Additive alfa blending in Verge / Blender?

Hi All,

I am are trying to replicate transparent material with additive blending:
[blending.png]

But we see difference between Blender and Verge export:
[shader.png]
[blender-output.png]
[verge-output.png]

As you can see, we get only black output in Verge.

We have also tried different mapping with alpha channel (not emissive) without luck.

We would like to have additive blending like in first picture. Please can you help me achieve it? I know it was directly in OpenGL drawing settings.

Anyone had luck with additive alfa blending output in Verge, please?

thank you in advance,

Petr from Precismo