The transparency (alpha and bkalpha) works file with pyFormex but when exporting to webGL and visualizing on a web browser the alpha and bkalpha are not ok. This is due to the faces.opacity in the .js file which over-rule the back.opacity and front.opacity.
By just commenting this faces.opacity, front.opacity (alpha) and back.opacity (bkalpha) work fine!

object_59_back.opacity 0.7
..
object_59_front.opacity 0.2
..
object_59_faces.opacity = 1.0;

Could this be fixed when exporting webGL from pyFormex GUI?

It works nice with surfaces but lines (and edges) cannot be correctly visualized. Lines are also wrong when switching a surface mesh to wireframe mode (even without transparency).
Does it happen also to you guys?

This was until now impossible to do, because our renderer draws both front and back sides of the triangles. There were two reasons for this: enable different back and front side color, and remove some artefacts that we were not able to eliminate in an other way. Because of this double drawing, it makes no sense to use different alphas, as both values are drawn in each case.

However, in commit 782d5c8 we have changed the shaders so that triangles with normal oriented away from the camera are discarded,
and thus far we have not seen any artefacts reappearing because of the change.
This will make it possible to introduce different front and back opacity.