if not modules then modules = { } end modules ['m-openstreetmap'] = {
    version   = 1.001,
    comment   = "companion to m-openstreetmap.mkxl",
    author    = "Hans Hagen, PRAGMA-ADE, Hasselt NL",
    copyright = "PRAGMA ADE / ConTeXt Development Team",
    license   = "see context related readme files"
}

local sin, cos, floor, ceil = math.sin, math.cos, math.floor, math.ceil
local formatters = string.formatters
local concat, tohash, sortedhash, setmetatableindex, insert = table.concat, table.tohash, table.sortedhash, table.setmetatableindex, table.insert
local xmlcollected, xmlparent, xmlfirst, xmlfilter = xml.collected, xml.parent, xml.first, xml.filter
local P, S, Cs, lpegmatch = lpeg.P, lpeg.S, lpeg, lpeg.match

local openstreetmap      = { }
moduledata.openstreetmap = openstreetmap

local report = logs.reporter("openstreetmap")

-- At one of the bachotex meetings Mojca and I sat down to render the bachotek camp site
-- as available in openstreetmap. Of course that was a limited setup and after figuring
-- out some details it went well. Of course we used metapost.
--
-- Years later in 2021 on the mailing list there was some discussion on country outlines
-- and disappointed by the quality of what was referred to I remembered the openstreetmap
-- adventure. I found that I could export my hometown from the web page so I started from
-- that: just stepwise seeing what 'ways' passed and assigning them colors. Just as with
-- the bachotex drawing.
--
-- Then I went searching for what tags actually were available and ran into:
--
-- https://github.com/openstreetmap/osm2pgsql/blob/master/docs/lua.md
--
-- I'm not sure where the script is used, and there are dead links on these pages but some
-- information can be found in that file so I could combine our findings with these. There
-- is a whole infrastructure out there with impressive machinery, style sheet generation
-- etc. but we don't need that here. Also, we don't need to play routes.
--
-- Colors are one thing (not too hard with a k/v mapping), but a nest hurdle is to decide
-- what is a polygon. Actually I found that just checking on something being closed is
-- rather ok. There are a few extra ones. But we can also use the list in the file mentioned.
-- We probably need to check it occasionally with the original, although it looks quite
-- stable.

local polygons = tohash {
    "abandoned:aeroway", "abandoned:amenity", "abandoned:building",
    "abandoned:landuse", "abandoned:power", "aeroway", "allotments",
    "amenity", "area:highway", "craft", "building", "building:part", "club",
    "golf", "emergency", "harbour", "healthcare", "historic", "landuse",
    "leisure", "man_made", "military", "natural", "office", "place", "power",
    "public_transport", "shop", "tourism", "water", "waterway", "wetland",

 -- "bridge",
}

-- The amenity tag is sort of overloading the main tag so we put it in the main
-- hash. This might change.
--
-- The stacking order is important and we just started with processing the tags
-- in a certain order. However, in \LUAMETATEX\ we can now use stacking so that
-- makes for a nice test. At the cost of a bit more metapost code and conversion
-- time we can use that. Anyway, this is the list we use and it's an adaption
-- from the bachitex one.

local order = {
    "landuse",
    "leisure",
    "natural",
 -- "geological",

    "water",
    "amenity",
    "building",
    "barrier",
    "man_made",
    "bridge",

    "historic",
    "military",

 -- "office",
 -- "craft",

 -- "emergency",
 -- "healthcare",
 -- "place",
 -- "power",
 -- "shop",
 -- "sport",
 -- "telecom",

 -- "publictransport",

    "waterway",
    "highway",
    "railway",
    "aeroway",
    "aerialway",

 -- "tourism",
    "boundary", -- overlaps ! not okay for hasselt.osm
 -- "route",
}

-- From the mentioned lua file we get the stacking (funny numbers are used):

