Web 导出可行性

Web export feasibility

**这一步决定什么****What this stage decides**：「能导出到网页」和「导出后能正常用」是两件事 —— 差别通常在存档与性能。: \"Can export to the web\" and \"works after export\" are different claims — the gap usually shows up in saves and performance.

**本站的判断****Our judgement**：如果你需要长期存档、多人、或重度 3D，原生引擎；否则 Web 引擎迭代更快。: If you need long-term saves, multiplayer, or heavy 3D, use a native engine; otherwise a web engine iterates faster.

性质：本站的判断，未经实测Nature: the site's judgement, not measured

一句话：所有主流引擎都说能导出到网页。但「能导出」和「能正常用」差得很远。

In one line: every mainstream engine claims web export. But "can export" and "works properly" are far apart.

三个真正会出问题的地方

环节	常见问题
存档	⚠ 原生引擎的本地存档 API 在 Web 上通常不可用；要改用浏览器存储，这需要你自己改代码
性能	⚠ Web 构建默认不带优化；着色器编译、资源加载策略都要自己调
加载	首屏加载量可能几十 MB —— ⚠ 手机网络下会很慢

⚠ 这三项都需要改代码，不是导出时打个勾就完事。

The three things that actually break

Area	The common problem
Saves	⚠ A native engine's local-save API is usually unavailable on the web; you must switch to browser storage, which means changing code yourself
Performance	⚠ Web builds ship without optimisation by default; shader compilation and asset loading both need tuning
Loading	First load can be tens of megabytes — ⚠ very slow on mobile networks

⚠ All three require code changes. They are not a checkbox in the export dialog.

⚠ 一个结构性差异

原生引擎导出到 Web，本质上是把 C++/Rust 编译成 WebAssembly。

这带来两个后果：

1. 体积大 —— Rust/C++ 编出的 wasm 通常比原生 JS 大一个量级

2. ⚠ 性能损耗 —— WebAssembly 在浏览器里跑，但仍受 JS 主线程调度限制

⚠ 所以「用 Bevy 导出 Web」技术上可行，但通常不是你该选它的理由。

⚠ A structural difference

Exporting a native engine to the web is, underneath, compiling C++ or Rust to WebAssembly.

Two consequences:

1. It is large — wasm produced from Rust or C++ is typically an order of magnitude larger than native JS

2. ⚠ It costs performance — WebAssembly runs in the browser but is still subject to JS main-thread scheduling

⚠ So "export Bevy to the web" is technically possible, but it is usually not the reason to choose Bevy.

判断标准

你的需求	建议
短体验、无存档	✅ Web 引擎最省事
需要长期存档	⚠ 原生引擎 + 自己接浏览器存储
重度 3D	⚠ Web 引擎（Bevy/Unity 的 Web 导出损耗大）
⚠ 要发到 Steam	别考虑 Web —— Steam 有原生分发，没必要降级

How to decide

Your requirement	Advice
Short sessions, no saves	✅ A web engine is least work
Long-term saves	⚠ Native engine + your own browser-storage layer
Heavy 3D	⚠ Web engines (Bevy/Unity lose a lot in their web exports)
⚠ Shipping on Steam	Do not consider web — Steam ships natively, so there is no reason to downgrade

常见失败

相信「引擎支持 Web 导出」这句话 —— 支持 ≠ 可用
没测首屏加载 —— 到线上才发现手机上要等 30 秒
忘了存档 —— 用户刷新页面进度没了

Common failures

Believing the phrase "the engine supports web export" — supported is not the same as usable
Not measuring first load — you find out in production that phones wait 30 seconds
Forgetting saves — the player refreshes and loses progress

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