cartographer/map_api.lua

function cartographer.create_map(x, z, w, h, filled, detail, scale)
    local id = _cartographer.next_map_id;

    local map = {
        id = id,
        x = x,
        z = z,
        w = w,
        h = h,
        detail = detail,
        scale = scale,
        fill = {},
        markers = {},
    };

    _cartographer.maps[id] = map;
    if filled then
        cartographer.fill(map, x, z, w, h);
    end

    _cartographer.next_map_id = _cartographer.next_map_id + 1;

    return id;
end

function cartographer.get_map(id)
    return _cartographer.maps[id];
end

function cartographer.resize_map(id, w, h)
    local map = cartographer.get_map(id);
    if map ~= nil and w >= map.w and h >= map.h then
        map.w = w;
        map.h = h;
    end
end

function cartographer.fill(map, x, z, w, h)
    if map == nil then
        return;
    end

    for i = math.max(x, map.x),math.min(x + w - 1, map.x + map.w),1 do
        for j = math.max(z, map.z),math.min(z + h - 1, map.z + map.h),1 do
            map.fill[(i - map.x) + ((j - map.z) * map.w)] = map.detail;
        end
    end
end

function cartographer.set_marker(map, x, z, marker)
    if map == nil or x < map.x or x > map.x + map.w or z < map.z or z > map.z + map.h then
        return;
    end

    if not map.markers[x] then
        map.markers[x] = {
            [z] = marker,
        };
    else
        map.markers[x][z] = marker;
    end
end

function cartographer.get_marker(map, x, z)
    if map == nil or x < map.x or x > map.x + map.w or z < map.z or z > map.z + map.h or not map.markers[x] then
        return nil;
    end

    return map.markers[x][z];
end

-- Fill in the local area of a map around a position
-- id: A map ID
-- x: The x position, in world coordinates
-- z: The z position, in world coordinates
function cartographer.fill_local(id, x, z)
    local map = cartographer.get_map(id);

    x, z = cartographer.to_map_coordinates(map, x, z);

    -- TODO: Adjust size to match map scale
    if map and x >= map.x - 2 and x <= map.x + map.w + 1 and z >= map.z - 2 and z <= map.z + map.h + 1 then
        cartographer.fill(map, x - 2, z - 2, 5, 5);
    end
end

-- Convert a position in world coordinates to the given map's coordinate system
-- map: The map to use as reference, or nil to use the default size (map scale of 1)
-- x: The x position, in world coordinates
-- z: The z position, in world coordinates
--
-- Returns The converted x and z coordinates
function cartographer.to_map_coordinates(map, x, z)
    if not map or map.scale == 0 then
        return tochunk(x), tochunk(z);
    end

    return math.floor(tochunk(x) / map.scale + 0.5), math.floor(tochunk(z) / map.scale + 0.5);
end

local timer = 0;
minetest.register_globalstep(function(dt)
    -- TODO: We need a better way to do this. minetest.after maybe?
    timer = timer - dt;
    if timer < 0 then
        timer = timer + 5;

        -- Fill in all player-held maps
        for _,p in ipairs(minetest.get_connected_players()) do
            local inventory = p:get_inventory();
            local pos = p:get_pos();
            if pos.y > -10 then
                for i = 1,inventory:get_size("main") do
                    local stack = inventory:get_stack("main", i);

                    if stack:get_name() == "cartographer:map" then
                        cartographer.fill_local(stack:get_meta():get_int("cartographer:map_id"), pos.x, pos.y);
                    end
                end
                for i = -2,2 do
                    for j = -2,2 do
                        local adjusted_pos = {
                            x = pos.x + fromchunk(i),
                            y = pos.y,
                            z = pos.z + fromchunk(j),
                        }
                        cartographer.queue_region(adjusted_pos);
                    end
                end
            end
        end

        for i = 1,10 do
            cartographer.scan_regions();
        end
    end
end)

-- Register a biome with textures to display
-- name: A string containing the biome name
-- textures: A table of texture names.
--           These should correspond with detail levels,
--           any detail level past the length of the table will return the last texture
-- (Optional) min_height: The minimum Y position where this biome data should be used
-- (Optional) max_height: The maximum Y position where this biome data should be used
function cartographer.register_biome(name, textures, min_height, max_height)
    _cartographer.biome_lookup[#_cartographer.biome_lookup + 1] = {
        name = name,
        textures = textures,
        min_height = min_height,
        max_height = max_height,
    };
end

-- Format marker ids to allow their use as formspec element ids.
-- We're mostly concerned with guarding against the : character because it is
-- common for ids and has an alternate meaning in formspecs.
-- id: The id to format
--
-- Returns the formatted id
local function format_marker_id(id)
    return id:gsub(":", "_");
end

-- Find the marker data for a given id
-- id: The id to search for
--
-- Returns the marker data, or nil if not found
function cartographer.get_marker_data(id)
    if not id then
        return nil;
    end

    id = format_marker_id(id);
    for _,marker in pairs(_cartographer.marker_lookup) do
        if marker.id == id then
            return marker;
        end
    end

    return nil;
end

-- Register a marker with textures to display
-- id: A string containing the id of the marker
-- name: A string containing the displayedname of the marker
-- textures: A table of texture names.
--           These should correspond with detail levels,
--           any detail level past the length of the table will return the last texture
function cartographer.register_marker(id, name, textures)
    if not id then
        return nil;
    end

    id = format_marker_id(id);
    local existing_marker = cartographer.get_marker_data(id);
    if existing_marker then
        existing_marker.name = name;
        existing_marker.textures = textures;
    else
        _cartographer.marker_lookup[#_cartographer.marker_lookup+1] = {
            id = id,
            name = name,
            textures = textures,
        };
    end
end

function cartographer.is_filled(map, x, z)
    if map == nil then
        return false;
    end

    -- minetest.chat_send_all(tostring(x).. ", " .. tostring(z) .. "(" .. tostring(x + (z * map.w)) .."): " .. tostring(map.fill[x + (z * map.w)]));
    return map.fill[(x - map.x) + ((z - map.z) * map.w)] ~= nil;
end

-- Get an entry from a list for a given detail level
-- textures: An array of textures
-- detail: The detail level
--
-- Returns the entry at detail, or the last entry if detail is out-of-bounds
function cartographer.detail_texture(textures, detail)
    return textures[math.min(detail, #textures)];
end

-- Get the texture name (minus index/extension) for the given biome, height, and detail level.
-- name: A string containing the biome name
-- height: A number representing the Y position of the biome
-- detail: The detail level
-- Returns a string with a texture name, or nil if no matching biome entry was found.
function cartographer.get_biome_texture(name, height, detail)
    for _,biome in ipairs(_cartographer.biome_lookup) do
        if biome.name == name and (not biome.min_height or height >= biome.min_height) and (not biome.max_height or height <= biome.max_height) then
            return cartographer.detail_texture(biome.textures, detail);
        end
    end

    return nil;
end

-- Get the texture name (minus extension) for the given marker and detail level.
-- id: A string containing the marker id
-- detail: The detail level
-- Returns a string with a texture name, or nil if no matching marker was found.
function cartographer.get_marker_texture(id, detail)
    if not id then
        return nil;
    end

    id = format_marker_id(id);
    local marker = cartographer.get_marker_data(id);

    if marker then
        return marker.textures[math.min(detail, #marker.textures)];
    end

    return nil;
end