, z = emax.z - emin.z + 1})
+	nobj_waver:get_3d_map_flat(emin, waver_data)
+
+	local chasm_area = VoxelArea:new{MinEdge = vector.subtract(emin, waver_vector), MaxEdge = vector.add(emax, waver_vector)}
+	local data_area = VoxelArea:new{MinEdge = emin, MaxEdge = emax}
+
+	for i, x, y, z in data_area:iterp_xyz(emin, emax) do
+		local waver = math.min(math.max(math.floor(waver_data[i]+0.5), -waver_strength), waver_strength)
+		local intensity = get_intensity(y)
+		if chasm_data[chasm_area:index(x+waver, y, z)]*intensity > chasms_threshold then
+			if not ignore[data[i]] then
+				data[i] = c_air
+				if log_location then log_location("chasm", vector.new(x,y,z)) end
+			end
+		end
+	end
+	
+	vm:set_data(data)
+	vm:calc_lighting()
+	vm:write_to_map()
+end)
+
+local nobj_local_chasm = minetest.get_perlin(np_chasms)
+local nobj_local_waver = minetest.get_perlin(np_waver)
+
+chasms.is_in_chasm = function(pos)
+	nobj_local_chasm = nobj_local_chasm or minetest.get_perlin(np_chasms)
+	nobj_local_waver = nobj_local_waver or minetest.get_perlin(np_waver)
+	local waver = math.min(math.max(math.floor(nobj_local_waver:get_3d(pos)+0.5), -waver_strength), waver_strength)
+	local chasm_value = nobj_local_chasm:get_3d({x=pos.x+waver, y=pos.y, z=pos.z})
+	return chasm_value*get_intensity(pos.y) > chasms_threshold
+end
+
+-- A little cheaper to run, for mapgens that know they don't have to worry about the tops and bottoms of chasms
+chasms.is_in_chasm_without_taper = function(pos)
+	nobj_local_chasm = nobj_local_chasm or minetest.get_perlin(np_chasms)
+	nobj_local_waver = nobj_local_waver or minetest.get_perlin(np_waver)
+	local waver = math.min(math.max(math.floor(nobj_local_waver:get_3d(pos)+0.5), -waver_strength), waver_strength)
+	local chasm_value = nobj_local_chasm:get_3d({x=pos.x+waver, y=pos.y, z=pos.z})
+	return chasm_value > chasms_threshold
+end

mod.conf

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+name=chasms
+depends=mapgen_helper

settingtypes.txt

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+chasms_params (Noise params for chasms) noise_params_3d 0, 1, (50, 1000, 3000), 94586, 2, 0.63, 2.0
+chasms_threshold (Noise threshold for chasms) float 0.9
+chasms_maxy (Maximum Y) int -50
+chasms_miny (Minimum Y) int -2500
+chasms_falloff (Taper range when approaching max or min) int 100