206 lines
6.9 KiB
Lua
206 lines
6.9 KiB
Lua
local modpath = minetest.get_modpath(minetest.get_current_modname()) .. '/'
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local mod_data_path = modpath .. 'river_data/'
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if not io.open(mod_data_path .. 'size', 'r') then
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mod_data_path = modpath .. 'demo_data/'
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end
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local world_data_path = minetest.get_worldpath() .. '/river_data/'
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minetest.mkdir(world_data_path)
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local load_map = dofile(modpath .. 'load.lua')
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local function copy_if_needed(filename)
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local wfilename = world_data_path..filename
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local wfile = io.open(wfilename, 'rb')
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if wfile then
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wfile:close()
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return
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end
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local mfilename = mod_data_path..filename
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local mfile = io.open(mfilename, 'rb')
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local wfile = io.open(wfilename, 'wb')
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wfile:write(mfile:read("*all"))
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mfile:close()
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wfile:close()
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end
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copy_if_needed('size')
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local sfile = io.open(world_data_path..'size', 'r')
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local X = tonumber(sfile:read('*l'))
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local Z = tonumber(sfile:read('*l'))
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sfile:close()
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copy_if_needed('dem')
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local dem = load_map('dem', 2, true, X*Z)
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copy_if_needed('lakes')
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local lakes = load_map('lakes', 2, true, X*Z)
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copy_if_needed('dirs')
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local dirs = load_map('dirs', 1, false, X*Z)
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copy_if_needed('rivers')
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local rivers = load_map('rivers', 4, false, X*Z)
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copy_if_needed('offset_x')
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local offset_x = load_map('offset_x', 1, true, X*Z)
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for k, v in ipairs(offset_x) do
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offset_x[k] = (v+0.5)/256
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end
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copy_if_needed('offset_y')
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local offset_z = load_map('offset_y', 1, true, X*Z)
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for k, v in ipairs(offset_z) do
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offset_z[k] = (v+0.5)/256
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end
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-- To index a flat array representing a 2D map
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local function index(x, z)
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return z*X+x+1
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end
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local blocksize = mapgen_rivers.blocksize
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local min_catchment = mapgen_rivers.min_catchment
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local max_catchment = mapgen_rivers.max_catchment
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-- Width coefficients: coefficients solving
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-- wfactor * min_catchment ^ wpower = 1/(2*blocksize)
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-- wfactor * max_catchment ^ wpower = 1
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local wpower = math.log(2*blocksize)/math.log(max_catchment/min_catchment)
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local wfactor = 1 / max_catchment ^ wpower
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local function river_width(flow)
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flow = math.abs(flow)
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if flow < min_catchment then
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return 0
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end
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return math.min(wfactor * flow ^ wpower, 1)
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end
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local noise_heat -- Need a large-scale noise here so no heat blend
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local elevation_chill = mapgen_rivers.elevation_chill
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local function get_temperature(x, y, z)
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local pos = {x=x, y=z}
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return noise_heat:get2d(pos) - y*elevation_chill
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end
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local glaciers = mapgen_rivers.glaciers
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local glacier_factor = mapgen_rivers.glacier_factor
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local init = false
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-- On map generation, determine into which polygon every point (in 2D) will fall.
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-- Also store polygon-specific data
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local function make_polygons(minp, maxp)
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if not init then
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if glaciers then
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noise_heat = minetest.get_perlin(mapgen_rivers.noise_params.heat)
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end
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init = true
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end
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local chulens = maxp.x - minp.x + 1
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local polygons = {}
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-- Determine the minimum and maximum coordinates of the polygons that could be on the chunk, knowing that they have an average size of 'blocksize' and a maximal offset of 0.5 blocksize.
