Replaced Google Closure compiler with Terser

[mrdoob]

Giving Terser a try, we can revert if we bump into problems.

This simplifies the build setup so it's all done inside rollup now.
The script also automatically adds the // threejs.org/license header so we won't have to worry about it anymore.

[Mugen87]

Creating three.module.min.js is also straightforward.

Please consider #15176 (comment). I'm afraid the existence of three.module.min.js will cause a lot of issues...

[Mugen87]

Updated the PR so gl constants don't get replaced in non-minified builds.

All users who use a build system will now miss the constant replacement (since they use three.module.js).

[mrdoob]

Please consider #15176 (comment). I'm afraid the existence of three.module.min.js will cause a lot of issues...

Damn. I didn't think of that.
Yes, we can't do this until import maps are available, or we come up with an alternative.

[mrdoob]

All users who use a build system will now miss the constant replacement (since they use three.module.js).

I'll do some measurements to see what filesize savings these provide.

[Mugen87]

I'll do some measurements to see what filesize savings these provide.

Question: Didn't you add the constant replacement primarily for performance reasons? I thought it would be faster to just embed the value instead of looking it up over the gl reference...

[mrdoob]

Question: Didn't you add the constant replacement primarily for performance reasons?

I think the original intent was filesize savings, but performance improvements was a side effect that I forgot. I guess I'll revert that too haha 😅

Although I know that sometimes when debugging your project you find yourself having to look up these constants. But I haven't heard anyone mentioning that recently.

[mrdoob]

Hmm, what a strange thing.

[mrdoob]

Well, that fixed it. I don't even want to know why that happened.

[mrdoob]

@Mugen87 looks good to you?

[Mugen87]

BTW: I've switched to Terser since a while now because of the easier rollup integration and made good experiences 👍 .