cartographer/map_api.lua

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

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

    _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.fill_local(id, x, z)
    local map = cartographer.get_map(id);

    if map ~= nil 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
    minetest.chat_send_all("[" .. tostring(x) .. ", " .. tostring(z) .. "] - [" .. tostring(map.x - 2) .. ", " .. tostring(map.z - 2) .. "], [" .. tostring(map.x + map.w + 1) .. ", " .. tostring(map.z + map.h + 1) .. "]");
        cartographer.fill(map, x - 2, z - 2, 5, 5);
    end
end

local timer = 0;

minetest.register_globalstep(function(dt)
    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();
            local player_x = tochunk(pos.x);
            local player_y = tochunk(pos.z);
            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"), player_x, player_y);
                end
            end
            for i = -2,2 do
                for j = -2,2 do
                    local adjusted_pos = {
                        x = tochunk(pos.x + fromchunk(i)),
                        y = tochunk(pos.y),
                        z = tochunk(pos.z + fromchunk(j)),
                    }
                    cartographer.queue_region(adjusted_pos);
                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

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 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 (biome.min_height == nil or height >= biome.min_height) and (biome.max_height == nil or height <= biome.max_height) then
            return biome.textures[math.min(detail, #biome.textures)];
        end
    end

    return nil;
end