-- In Hasselt we have a combination, highway should win :
--
--  <tag k="bridge" v="yes"/>
--  <tag k="highway" v="footway"/>

local stacking = {
    highway = {
        motorway       = 180,
        trunk          = 170,
        primary        = 160,
        secondary      = 150,
        tertiary       = 140,
        residential    = 130,
        unclassified   = 130,
        road           = 130,
        living_street  = 120,
        pedestrian     = 110,
        raceway        = 100,
        motorway_link  = 140,
        trunk_link     = 130,
        primary_link   = 120,
        secondary_link = 110,
        tertiary_link  = 100,
        service        = 150,
        track          = 110,
        path           = 100,
        footway        = 100,
        bridleway      = 100,
        cycleway       = 100,
        steps          = 190,
        platform       = 190,
    },
    railway = {
        rail           = 140,
        subway         = 120,
        narrow_gauge   = 120,
        light_rail     = 120,
        funicular      = 120,
        preserved      = 120,
        monorail       = 120,
        miniature      = 120,
        turntable      = 120,
        tram           = 110,
        disused        = 100,
        construction   = 100,
        platform       = 190,
    },
    aeroway = {
        runway         = 160,
        taxiway        = 150,
    },
    boundary = {
        administrative =  0,
    },

 -- bridge = {
 --     yes            = 103,
 --     movable        = 102,
 --     viaduct        = 103,
 -- },
}

setmetatableindex(stacking,function(t,k)
    local v = setmetatableindex(function(t,k)
        t[k] = false return false
    end)
    t[k] = v
    return v
end)

-- reservoir_covered: @ bachotex

local colors = {

    -- these concern details:

    amenity = {
        arts_centre               = true,
        bar                       = true,
        bicycle_parking           = true,
        college                   = true,
        courthouse                = true,
        fountain                  = true,
        hospital                  = true,
        kindergarten              = true,
        marketplace               = true,
        parking                   = true,
        parking_space             = true,
        pharmacy                  = true,
        place_of_worship          = true,
        police                    = true,
        restaurant                = true,
        school                    = true,
        shower                    = true,
        social_facility           = true,
        toilets                   = true,
        townhall                  = true,

     -- university                = true, -- no, it will mark all red .. maybe some other color so we need stacking

     -- atm                       = true,
        bank                      = true,
     -- bbq                       = true,
        bicycle_parking           = true,
        bicycle_repair_station    = true,
        cafe                      = true,
     -- car_sharing               = true,
        car_wash                  = true,
     -- charging_station          = true,
        childcare                 = true,
        clinic                    = true,
     -- clock                     = true,
        clubhouse                 = true,
        college                   = true,
        community_centre          = true,
     -- compressed_air            = true,
        computer_lab              = true,
     -- drinking_water            = true,
        events_venue              = true,
        fast_food                 = true,
        fire_station              = true,
        fountain                  = true,
        fuel                      = true,
     -- ice_cream                 = true,
        library                   = true,
        mailroom                  = true,
     -- microwave                 = true,
     -- parking_entrance          = true,
     -- parking_space             = true,
        pharmacy                  = true,
        place_of_worship          = true,
     -- post_box                  = true,
        post_office               = true,
        recycling                 = true,
        research_institute        = true,
     -- social_facility           = true,
        theatre                   = true,
     -- vending_machine           = true,
     -- waste_basket              = true,
     -- waste_disposal            = true,
        wellness_centre           = true,

    },

    -- these are basic:

    boundary = {
        aboriginal_lands = true,
        national_park    = true,
        protected_area   = true,
        administrative   = true,
    },
    building = {
        apartments       = true,
        bandstand        = true,
        cathedral        = true,
        civic            = true,
        commercial       = true,
        construction     = true, -- no roadtrip
        garage           = true,
        government       = true,
        hospital         = true,
        house            = true,
        houseboat        = true,
        hut              = true,
        industrial       = true,
        kiosk            = true,
        public           = true,
        residential      = true,
        retail           = true,
        roof             = true,
        school           = true,
        shed             = true,
        townhall         = true,
        yes              = true,

        university       = true,
        dormitory        = true,
        barn             = true,
        bridge           = true,
        detached         = true,
        farm_auxiliary   = true,
        grandstand       = true,
        greenhouse       = true,
        kindergarten     = true,
        parking          = true,
        stable           = true,
        stadium          = true,
        toilets          = true,

