Refraction with transparent background

I’m using refraction in a scene with a transparent background, but the transparent parts are turning gray. How can I make the material use the alpha channel of the render texture

cc @sebavan

you need the background to be rendered in the rtt, the alpha within should not be used for this purpose.

Even if we were using the alpha what color would you put inside ?

In Blender, when I set the option to “transparent,” I can still make the parts where refraction doesn’t appear transparent. I think we can achieve this as well since RTT has an alpha channel. We can use this value as the alpha value for the fragment output.

when you use a refraction texture, the rendering is Opaque in the pbr material.