组队距离折损：离队过远的经验衰减

local function grant(member, exp)
    setplayvar(member, "EXP_ADD", exp)   -- 不看距离，挂机白拿
end

local function grant(member, lx, ly, exp)
    local dx = getplayvar(member, "X") - lx
    local dy = getplayvar(member, "Y") - ly
    local dist = math.sqrt(dx * dx + dy * dy)
    local rate = dist <= 20 and 1 or (dist <= 50 and 0.5 or 0)
    if rate > 0 then
        setplayvar(member, "EXP_ADD", math.floor(exp * rate))
    end
end