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Comment by vvanders | Hacker News Reader

Slick.

Bonus is that Android/iOS is probably just a matter of hooking into just GL, Input & Filesystem APIs.

I'd really love the hear the painpoints of emscripten in production for an actual application. Most of the uses seems to be either games or demos.

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The biggest pain points when using emscripten are debugging, compilation time, and code size. Debugging means poking through what is the JavaScript equivalent of assembly code but without a debugger that understands it (no segfaults on null access, strings are just numbers, etc.). The emscripten toolchain doesn't include an incremental linker yet and compilation time is limited by C++'s dumb compilation model. C++ also generates a lot of code if you use the standard library and templates (this is C++'s fault, not emscripten). In practice, we have an Xcode project hooked up to build the same C++ code and use that as our IDE. That way we can mostly treat emscripten as just a build target. I would only do it if it's worth the tradeoff.

I am currently developing a 3d engine in Emscripten, and to deal with the debugging problem I've developed from the beginning for Windows. The project links with ANGLE to expose GLES2 APIs, and it has both Windows and Emscripten versions of the platform-dependent systems like file access and input. With all this, I spend most of my time in Visual Studio.

Also, for the sake of avoiding complexity, I made a point from the start to never use the STL, and compilation times have stayed nearly instant because of that. Code size is also really tiny when there aren't a million template types floating around.

This comes with the caveat that I'm more comfortable developing without the STL; for other developers or other projects, abandoning the STL may be a tradeoff not worth taking.

mischanix has a good point. Why not whip up a local native version and use that for feature development and debugging? Then you can just do final QA on the emscripten version.

And if it works well enough the native version might be a good option for your power users to get better performance.

We're using Xcode instead of Visual Studio but that's essentially our process. Right now we're focusing our effort on getting the product right on the web first so native is currently on the back burner. A native version will definitely be a good option later on for power users.

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