Unity Techs: Why are you doing this: !(!Math.fround) - WebGL

See here for compatibility:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math/fround

1. IE does not support it.
2. Older versions of browsers don't support it.

Actually, in Unity 5.3, we have changed this condition to always be invoked in Chrome, even though Chrome supports Math.fround. The reason is that we found out that Math.fround is actually:

1. making the code significantly slower in Chrome (instead of faster like in other browsers).
2. making the code use more memory in parsing, which increases the likely hood of crashes at startup time.

 

For reference, here's a bug on Math.fround performance in Chrome: https://code.google.com/p/v8/issues/detail?id=4445

 

Interesting. Do you have a link to your game we could try?

 

This does show the fround version being faster (unlike all our benchmarks).

My guess would be that the difference is in how you disable fround. You override it with a new function. But this is still a function call, which comes with a certain overhead. The way emscripten/Unity disables fround is by actually patching the code to remove any calls to it, which gets rid of that overhead.

 

Yes, it should make the code run faster in Firefox (and does in our benchmarks). It also makes the code match the behavior of floating point numerics of native code better.

 

hi jonas,

in my experience the whole fround replacing in-browser adds up to the load time (which is crucial to us) and often leads to memory peaks and crashes in some browser configurations (*cough* IE! *cough*).

The actual fround-removing is something that could easily be done at build time. Could you please consider making this an option?

I currently take Unity's build output, create a non-fround copy of the JS file post-build and patch everything up with some build scripts, so that the right file is loaded. Although it works, this is tedious and breaks with smallest Unity changes (5.2 to 5.3 for example). A build option in the player settings (like "Prepare optimized JS for IE/Chrome") would be much appreciated and should be fairly easy to do for you.

thanks,
atti

edit:
if anyone could use the C# based method that generates the non-fround js file, poke me.

 

We have considered doing this at build time, but won't do that. Some reasons:

-There is a lot of confusion (check many threads on this forum) about the build size of WebGL builds. Which is why the 5.3 build setup will only emit compressed files, so that when you make a release build in 5.3, you can actually assume that the total size of the download will roughly be the sum of all written files. If we wrote different version of the files, there would again be questions on why the build is so big.

-As for making this an option: I think this whole measure is rather temporary. For IE, you're really out of luck getting any decent results out of WebGL anyways, and that won't change. For Chrome, I do expect that they will fix the performance issues around Math.fround, so patching it out will no longer be needed. I don't want to add an option for what we consider a temporary measure, as it will make it much harder to drop it in the future.

 

Sad to hear, but I get your point (except the "some users can't differ between build size and actually loaded size" thingy)
off to my dirty patch-hacks i go....
thanks!