足迹流光：行走轨迹的特效拖尾

-- 错误：每步广播特效，带宽与帧率双炸
function onStep(p, x, y)
    broadcastFx(p, x, y)
end

local GAP2 = 4
local function onWalk(p, x, y)
    local dx = x - (getplayvar(p, "lastX") or 0)
    local dy = y - (getplayvar(p, "lastY") or 0)
    if dx * dx + dy * dy < GAP2 then return end
    setplayvar(p, "lastX", x)
    setplayvar(p, "lastY", y)
    if getplayvar(p, "hasTrail")
        and not inCombat(p) then
        spawnTrailFx(p, x, y)
    end
end