Example Tilemaker process file.

process-demo.lua

-- Based on process-example.lua

-- Assign nodes to a layer, and set attributes, based on OSM tags
function node_function(node)
	-- POIs go to a "poi" layer (we just look for amenity and shop here)
	local amenity = Find("amenity")
	local shop = Find("shop")
	if amenity~="" or shop~="" then
		Layer("poi")
		if amenity~="" then Attribute("class",amenity)
		else Attribute("class",shop) end
		Attribute("name", Find("name"))
		AttributeNumeric("rank", 3)
	end
	
	-- Places go to a "place" layer
	local place = Find("place")
	if place~="" then
		Layer("place")
		Attribute("class", place)
		Attribute("name", Find("name"))
		if place=="city" then
			AttributeNumeric("rank", 4)
			MinZoom(3)
		elseif place=="town" then
			AttributeNumeric("rank", 6)
			MinZoom(6)
		else
			AttributeNumeric("rank", 9)
			MinZoom(10)
		end
	end

	-- Include peaks
	local natural = Find("natural")
	if natural == "peak" or natural == "volcano" then
		Layer("place", false)
		Attribute("class", natural)
		local ele = Find("ele")
		if ele ~= "" then
			local meter = math.floor(tonumber(ele) or 0)
			local feet = math.floor(meter * 3.2808399)
			AttributeNumeric("ele", meter)
			AttributeNumeric("ele_ft", feet)
		end
		Attribute("name", Find("name"))
	end
end

-- Assign ways to a layer, and set attributes, based on OSM tags
function way_function()
	local highway  = Find("highway")
	local waterway = Find("waterway")
	local building = Find("building")

    -- Trails
    if highway=="path" then
        Layer("trail", false)
        MinZoom(6)

        -- Retain common trail osm tags
        Attribute("bicycle", Find("bicycle"))
        Attribute("foot", Find("foot"))
        Attribute("horse", Find("horse"))
        Attribute("surface", Find("surface"))
        Attribute("sac_scale", Find("sac_scale"))
        Attribute("mtb:scale:imba", Find("mtb:scale:imba"))
		Attribute("osm_id", Id())
		Attribute("name", Find("name"))

	elseif highway=="footway" and Find("footway")=="sidewalk" then
		-- silently ignore sidewalks
		return

	elseif highway=="footway" and Find("footway")=="crossing" then
		-- silently ignore street crossings
		return

	-- Roads
	elseif highway~="" then
		Layer("transportation", false)
		if highway=="unclassified" or highway=="residential" then highway="minor" end
		Attribute("class", highway)
		Attribute("name", Find("name"))

	elseif waterway=="canal" and Find("nhd:ftype")=="CanalDitch" then
		-- silently ignore ditches
		return

	elseif waterway=="stream" or waterway=="river" or waterway=="canal" then
		-- Rivers
        -- discard intermittent waterways (to reduce file size)
        if Find("intermittent")~="yes" then
		    Layer("waterway", false)
		    Attribute("class", waterway)
		    AttributeNumeric("intermittent", 0)
			Attribute("name", Find("name"))
        end

	-- Lakes and other water polygons
	elseif Find("natural")=="water" then
		Layer("water", true)
		if Find("water")=="river" then
			Attribute("class", "river")
		else
			Attribute("class", "lake")
		end
		Attribute("name", Find("name"))
	end

	-- We could also add things like grass, scrub, wood
	-- https://www.openstreetmap.org/way/421699900#map=17/38.524876/-106.028020
	-- https://www.openstreetmap.org/way/501069060#map=14/38.54088/-105.98538
	-- https://www.openstreetmap.org/way/501071079
end

-- National Forests and Parks (these are relations)
-- San isabel : https://www.openstreetmap.org/relation/396343#map=8/38.309/-105.744
-- Sand dunes wildeness : https://www.openstreetmap.org/relation/16848699#map=12/37.7661/-105.5755
-- Browns canyon : https://www.openstreetmap.org/relation/5916900#map=13/38.70125/-106.04213

function relation_scan_function()
	local boundary = Find("boundary")
	local leisure  = Find("leisure")
	if boundary=="national_park" or boundary=="protected_area" or leisure=="nature_reserve" then
		Accept()
	end
end

function relation_function()
	local boundary = Find("boundary")
	local leisure  = Find("leisure")
	if boundary=="national_park" or boundary=="protected_area" then
		Layer("park",true)
		Attribute("class",boundary)
		Attribute("name", Find("name"))
	elseif leisure=="nature_reserve" then
		Layer("park",true)
		Attribute("class",leisure )
		Attribute("name", Find("name"))
	end
end