    },
    emergency = {
        designated       = true,
        destination      = true,
        no               = true,
        official         = true,
        yes              = true,
    },
    man_made = {
        breakwater       = true,
        bridge           = true,
        instrument       = true,
        pier             = true,
        quay             = true,
        tower            = true,
        windmill         = true,
        cutline          = true,
        embankment       = true,
        groyne           = true,
        pipeline         = true,
    },
    natural = {
        arete            = true,
        cliff            = true,
        earth_bank       = true,
        ridge            = true,
        sand             = true,
        scrub            = true,
        tree_row         = true,
        water            = true,
        wetland          = true,
        wood             = true,
        fault            = true,
    },
    barrier = {
        chain            = true,
        city_wall        = true,
        fence            = true,
        gate             = true,
        guard_rail       = true,
        hedge            = true,
        retaining_wall   = true,
        wall             = true,
        yes              = true,
    },
    leisure = {
        garden           = true,
        ice_rink         = true,
        marina           = true,
        park             = true,
        pitch            = true,
        playground       = true,
        slipway          = true,
        sports_centre    = true,
        track            = true,
        beach            = true,
    },
    boat = {
        yes              = true,
    },
    landuse = {
        allotments       = true,
        cemetery         = true,
        commercial       = true,
        construction     = true,
        forest           = true,
        grass            = true,
        industrial       = true,
        meadow           = true,
        residential      = true,
        static_building  = true,
        village_green    = true,
    },
    ["bridge:support"] = {
        pier             = true,
    },
    golf = { -- funny, this category
        cartpath         = true,
        hole             = true,
        path             = true,
    },
    area = {
        yes              = true,
    },
    bridge = {
        yes              = true,
        movable          = true,
        viaduct          = true,
    },
    agricultural = {
        yes              = true,
        no               = true,
    },
    historic = {
        citywalls        = true,
    },
    tourism = {
        yes              = true,
    },
    power = {
        cable            = true,
        line             = true,
        minor_line       = true,
    },
    junction = {
        yes              = true,
    },
    water = {
        river            = true,
        basin            = true,
    },

    -- these indicate routes:

    highway = {
        corridor         = true,
        bridleway        = true,
        cycleway         = true,
        footway          = true,
        living_street    = true,
        motorway         = true,
        motorway_link    = true,
        path             = true,
        pedestrian       = true,
        platform         = true,
        primary          = true,
        primary_link     = true,
        raceway          = true,
        residential      = true,
        rest_area        = true,
        road             = true,
     -- secondary        = true,
        secondary_link   = true,
        service          = true,
        services         = true,
        steps            = true,
        tertiary         = true,
        tertiary_link    = true,
        track            = true,
        trunk            = true,
        trunk_link       = true,
        unclassified     = true,
    },
    waterway = {
        canal            = true,
        derelict_canal   = true,
        ditch            = true,
        drain            = true,
        river            = true,
        stream           = true,
        tidal_channel    = true,
        wadi             = true,
        weir             = true,
    },
    railway = {
        construction     = true,
        disused          = true,
        funicular        = true,
        light_rail       = true,
        miniature        = true,
        monorail         = true,
        narrow_gauge     = true,
        platform         = true,
        preserved        = true,
        rail             = true,
        station          = true,
        subway           = true,
        tram             = true,
        turntable        = true,
    },

    aeroway = {
        runway           = true,
        taxiway          = true,
    },
    aerialway = {
        station          = true,
    },
}

-- We use this 'inside' knowledge encoded in the mentioned script to avoid bad fills
-- (for instance polygons can be unconnected and unordered). We define the table a bit
-- different.

