Godot: Viewport display modes not working in GLES 2

[hjsrabi]

Godot version:

3.1

OS/device including version:

Pop OS 18.10/ NVIDIA GeForce 920MX

Issue description:

when you try to change the viewport render mode to something like wireframe with the gles 2 renderer nothing happens

when i tried it in gles 3 it worked fine

Steps to reproduce:
create a new project
switch to gles 2
add a mesh instance
change the viewport display mode to wireframe, overdraw, unshaded.

[clayjohn]

Yes. This is a known bug. It was reported here. https://github.com/godotengine/godot/issues/26406. Although you explain it much better. :)

[Toshiwoz]

I'm working on a project that relies on gles2.0 would be great to have it fixed.
Is wireframe not possible because of some limitations on this version of the graphic library?

[clayjohn]

@Toshiwoz It just hasn't been done yet! It is a lot of work.

[CarlGustavAlbertDwarfsteinYung]

I can confirm only Normal works.

Note that Orthogonal doesn't work either in GLES2 editor viewport. It just displays everything as clear color.