龙卷风：把怪全卷进风眼里

fx-tornado

local Tornado = {}
local CONST = { MSG_ID = 12330, KEY = "Tornado", PULL = 100, TANGENT = 90, DURATION = 5 }

function Tornado.Cast(casterID, eyeX, eyeY)
    Tornado._eye = { x = eyeX, y = eyeY }
    Tornado._left = CONST.DURATION
    Tornado._sched = SL:Schedule(function(dt)
        Tornado:Update(dt)
    end, 0.02)
end

function Tornado:Update(dt)
    self._left = self._left - dt
    if self._left <= 0 then
        SL:UnSchedule(self._sched)
        self._sched = nil
        return
    end
    for _, id in ipairs(SL:GetValue("FIND_IN_VIEW_MONSTER_LIST") or {}) do
        local mx = SL:GetValue("ACTOR_POSITION_X", id)
        local my = SL:GetValue("ACTOR_POSITION_Y", id)
        local dx, dy = self._eye.x - mx, self._eye.y - my
        local dist = math.sqrt(dx * dx + dy * dy)
        if dist > 40 then                                -- 风眼内不再吸
            local pull = CONST.PULL * math.min(1, dist / 230)
            -- 向心 + 切向: 两个正交分量合成螺旋
            SL:SetActorVelocity(id,
                dx / dist * pull - dy / dist * CONST.TANGENT,
                dy / dist * pull + dx / dist * CONST.TANGENT)
        end
    end
end

return Tornado