local forcedlines = {
    golf      = { "cartpath", "hole", "path" },
    emergency = { "designated", "destination", "no", "official", "yes" },
    historic  = { "citywalls" },
    leisure   = { "track", "slipway" },
    man_made  = { "breakwater", "cutline", "embankment", "groyne", "pipeline" },
    natural   = { "cliff", "earth_bank", "tree_row", "ridge", "arete", "fault" },
    power     = { "cable", "line", "minor_line" },
    tourism   = { "yes"},
    waterway  = { "canal", "derelict_canal", "ditch", "drain", "river", "stream", "tidal_channel", "wadi", "weir" },
}

do

    local function never(t,k) t[k] = false return false end

    for k, v in next, forcedlines do
        forcedlines[k] = setmetatableindex(tohash(v),never)
    end

    setmetatableindex(forcedlines,function(t,k)
        local v = setmetatableindex(never)
        t[k] = v
        return v
    end)

end

-- For fast checking we apply the usual context tricks:


for k, v in next, colors do
    for kk, vv in next, v do
        v[kk] = "osm:" .. k .. ":" .. kk
    end
end

-- We draw and fill but sometimes we do both:

local lines = {
    amenity  = true,
    building = true,
    man_made = true,
    boat     = true,
}

-- When checking labels for a while I had a blacklist of tags (keys) but
-- dropped that when most was done. So, we're now ready for the real deal:

-- this only works for positive numbers

local f_f_degree_to_str = formatters["%d°%d’%.0f”"]

local function f_degree_to_str(num)
    local deg = floor(num)
    num = (num - deg) * 60
    local min = floor(num)
    num = (num - min) * 60
    local sec = num
    return f_f_degree_to_str(deg,min,sec)
end

-- local f_pattern     = formatters["/osm/(way|relation)[@visible='true']/tag[@k='%s']"]
local f_pattern     = formatters["/osm/(way|relation)[@visible!='false']/tag[@k='%s']"]
local f_way         = formatters["/osm/way[@id='%s']"]
local f_relation    = formatters["/osm/relation[@id='%s']"]

-- We could reuse paths and concat 0,n in the call but when testing it the gain was
-- not much so I went for readability.

local f_draw        = formatters['D %--t W "%s";']
local f_fill        = formatters['F %--t--C W "%s";']
local f_both        = formatters['P := %--t--C; F P W "%s"; D P W "white" L 2;']
local f_draw_s      = formatters['D %--t W "%s" L %s;']
local f_fill_s      = formatters['F %--t--C W "%s" L %s;']
local f_both_s      = formatters['P := %--t--C; F P W "%s"; D P W "white" L %s;']

local f_nodraw      = formatters['ND %--t;']
local f_nofill      = formatters['NF %--t--C;']
local f_nodraw_s    = formatters['ND %--t;']
local f_nofill_s    = formatters['NF %--t--C;']

local f_background  = formatters['F %--t -- C W "osm:background";']
local f_bounds      = formatters['setbounds currentpicture to %--t--C withstacking (0,250);']
local f_clipped     = formatters['clip currentpicture to %--t--C withstacking (0,250);']

-- For now no labels are printed, also because that's now what we use this for. At
-- some point I will provide some hooks to put text at coordinates.

-- local f_draw_p      = formatters["path p ; p := %--t ; D p W %s;"]
-- local f_fill_p      = formatters["path p ; p := %--t -- C ; F p W %s;"]
-- local f_textext     = formatters['draw (textext("\\bf %s") scaled 0.35) shifted center p withcolor white;']

-- Grids were also part of the original code, so I kept that. It's done a bit more
-- efficient by using a single path.

