client.lua

function OnWorldPostUpdate()
    if connection == nil then
        return
    end

    if os.getenv("ROLE") == "R" then
        do_receive()
        return
    end

    local grid_world = world_ffi.get_grid_world()
    local chunk_map = grid_world.vtable.get_chunk_map(grid_world)
    local thread_impl = grid_world.mThreadImpl

    local begin = thread_impl.updated_grid_worlds.begin
    local end_ = begin + thread_impl.chunk_update_count

    local count = thread_impl.chunk_update_count

    local result = ''

    for i = 0, count - 1 do
        local it = begin[i]

        local start_x = it.update_region.top_left.x
        local start_y = it.update_region.top_left.y
        local end_x = it.update_region.bottom_right.x
        local end_y = it.update_region.bottom_right.y

        start_x = start_x - 1
        start_y = start_y - 1
        end_x = end_x + 1
        end_y = end_y + 2

        if start_x < end_x and start_y < end_y then
            local area = world.encode_area(chunk_map, start_x, start_y, end_x, end_y, encoded_area)
            if area == nil then
                return
            end

            local str = ffi.string(area, world.encoded_size(area))
            result = result .. str
        end
    end

    for i = 0, tonumber(thread_impl.world_update_params_count) - 1 do
        local wup = thread_impl.world_update_params.begin[i]
        local start_x = wup.update_region.top_left.x
        local start_y = wup.update_region.top_left.y
        local end_x = wup.update_region.bottom_right.x
        local end_y = wup.update_region.bottom_right.y
        local area = world.encode_area(chunk_map, start_x, start_y, end_x, end_y, encoded_area)
        if area == nil then
            return
        end

        local str = ffi.string(area, world.encoded_size(area))
        result = result .. str
    end
    send_str(result)
end