【网络通信】九宫格视野：同屏广播的范围控制

-- 以 400 为一格边长，登记玩家所在桶
local GRID = 400
local buckets = {}
local function cellKey(map, x, y)
    return map .. "_" .. math.floor(x / GRID) .. "_" .. math.floor(y / GRID)
end
local function enterCell(player, map, x, y)
    local oldKey = getplayvar(player, "HUMAN", "CellKey")
    if oldKey and buckets[oldKey] then
        buckets[oldKey][player] = nil
    end
    local key = cellKey(map, x, y)
    buckets[key] = buckets[key] or {}
    buckets[key][player] = true
    setplayvar(player, "HUMAN", "CellKey", key, false)
end

-- 向九格内玩家广播文本消息
local function broadcast9(map, x, y, text)
    local cx, cy = math.floor(x / GRID), math.floor(y / GRID)
    for dx = -1, 1 do
        for dy = -1, 1 do
            local key = map .. "_" .. (cx + dx) .. "_" .. (cy + dy)
            local cell = buckets[key]
            if cell then
                for actorName in pairs(cell) do
                    local target = class(actorName)
                    sendmsg(target, 1, 0, text)
                end
            end
        end
    end
end