local f_draw_grid_b = formatters['nodraw %--t L 100;']
local f_draw_grid_e = formatters['dodraw origin dashed %s withcolor "osm:grid" withpen pencircle scaled %N  L 100;']
local f_label_lat   = formatters['label.urt((textext("\\infofont\\strut %s")), %s shifted (3,0)) withcolor white L 100;']
local f_label_lon   = formatters['label.top((textext("\\infofont\\strut %s")), %s shifted (0,3)) withcolor white L 100;']

local beginmp = [[
    begingroup ;
    pickup pencircle scaled 1 ;
    save P ; path P ;
    save D ; let D = draw ;
    save F ; let F = fill ;
    save C ; let C = cycle ;
    save W ; let W = withcolor ;
    save L ; let L = withstacking ;
    save ND ; let ND = nodraw ;
    save DD ; let DD = dodraw ;
    save NF ; let NF = nofill ;
    save DF ; let DF = dofill ;
]]

local endmp = [[
    endgroup;
]]

local p_strip = lpeg.Cs( (
--  (P([[<tag k="TMC:]]) * (1 - P("/>"))^1 * P("/>") * S("\n\r\t\f ")^0) / ""
-- +
    (
          ( P("version") + P("changeset") + P("timestamp") + P("user") + P("uid") )
          * P('="') * (1-P('"'))^0 * P('"')
    ) / ""
  + P(">") * (S("\n\r\t\f ")^1 / "") * P("<")
  + P('visible="true"') / ""
  + P(1)
)^1 )

function openstreetmap.convert(specification)

    local starttime = os.clock()
    local filename  = specification.filename

    if not io.exists(filename) then
        return
    end

    report("processing file %a",filename)

    -- we can consider stripping crap first

 -- local root   = xml.load(filename)

    local root = io.loaddata(filename)
    local olds = #root
          root = lpegmatch(p_strip,root)
    local news = #root

    report("original size %i bytes, stripped down to %i bytes",olds,news)

    root = xml.convert(root)

    if root.error then
        report("error in xml",olds,news)
        return
    else
        report("xml data loaded")
    end
    local bounds = xmlfirst(root,"/osm/bounds")
    if not bounds then
        return
    end

    local usercolors = specification.used
    local usedcolors = table.copy(colors)

    if usercolors then
        for k, v in next, usercolors do
            local u = usedcolors[k]
            if not u then
                -- error
            elseif v == false then
                usedcolors[k] = false
             -- for k in next, u do
             --     u[k] = false
             -- end
            elseif type(v) == "string" then
                for k in next, u do
                    u[k] = v
                end
            elseif type(v) == "table" then
                for kk, vv in next, v do
                    if vv == false then
                        u[kk] = false
                    elseif type(vv) == "string" then
                        u[kk] = vv
                    end
                end
            end
        end
    end

 -- inspect(usedcolors)

    local minlat     = bounds.at.minlat
    local minlon     = bounds.at.minlon
    local maxlat     = bounds.at.maxlat
    local maxlon     = bounds.at.maxlon
    local midlat     = 0.5 * (minlat + maxlat)
    local deg_to_rad = math.pi / 180.0
    local scale      = 3600 -- vertical scale: 1" = 1cm

 -- local function f_pair(lon, lat)
 --     return formatters("(%.3Ncm,%.3Ncm)", (lon - minlon) * scale * cos(midlat * deg_to_rad), (lat-minlat) * scale)
 -- end

    local f_f_pair = formatters["(%.3Ncm,%.3Ncm)"]

    local function f_pair(lon, lat)
        return f_f_pair((lon - minlon) * scale * cos(midlat * deg_to_rad), (lat-minlat) * scale)
    end

    local rendering   = table.tohash(order)
    local coordinates = { }
    local ways        = { }
    local result      = { }
    local r           = 0
    local done        = { }
    local missing     = false -- setmetatableindex("table")
    local layers      = { }
    local areas       = { }

    for c in xmlcollected(root,"/osm/node") do
        local a = c.at
        coordinates[a.id] = a
    end

    for c in xmlcollected(root,"/osm/way") do
        ways[c.at.id] = c
    end

    for c in xml.collected(root,"tag[@k='area']") do
        areas[c] = c.at.v
    end

    for c in xml.collected(root,"tag[@k='layer']") do
        layers[c] = c.at.v
    end

