箭雨覆盖：头顶落下的死亡地带

fx-arrowrain

local arrowRain = { WARN = 1.0, DURATION = 2.6, TICK = 0.5 }

function arrowRain:Cast(x, y, rx, ry)
    self._zone = { x = x, y = y, rx = rx, ry = ry }
    self._t = self.WARN + self.DURATION
    self._tickAcc = 0
    self._warnRing = CreateWarnEllipse(x, y, rx, ry)      -- 预警层
    self._warnRing:AccelerateBlink(self.WARN)             -- 明灭加速
end

function arrowRain:Update(dt)
    if not self._zone then return end
    self._t = self._t - dt

    if self._t <= 0 then self:Finish(); return end

    if self._t <= self.DURATION then                      -- 落下层
        if math.random() < dt * 16 then
            local a, rr = math.random() * math.pi * 2, math.sqrt(math.random())
            local tx = self._zone.x + math.cos(a) * rr * self._zone.rx
            local ty = self._zone.y + math.sin(a) * rr * self._zone.ry
            SpawnFallingArrow(tx + 40, -20, tx, ty, 700)  -- 45°斜落+插地
        end
        self._tickAcc = self._tickAcc + dt
        if self._tickAcc >= self.TICK then                -- 结算层
            self._tickAcc = self._tickAcc - self.TICK
            for _, m in ipairs(GetMonstersInEllipse(self._zone)) do
                m:OnHit(9)
            end
        end
    end
end