帮会工事：捐料升级的城防减伤

; fortify.txt 工事配置
[一级] 木材=200 石材=100 减伤=8%
[二级] 木材=500 石材=300 减伤=16%
[三级] 木材=1000 石材=800 减伤=24%

local function donateMat(actor, guild, wood, stone)
    setsysvarex("fortW_" .. guild,
        (getsysvar("fortW_" .. guild) or 0) + wood)
    setsysvarex("fortS_" .. guild,
        (getsysvar("fortS_" .. guild) or 0) + stone)
    local lv = getsysvar("fortLv_" .. guild) or 0
    if lv < 3 then
        local wNeed = ({200, 500, 1000})[lv + 1]
        local sNeed = ({100, 300, 800})[lv + 1]
        if getsysvar("fortW_" .. guild) >= wNeed
            and getsysvar("fortS_" .. guild) >= sNeed then
            setsysvarex("fortLv_" .. guild, lv + 1)
            sendcentermsg(0, guild .. " 城防升至 "
                .. (lv + 1) .. " 级")
        end
    end
end