This is a new glass that I made specifically because you brought up the issue of shadows.

I normally use Reflection + Refraction. But Poser doesn't understand that something should let light pass through unless you use Transparency. It doesn't examine the Refraction_Value like it should.

This is fine for flat, thin glass, because such glass does not appreciably bend the light anyway. So I came up with a way to do the Reflection + Transparency.

You still want to use a Fresnel effect (amount of Reflection varies with viewing angle, and Reflection + Transpareny = 1). Turns out if you plug your Reflect node into Reflection_Color, Poser doesn't do the conservation of energy thing for you. But I found if you plug it into Diffuse_Value instead, it does. Hehehe.

The double shadow was a failure - not intentional. I wanted to use a directional light in addition to the IBL because the sky actually does cast a vary diffuse amount of direction light when screened by a window. But the 2 point light trick didn't work. A wall near a window is brighter near the window and that's what I'm trying to do. IBL won't do that.

I'll find a way. Like I said, I think a large array of point lights would work.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)