【性能调优】视野剔除：屏外单位的心跳降频

-- 视野剔除：屏内屏外分组
local player = class(actor)
local VIEW_W, VIEW_H = 24, 18
local function inViewport(px, py, ux, uy)
    return math.abs(ux - px) <= VIEW_W / 2 and math.abs(uy - py) <= VIEW_H / 2
end
local function groupHeartbeat(player, units, px, py)
    local inside, outside = {}, {}
    for _, u in ipairs(units) do
        if inViewport(px, py, u.x, u.y) then
            inside[#inside + 1] = u
        else
            outside[#outside + 1] = u
        end
    end
    return inside, outside
end

-- 心跳下发：双频与回屏补发
local player = class(actor)
local BASE_SEC, LOW_SEC = 300, 1200
local function dispatchHeartbeat(unit, isInside)
    local sec = isInside and BASE_SEC or LOW_SEC
    if not isInside and unit.wasInside then
        sec = BASE_SEC
        unit.wasInside = false
        sendluamsg(unit.actor, 9999, 1, 0, 0, unit.pos)
    elseif isInside and not unit.wasInside then
        unit.wasInside = true
        sendluamsg(unit.actor, 9999, 0, 0, 0, unit.pos)
    end
    return sec
end