Add peoplecantblur

peoplecantblur/README.txt

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+ People can't blur
+===================
+Uses the blur function to flatten areas with the chatcommand `/flat`
+
+Depends: default
+
+ Licenses
+----------
+
+Source code:
+	WTFPL (created by Krock)

peoplecantblur/depends.txt

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+default

peoplecantblur/init.lua

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+-- peoplecantblur - Generate flat areas
+
+local HEIGHT_CHECK = 20
+local c_air = minetest.get_content_id("air")
+
+
+-- Function to get the node definition groups to check for a surface node
+local function check_surface_content(c_id, cache_c)
+	if cache_c[c_id] ~= nil then
+		return cache_c[c_id]
+	end
+
+	-- Not contain in the table yet
+	local name = minetest.get_name_from_content_id(c_id)
+	local def = minetest.registered_nodes[name]
+	if def and def.groups then
+		local is_surface_content = def.groups.soil or def.groups.sand or def.groups.stone
+		cache_c[c_id] = (is_surface_content ~= nil)
+		return is_surface_content
+	end
+
+	-- Fallback for unknown nodes
+	return false
+end
+
+-- Find the ground of a coordinate
+local function get_ground(data, area, pos, max_height, cache_c, get_contents)
+	local id_cache = {}
+	local rel_surface -- Relative height of surface
+
+	-- Find the ground height (check downwards)
+	for y = 0, -max_height, -1 do
+		local c_id = data[area:index(pos.x, pos.y + y, pos.z)]
+		local is_surface_content = check_surface_content(c_id, cache_c)
+		id_cache[y] = { c_id, is_surface_content }
+
+		if is_surface_content then
+			if y ~= 0 then
+				rel_surface = y
+			end
+			break
+		end
+	end
+
+	if not rel_surface then
+		-- Check upper area
+		for y = 1, max_height do
+			local c_id = data[area:index(pos.x, pos.y + y, pos.z)]
+			local is_surface_content = check_surface_content(c_id, cache_c)
+			id_cache[y] = { c_id, is_surface_content }
+
+			if not is_surface_content then
+				rel_surface = y - 1
+				break
+			end
+		end
+	end
+
+	if not rel_surface then
+		-- Can not find ground in the air
+		return {}
+	end
+
+	if not get_contents then
+		return { rel_surface = rel_surface }
+	end
+
+	-- Get the ground contents
+	local c_contents = {}
+	local c_last_good = id_cache[rel_surface][1]
+
+	for y = rel_surface, rel_surface - 4, -1 do
+		local c_data = id_cache[y] -- { c_id, is_surface_content }
+		if not c_data then
+			local c_id = data[area:index(pos.x, pos.y + y, pos.z)]
+			local is_surface_content = check_surface_content(c_id, cache_c)
+			c_data = { c_id, is_surface_content }
+		end
+
+		-- insert: (is_surface_content) ? c_id : c_last_good
+		table.insert(c_contents, c_data[2] and c_data[1] or c_last_good)
+
+		if c_data[2] then
+			c_last_good = c_data[1]
+		end
+	end
+
+	return {
+		rel_surface = rel_surface,
+		c_contents = c_contents
+	}
+end
+
+local function flatten(ppos, radius)
+	-- Flattened area is within radius, we need one more to use the blur function
+	local minp = vector.add(ppos, -radius - 1)
+	local maxp = vector.add(ppos, radius + 1)
+	-- Required to check the ground properly
+	minp.y = minp.y - HEIGHT_CHECK
+	maxp.y = maxp.y + HEIGHT_CHECK
+	local max_height = radius + HEIGHT_CHECK
+
+	local heightmap = {}
+
+	local vm = minetest.get_voxel_manip()
+	local emin, emax = vm:read_from_map(minp, maxp)
+	local area = VoxelArea:new{MinEdge=emin, MaxEdge=emax}
+	local data = vm:get_data()
+
+	-- Lookup table for content ID groups
+	local cache_c = {}
+
+	for z = minp.z, maxp.z do
+	for x = minp.x, maxp.x do
+		local ground = get_ground(
+				data,
+				area,
+				vector.new(x, ppos.y, z),
+				max_height,
+				cache_c,
+				math.abs(x - ppos.x) <= radius and math.abs(z - ppos.z) <= radius
+		)
+		heightmap[z * 0x10000 + x] = ground
+	end
+	end
+
+	-- Get the relative height from the heightmap with relative coordinates
+	local get_height = function(map, x, z, fallback)
+		local info = map[math.floor(z + 0.5) * 0x10000 + math.floor(x + 0.5)]
+		if info and info.rel_surface then
+			return info.rel_surface
+		end
+		return fallback
+	end
+
+	local fallback_y = get_height(heightmap, ppos.x, ppos.z)
+	if not fallback_y then
+		minetest.log("warning", "Could not find the relative fallback height. Reset to 0")
+		fallback_y = 0
+	end
+
+	local _dirty_ = false
+	local E = 1 -- effect width
+
+	-- Apply blur filter on each position and update the nodes
+	for z = minp.z + 1, maxp.z - 1 do
+	for x = minp.x + 1, maxp.x - 1 do
+		--[[
+			+----+----+----+
+			|  1 |  2 |  1 |   4
+			|  2 |  4 |  2 |   8
+			|  1 |  2 |  1 |   4
+			+----+----+----+   -> 16
+		]]
+		local old_h = get_height(heightmap, x, z, fallback_y)
+		local h = old_h * 4 + (
+			  get_height(heightmap, x    , z - E, fallback_y)
+			+ get_height(heightmap, x - E, z    , fallback_y)
+			+ get_height(heightmap, x + E, z    , fallback_y)
+			+ get_height(heightmap, x    , z + E, fallback_y)
+		) * 2 + (
+			  get_height(heightmap, x - E, z - E, fallback_y)
+			+ get_height(heightmap, x + E, z - E, fallback_y)
+			+ get_height(heightmap, x - E, z + E, fallback_y)
+			+ get_height(heightmap, x + E, z + E, fallback_y)
+		)
+
+		h = math.floor(h / 16 + 0.5)
+		if h ~= old_h then
+			-- Height changed -> Change terrain
+			local nodes = heightmap[z * 0x10000 + x].c_contents
+
+			local max_y = math.max(h, old_h) + 1
+			local min_y = math.min(h, old_h) - 3
+			local i = 1
+			for y = max_y, min_y, -1 do
+				local vi = area:index(x, ppos.y + y, z)
+				if y > h then
+					data[vi] = c_air
+				else
+					data[vi] = nodes[math.min(#nodes, i)]
+					i = i + 1
+				end
+				_dirty_ = true
+			end
+		end
+	end
+	end
+
+	if not _dirty_ then
+		return
+	end
+	vm:set_data(data)
+	vm:calc_lighting()
+	vm:write_to_map(data)
+	vm:update_map()
+end
+
+
+minetest.register_chatcommand("flat", {
+	description = "Makes the area around you flatter.",
+	privs = {server = true},
+	func = function(name, param)
+		local player = minetest.get_player_by_name(name)
+		local player_pos = vector.round(player:getpos())
+		-- Flatten an area of (2 * 4 + 1) ^ 2 nodes
+		flatten(player_pos, 4)
+		return true, "OK."
+	end
+})