--[[ Nether mod portal examples for Minetest These portal API examples work independently of the Nether realm and Nether portal. To try these examples, enable them in: Minetest -> Settings -> All settings -> Mods -> nether Once enabled, details on how to build them can be found in dungeon chests in the book of portals. -- Copyright (C) 2020 Treer Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted, provided that the above copyright notice and this permission notice appear in all copies. THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. ]]-- local S = nether.get_translator local ENABLE_PORTAL_EXAMPLE_FLOATLANDS = false local ENABLE_PORTAL_EXAMPLE_SURFACETRAVEL = false -- Sets how far a Surface Portal will travel, measured in cells along the Moore curve, -- which are about 117 nodes square each. Larger numbers will generally mean further distance -- as-the-crow-flies, but this will not always be true due to the how the Moore curve -- frequently doubles back upon itself. -- This doubling-back prevents the surface portal from taking players easily accross the -- map - the curve is 262144 cells long! local SURFACE_TRAVEL_DISTANCE = 26 --=================================================-- -- Portal to the Floatlands, playable code example -- --==================================================-- local FLOATLANDS_ENABLED local FLOATLAND_LEVEL = 1280 if minetest.settings:get_bool("nether_enable_portal_example_floatlands", ENABLE_PORTAL_EXAMPLE_FLOATLANDS) or ENABLE_PORTAL_EXAMPLE_FLOATLANDS then local floatlands_flavortext = "" if minetest.get_mapgen_setting("mg_name") == "v7" then local mgv7_spflags = minetest.get_mapgen_setting("mgv7_spflags") FLOATLANDS_ENABLED = mgv7_spflags ~= nil and mgv7_spflags:find("floatlands") ~= nil and mgv7_spflags:find("nofloatlands") == nil FLOATLAND_LEVEL = minetest.get_mapgen_setting("mgv7_floatland_level") or 1280 if FLOATLANDS_ENABLED then floatlands_flavortext = "\n\n " .. S("There is a floating land of hills and forests up there, over the edges of which is a perilous drop all the way back down to sea level. We have not found how far these pristine lands extend. I have half a mind to retire there one day.") end end nether.register_portal("floatlands_portal", { shape = nether.PortalShape_Platform, frame_node_name = "default:ice", wormhole_node_color = 7, -- 7 is white particle_texture = { name = "nether_particle_anim1.png", animation = { type = "vertical_frames", aspect_w = 7, aspect_h = 7, length = 1, }, scale = 1.5 }, title = S("Floatlands Portal"), book_of_portals_pagetext = S([[Requiring 21 blocks of ice, and constructed in the shape of a 3 × 3 platform with walls, or like a bowl. A finished platform is 2 blocks high, and 5 blocks wide at the widest in both directions. This portal is different to the others, rather than acting akin to a doorway it appears to the eye more like a small pool of water which can be stepped into. Upon setting foot in the portal we found ourselves at a tremendous altitude.@1]], floatlands_flavortext), is_within_realm = function(pos) -- return true if pos is inside the Nether return pos.y > FLOATLAND_LEVEL - 200 end, find_realm_anchorPos = function(surface_anchorPos, player_name) -- TODO: Once paramat finishes adjusting the floatlands, implement a surface algorithm that finds land local destination_pos = {x = surface_anchorPos.x ,y = FLOATLAND_LEVEL + 2, z = surface_anchorPos.z} -- a y_factor of 0 makes the search ignore the altitude of the portals (as long as they are in the Floatlands) local existing_portal_location, existing_portal_orientation = nether.find_nearest_working_portal("floatlands_portal", destination_pos, 10, 0) if existing_portal_location ~= nil then return existing_portal_location, existing_portal_orientation else return destination_pos end end }) end --==============================================-- -- Surface-travel portal, playable code example -- --==============================================-- -- These Moore Curve functions required by surface_portal's find_surface_anchorPos() will -- be assigned later in this file. local get_moore_distance -- will be function get_moore_distance(cell_count, x, y): integer local get_moore_coords -- will be function get_moore_coords(cell_count, distance): pos2d if minetest.settings:get_bool("nether_enable_portal_example_surfacetravel", ENABLE_PORTAL_EXAMPLE_SURFACETRAVEL) or