【框架设计】数学工具库：随机分布与夹取的公共函数

-- 数学工具库：加权随机
local M = {}
function M.weightedPick(entries, defaultKey)
    local total = 0
    for _, e in ipairs(entries) do
        total = total + math.max(0, e.weight)
    end
    if total <= 0 then
        return defaultKey
    end
    local roll = math.random() * total
    local acc = 0
    for _, e in ipairs(entries) do
        acc = acc + math.max(0, e.weight)
        if roll <= acc then
            return e.key
        end
    end
    return defaultKey
end
M.weightedPick = M.weightedPick

-- 数学工具库：夹取与插值
local player = class(actor)
function M.clamp(v, lo, hi)
    if v < lo then return lo end
    if v > hi then return hi end
    return v
end
function M.lerp(a, b, t)
    t = M.clamp(t, 0, 1)
    return a + (b - a) * t
end
local function shakeCoord(x, y, radius)
    return M.clamp(x + math.random(-radius, radius), 1, 999),
        M.clamp(y + math.random(-radius, radius), 1, 999)
end