    -- Collecting is more a private option. It doesn't save much on the output
    -- but looks better with transparency, which makes no sense using anyway.

    local collected = specification.collect and setmetatableindex(function(t,k)
        local v = setmetatableindex(function(t,k)
            local v = {
                draw = setmetatableindex("table"),
                fill = setmetatableindex("table"),
            }
            t[k] = v
            return v
        end)
        t[k] = v
        return v
    end) or false

    local function drawshapes(what,order)

        -- see bachotex rendering for an example
        -- also layer and polygon

        function xml.expressions.osm(k)
            return usedcolors[k]
        end

        local function getcolor(r)
            local t = xmlfirst(r,"/tag[osm(@k)]")
            if t then
                local at  = t.at
                local v   = at.v
                if v ~= "no" then
                    local k   = at.k
                    local col = usedcolors[k][v]
                    -- we need an example: if layers[r] then print(layers[r]) end
                    if col then
                        -- todo : trace colors and stacking
                        return k, col, lines[k], stacking[k][v], forcedlines[k][v]
                    elseif missing then
                        missing[k][v] = (missing[k][v] or 0) + 1
                    end
                end
            end
        end

        local function addpath(r, p, n)
         -- if done[r] then
         --     print("AGAIN")
         -- else
                for c in xmlcollected(r,"/nd") do
                    local coordinate = coordinates[c.at.ref]
                    if coordinate then
                        n = n + 1  p[n] = f_pair(coordinate.lon, coordinate.lat)
                    end
                end
         --     done[r] = true
         -- end
            return p, n
        end

        local checkpath = collected and

            function(parent,p,n)
                local what, color, both, stacking, forced = getcolor(parent)
                if what and rendering[what] then
                    local where = collected[stacking or order]
                    if not polygons[what] or forced or areas[parent] == "no" then
                        insert(where[color]  .draw, f_nodraw(p))
                    elseif both then
                        insert(where[color]  .fill, f_nofill(p))
                        insert(where["white"].draw, f_nodraw(p))
                    else
                        insert(where[color]  .fill, f_nofill(p))
                    end
                end
            end

        or

            function(parent,p,n)
                local what, color, both, stacking, forced = getcolor(parent)
                if what and rendering[what] then
                    r = r + 1
                 -- if not stacking then
                 --     stacking = order
                 -- end
                    if not polygons[what] or forced or areas[parent] == "no" then
                        result[r] = stacking and f_draw_s(p,color,stacking) or f_draw(p,color)
                    elseif both then
                        result[r] = stacking and f_both_s(p,color,stacking) or f_both(p,color)
                    else
                        result[r] = stacking and f_fill_s(p,color,stacking) or f_fill(p,color)
                    end
                end
            end

        -- There are ways and relations. Relations can have members that point to
        -- ways but also relations. My impression is that we can stick to way members
        -- but I'll deal with that when needed.

        for c in xmlcollected(root,f_pattern(what)) do
            local parent = xmlparent(c)
            local tag    = parent.tg
            if tag == "way" then
                local p, n = addpath(parent, { }, 0)
                if n > 1 then
                    checkpath(parent,p,n)
                end
            elseif tag == "relation" then
                if xmlfilter(parent,"xml://tag[@k='type' and (@v='multipolygon' or @v='boundary' or @v='route')]") then
                    local what, color, both, stacking, forced = getcolor(parent)
                    if rendering[what] then
                        local p, n = { }, 0
                        for m in xmlcollected(parent,"/member[(@type='way') and (@role='outer')]") do
                         -- local f = xmlfirst(root,f_way(m.at.ref))
                            local f = ways[m.at.ref]
                            if f then
                                p, n = addpath(f,p,n)
                            end
                        end
                        if n > 1 then
                            checkpath(parent,p,n)
                        end
                    end
                else
                    for m in xmlcollected(parent,"/member[@type='way']") do
                     -- local f = xmlfirst(root,f_way(m.at.ref))
                        local f = ways[m.at.ref]
                        if f then
                            local p, n = addpath(f, { }, 0)
                            if n > 1 then
                                checkpath(parent,p,n)
                            end
                        end
                    end
                end
            end
        end

    end

    -- As with the other latitude and longitude mapping calculations the next magick
    -- comes from Mojca.