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local xpmin, xpmax = math.max(math.floor(minp.x/blocksize - 0.5), 0), math.min(math.ceil(maxp.x/blocksize), X-2)
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local zpmin, zpmax = math.max(math.floor(minp.z/blocksize - 0.5), 0), math.min(math.ceil(maxp.z/blocksize), Z-2)
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-- Iterate over the polygons
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for xp = xpmin, xpmax do
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for zp=zpmin, zpmax do
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local iA = index(xp, zp)
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local iB = index(xp+1, zp)
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local iC = index(xp+1, zp+1)
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local iD = index(xp, zp+1)
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-- Extract the vertices of the polygon
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local poly_x = {offset_x[iA]+xp, offset_x[iB]+xp+1, offset_x[iC]+xp+1, offset_x[iD]+xp}
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local poly_z = {offset_z[iA]+zp, offset_z[iB]+zp, offset_z[iC]+zp+1, offset_z[iD]+zp+1}
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local polygon = {x=poly_x, z=poly_z, i={iA, iB, iC, iD}}
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local bounds = {} -- Will be a list of the intercepts of polygon edges for every Z position (scanline algorithm)
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-- Calculate the min and max Z positions
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local zmin = math.max(math.floor(blocksize*math.min(unpack(poly_z)))+1, minp.z)
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local zmax = math.min(math.floor(blocksize*math.max(unpack(poly_z))), maxp.z)
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-- And initialize the arrays
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for z=zmin, zmax do
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bounds[z] = {}
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end
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local i1 = 4
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for i2=1, 4 do -- Loop on 4 edges
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local z1, z2 = poly_z[i1], poly_z[i2]
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-- Calculate the integer Z positions over which this edge spans
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local lzmin = math.floor(blocksize*math.min(z1, z2))+1
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local lzmax = math.floor(blocksize*math.max(z1, z2))
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if lzmin <= lzmax then -- If there is at least one position in it
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local x1, x2 = poly_x[i1], poly_x[i2]
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-- Calculate coefficient of the equation defining the edge: X=aZ+b
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local a = (x1-x2) / (z1-z2)
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local b = blocksize*(x1 - a*z1)
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for z=math.max(lzmin, minp.z), math.min(lzmax, maxp.z) do
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-- For every Z position involved, add the intercepted X position in the table
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table.insert(bounds[z], a*z+b)
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end
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end
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i1 = i2
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end
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for z=zmin, zmax do
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-- Now sort the bounds list
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local zlist = bounds[z]
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table.sort(zlist)
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local c = math.floor(#zlist/2)
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for l=1, c do
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-- Take pairs of X coordinates: all positions between them belong to the polygon.
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local xmin = math.max(math.floor(zlist[l*2-1])+1, minp.x)
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local xmax = math.min(math.floor(zlist[l*2]), maxp.x)
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local i = (z-minp.z) * chulens + (xmin-minp.x) + 1
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for x=xmin, xmax do
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-- Fill the map at these places
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polygons[i] = polygon
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i = i + 1
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end
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end
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end
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local poly_dem = {dem[iA], dem[iB], dem[iC], dem[iD]}
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polygon.dem = poly_dem
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polygon.lake = math.min(lakes[iA], lakes[iB], lakes[iC], lakes[iD])
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-- Now, rivers.
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-- Load river flux values for the 4 corners
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local riverA = river_width(rivers[iA])
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local riverB = river_width(rivers[iB])
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local riverC = river_width(rivers[iC])
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local riverD = river_width(rivers[iD])
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if glaciers then -- Widen the river
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if get_temperature(poly_x[1]*blocksize, poly_dem[1], poly_z[1]*blocksize) < 0 then
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riverA = math.min(riverA*glacier_factor, 1)
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end
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if get_temperature(poly_x[2]*blocksize, poly_dem[2], poly_z[2]*blocksize) < 0 then
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riverB = math.min(riverB*glacier_factor, 1)
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end
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if get_temperature(poly_x[3]*blocksize, poly_dem[3], poly_z[3]*blocksize) < 0 then
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riverC = math.min(riverC*glacier_factor, 1)
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end
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if get_temperature(poly_x[4]*blocksize, poly_dem[4], poly_z[4]*blocksize) < 0 then
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riverD = math.min(riverD*glacier_factor, 1)
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end
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end
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polygon.river_corners = {riverA, 1-riverB, 2-riverC, 1-riverD}
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-- Flow directions
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local dirA, dirB, dirC, dirD = dirs[iA], dirs[iB], dirs[iC], dirs[iD]
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-- Determine the river flux on the edges, by testing dirs values
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local river_west = (dirA==1 and riverA or 0) + (dirD==3 and riverD or 0)
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local river_north = (dirA==2 and riverA or 0) + (dirB==4 and riverB or 0)
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local river_east = 1 - (dirB==1 and riverB or 0) - (dirC==3 and riverC or 0)
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local river_south = 1 - (dirD==2 and riverD or 0) - (dirC==4 and riverC or 0)
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polygon.rivers = {river_west, river_north, river_east, river_south}
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end
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end
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return polygons
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end
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return make_polygons
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