THREE.MathUtils: added seededRandom() method

[WestLangley]

This is useful in generating repeatable results in an existing example.

THREE.Math.prng( 123 );

Math.random = THREE.Math.prng;

[Mugen87]

Similar code was removed from the examples here: #16576

And now you want to add it to the core? Um, does not seem logic to me...

[WestLangley]

@Mugen87 If you don't want users of the library to have access to this method, I'll close this.

[Mugen87]

No offense, I'm just irritated by the PR. I think we made a decision in #16576 to not add such code to the lib.

Anyway, I don't feel strong about this. If you think it's a valuable addition, I won't block it.

[WestLangley]

No offense, I'm just irritated by the PR

Please don't be. I was not intending to annoy you. I thought I was doing what you suggested when you said:

Okay, if @mrdoob wants to keep PRNG, I suggest to move it into the THREE namespace and the file to the math directory.

But I guess you were suggesting to move it to examples/js/math...

We can do that, merge this, or close this. I don't care.

[Mugen87]

Yeah, in this sentence I was referring to examples/js/math^^. Anyway, since PRNG.js is now gone, I would only add it back if there is an actual user request.

[mrdoob]

Seems like this was a misunderstanding. @Mugen87 suggested adding PRNG in the THREE namespace so we can generate the JSM version automatically.

[Mugen87]

I actually wanted to remove PRNG.js in the first place since it was not used in the repo^^. So I think the status quo is okay now.

[WestLangley]

Trying again...

[mrdoob]

We just need a compelling use case.

[munrocket]

var x = crypto.getRandomValues( new Uint32Array(1) )[0] / 0xFFFFFFFF;

Should work in any browser with webgl. Performance only twice worse, because it’s cryptography safe PRNG and supports an arrays.

[WestLangley]

Closing again...

[mrdoob]

@WestLangley can we call this MahtUtils.deterministicRandom()?

[mrdoob]

Oh, can't reopen the PR because the branch is gone.

[WestLangley]

can we call this MathUtils.deterministicRandom()?

@mrdoob Maybe MathUtils.seededRandom() or .seedRandom()?

Similar nomenclature is used here: https://github.com/davidbau/seedrandom

[mrdoob]

Hmm, seedRandom() is shorter... I have no preference, as long as is not an acronym.

[mrdoob]

Actually, I think seededRandom() sounds better.

[mrdoob]

Thanks!

[wrightwriter]

This function expects big numbers, otherwise it results in a very biased distribution.
I think this warrants a comment, explaining it, no?