ENABLE_PORTAL_EXAMPLE_SURFACETRAVEL then nether.register_portal("surface_portal", { shape = nether.PortalShape_Circular, frame_node_name = "default:tinblock", wormhole_node_name = "nether:portal_alt", wormhole_node_color = 4, -- 4 is cyan title = S("Surface Portal"), book_of_portals_pagetext = S([[Requiring 16 blocks of tin and constructed in a circular fashion, a finished frame is seven blocks wide, seven blocks high, and stands vertically like a doorway. These travel a distance along the ground, and even when constructed deep underground will link back up to the surface. They appear to favor a strange direction, with the exit portal linking back only for as long as the portal stays open — attempting to reopen a portal from the exit doorway leads to a new destination along this favored direction. It has stymied our ability to study the behavior of these portals because without constructing dual portals and keeping both open it's hard to step through more than one and still be able to return home. Due to such difficulties, we never learned what determines the direction and distance where the matching twin portal will appear, and I have lost my friend and protégé. In cavalier youth and with little more than a rucksack, Coudreau has decided to follow the chain as far as it goes, and has not been seen since. Coudreau believes it works in epicycles, but I am not convinced. Still, I cling to the hope that one day the portal will open and Coudreau will step out from whichever place leads to this one, perhaps with an epic tale to tell.]]), is_within_realm = function(pos) -- Always return true, because these portals always just take you around the surface -- rather than taking you to a different realm return true end, find_realm_anchorPos = function(surface_anchorPos, player_name) -- This function isn't needed, since this type of portal always goes to the surface minetest.log("error" , "find_realm_anchorPos called for surface portal") return {x=0, y=0, z=0} end, find_surface_anchorPos = function(realm_anchorPos, player_name) -- A portal definition doesn't normally need to provide a find_surface_anchorPos() function, -- since find_surface_target_y() will be used by default, but these portals travel around the -- surface (following a Moore curve) so will be calculating a different x and z to realm_anchorPos. local cellCount = 512 local maxDistFromOrigin = 30000 -- the world edges are at X=30927, X=−30912, Z=30927 and Z=−30912 -- clip realm_anchorPos to maxDistFromOrigin, and move the origin so that all values are positive local x = math.min(maxDistFromOrigin, math.max(-maxDistFromOrigin, realm_anchorPos.x)) + maxDistFromOrigin local z = math.min(maxDistFromOrigin, math.max(-maxDistFromOrigin, realm_anchorPos.z)) + maxDistFromOrigin local divisor = math.ceil(maxDistFromOrigin * 2 / cellCount) local distance = get_moore_distance(cellCount, math.floor(x / divisor + 0.5), math.floor(z / divisor + 0.5)) local destination_distance = (distance + SURFACE_TRAVEL_DISTANCE) % (cellCount * cellCount) local moore_pos = get_moore_coords(cellCount, destination_distance) local target_x = moore_pos.x * divisor - maxDistFromOrigin local target_z = moore_pos.y * divisor - maxDistFromOrigin local search_radius = divisor / 2 - 5 -- any portal within this area will do -- a y_factor of 0 makes the search ignore the altitude of the portals local existing_portal_location, existing_portal_orientation = nether.find_nearest_working_portal("surface_portal", {x = target_x, y = 0, z = target_z}, search_radius, 0) if existing_portal_location ~= nil then -- use the existing portal that was found near target_x, target_z return existing_portal_location, existing_portal_orientation else -- find a good location for the new portal, or if that isn't possible then at -- least adjust the coords a little so portals don't line up in a grid local adj_x, adj_z = 0, 0 -- Deterministically look for a location in the cell where get_spawn_level() can give -- us a surface height, since nether.find_surface_target_y() works *much* better when -- it can use get_spawn_level() local prng = PcgRandom( -- seed the prng so that all portals for these Moore Curve coords will use the same random location moore_pos.x * 65732 + moore_pos.y * 729 + minetest.get_mapgen_setting("seed") * 3 ) local attemptLimit = 15 -- how many attempts we'll make at finding a good location for attempt = 1, attemptLimit do adj_x = math.floor(prng:rand_normal_dist(-search_radius, search_radius, 2) + 0.5) adj_z = math.floor(prng:rand_normal_dist(-search_radius, search_radius, 2) + 0.5) if minetest.get_spawn_level == nil or minetest.get_spawn_level(target_x + adj_x, target_z + adj_z) ~= nil then -- Found a location which will be at ground level - unless a player has built there. -- Or this is MT 0.4 which does not have get_spawn_level(), so there's no point looking -- at any further further random locations. break end end local destination_pos = {x = target_x + adj_x, y = 0, z = target_z + adj_z} destination_pos.y = nether.find_surface_target_y(destination_pos.x, destination_pos.z, "surface_portal", player_name) return destination_pos end end }) end --=========================================-- -- Hilbert curve and Moore curve functions -- --=========================================-- -- These are space-filling curves, used by the surface_portal example as a way to determine where -- to place portals. https://en.wikipedia.org/wiki/Moore_curve -- Flip a quadrant on a diagonal axis -- cell_count is the number of cells across the square is split into, and must be a power of 2 -- if flip_twice is true then pos does not change (even numbers of flips cancel out) -- if flip_direction is true then the position is flipped along the \ diagonal -- if flip_direction is false then the position is flipped along the / diagonal local function hilbert_flip(cell_count, pos, flip_direction, flip_twice) if not flip_twice then if flip_direction then pos.x = (cell_count - 1) - pos.x; pos.y = (cell_count - 1) - pos.y; end local temp_x = pos.x; pos.x = pos.y; pos.y = temp_x; end end local function test_bit(cell_count, value, flag) local bit_value = cell_count / 2 while bit_value > flag and bit_value >= 1 do if value >= bit_value then value = value - bit_value end bit_value = bit_value / 2 end return value >= bit_value end -- Converts (x,y) to distance -- starts at bottom left corner, i.e. (0, 0) -- ends at bottom right corner, i.e. (cell_count - 1, 0) local function get_hilbert_distance (cell_count, x, y) local distance = 0 local pos = {x=x, y=y} local rx, ry local s = cell_count / 2 while s > 0 do if test_bit(cell_count, pos.x, s) then rx = 1 else rx = 0 end if test_bit(cell_count, pos.y, s) then ry = 1 else ry = 0 end local rx_XOR_ry = rx if ry == 1 then rx_XOR_ry = 1 - rx_XOR_ry end -- XOR'd ry against rx distance = distance + s * s * (2 * rx + rx_XOR_ry) hilbert_flip(cell_count, pos, rx > 0, ry > 0); s = math.floor(s / 2) end return distance; end -- Converts distance to (x,y) local function get_hilbert_coords(cell_count, distance) local pos = {x=0, y=0} local rx, ry local s = 1 while s < cell_count do rx = math.floor(distance / 2) % 2 ry = distance % 2 if rx == 1 then ry = 1 - ry end -- XOR ry with rx hilbert_flip(s, pos, rx > 0, ry > 0); pos.x = pos.x + s * rx pos.y = pos.y + s * ry distance = math.floor(distance / 4) s = s * 2 end return pos end -- Converts (x,y) to distance -- A Moore curve is a variation of the Hilbert curve that has the start and -- end next to each other. -- Top middle point is the start/end location get_moore_distance = function(cell_count, x, y) local quadLength = cell_count / 2 local quadrant = 1 - math.floor(y / quadLength) if math.floor(x / quadLength) == 1 then quadrant = 3 - quadrant end local flipDirection = x < quadLength local pos = {x = x % quadLength, y = y % quadLength} hilbert_flip(quadLength, pos, flipDirection, false) return (quadrant * quadLength * quadLength) + get_hilbert_distance(quadLength, pos.x, pos.y) end -- Converts distance to (x,y) -- A Moore curve is a variation of the Hilbert curve that has the start and -- end next to each other. -- Top middle point is the start/end location get_moore_coords = function(cell_count, distance) local quadLength = cell_count / 2 local quadDistance = quadLength * quadLength local quadrant = math.floor(distance / quadDistance) local flipDirection = distance * 2 < cell_count * cell_count local pos = get_hilbert_coords(quadLength, distance % quadDistance) hilbert_flip(quadLength, pos, flipDirection, false) if quadrant >= 2 then pos.x = pos.x + quadLength end if quadrant % 3 == 0 then pos.y = pos.y + quadLength end return pos end