Bad webgl alpha config for 3-D scenes

[archmoj]

Noticed blending issues (see the yellow areas on the image below) with Ubuntu + FireFox.
This could be related to premultipliedAlpha: true instead of false.
See gl-plot3d at https://github.com/gl-vis/gl-plot3d/blob/ccfc4318ec9d382900f7b80b17b1630092fe3953/scene.js#L84.

[archmoj]

Also this mock renders:

[archmoj]

Also observed on
Windows 10 + Firefox 64 - 69.
Windows 7 + Firefox 69.
So the proposed fix may help!
But because the quality of rendering won't be great on other browsers namely Chrome (see the bottom image) it looks we should spend more time on this before making a PR.

[archmoj]

By the way here is the codepen used to test the bug as well as possible impacts of the fix.

[archmoj]

See #4334 (comment) which illustrate a similar issue on Chrome.

[gvwilson]

Hi - this issue has been sitting for a while, so as part of our effort to tidy up our public repositories I'm going to close it. If it's still a concern, we'd be grateful if you could open a new issue (with a short reproducible example if appropriate) so that we can add it to our stack. Cheers - @gvwilson