    local function drawgrid()
        local lat0 = ceil (3600*minlat)
        local lat1 = floor(3600*maxlat)
        local pen  = tonumber(specification.griddot) or 1.5
        local lat
        local labels = { }
        for i=lat0,lat1 do
            lat = i/3600
            local p = {
                f_pair(minlon,lat),
                f_pair(maxlon,lat),
            }
            r = r + 1 result[r] = f_draw_grid_b(p)
            if i ~= lat0 and i ~= lat1 then
                labels[#labels+1] = f_label_lat(f_degree_to_str(lat),p[1])
            end
        end

        local lon0 = ceil (1800*minlon)*2
        local lon1 = floor(1800*maxlon)*2
        local lon
        for i=lon0,lon1,2 do
            lon=i/3600
            local p = {
                f_pair(lon, minlat),
                f_pair(lon, maxlat),
            }
            r = r + 1 result[r] = f_draw_grid_b(p)
            if i ~= lon0 and i ~= lon1 then
                labels[#labels+1] = f_label_lon(f_degree_to_str(lon),p[1])
            end
        end
        r = r + 1 result[r] = f_draw_grid_e("withdots", pen)
        r = r + 1 result[r] = concat(labels)
    end

    -- We add a background first and clip later. Beware: There can be substantial bits
    -- outside the clip path (like rivers) but because paths are not that detailed we
    -- don't waste time on building a cycle. We could check if points are outside the
    -- boundingbox and then use the metapost buildpath macro .. some day.

    local boundary = {
        f_pair(minlon,minlat),
        f_pair(maxlon,minlat),
        f_pair(maxlon,maxlat),
        f_pair(minlon,maxlat),
    }

    r = r + 1 result[r] = beginmp
    r = r + 1 result[r] = f_background(boundary)

 -- r = r + 1 result[r] = "drawoptions (withtransparency (1,.5)) ;"

    -- use stacking instead

    for i=1,#order do
        local o = order[i]
        if usedcolors[o] then
            drawshapes(o,i)
        end
    end

    if specification.grid == "dots" then
        drawgrid()
    end

    if collected then

        local f_flush = formatters[') W "%s" L %s;']

        for stacking, colors in sortedhash(collected) do
            for color, bunch in next, colors do
                local draw = bunch.draw
                local fill = bunch.fill
                if fill and #fill > 0 then
                    r = r + 1 result[r] = "draw image ("
                    r = r + 1 result[r] = concat(fill)
                    r = r + 1 result[r] = 'DF origin--cycle;'
                    r = r + 1 result[r] = f_flush(color,stacking) ;
                end
                if draw and #draw > 0 then
                    r = r + 1 result[r] = "draw image ("
                    r = r + 1 result[r] = concat(draw)
                    r = r + 1 result[r] = 'DD origin;'
                    r = r + 1 result[r] = f_flush(color,stacking+1) ;
                end
            end
        end

    end

--     r = r + 1 result[r] = f_bounds(boundary)
    r = r + 1 result[r] = f_clipped(boundary)
    r = r + 1 result[r] = endmp

    if missing then
        inspect(missing)
    end

    result = concat(result)

    report("%s characters metapost code, preprocessing time %0.3f seconds",#result,os.clock()-starttime)

    return result

end

function mp.lmt_do_openstreetmap()
    local specification = metapost.getparameterset("openstreetmap")
    return openstreetmap.convert(specification)
end