Hello,

As far as I can tell, transparency does not work in P3D mode. If this is incorrect, please say so, but all of my tests, as well as a few search hits indicate that transparency does not work. One of those searches indicates that this issue was opened as a ticket on the Lighthouse issue tracker when that was being used, but I don't see any mention of it over here, so thought I would bring it up.

Here are the various posts I found that mention this issue.
quil/quil#156
https://forum.processing.org/one/topic/alpha-value-in-fill-not-working-in-p3d-pjs.html
https://asalga.wordpress.com/category/programming/processing-js/page/4/

Thanks,
Zach