Glass Shadows Cycles

[moony]

Every room does have windows - but why do you have to use the glass BDSF for those?

What additional realism does having refraction on a flat piece of glass give you that a glossy/transparent mix does not?

Like I said - the workarounds are so trivial, what advantage would adding this by default to the glass BDSF bring other than saving you perhaps a couple of seconds of work?

The glass BDSF has other, more serious issues IMO. For example, if you give it a colour (e.g. red), the reflections also become red. This is not accurate for a dielectric material where reflections should be the colour of the incident light.

You are far better off using a glossy/refraction mix with a fresnel term in order to get colour correct reflections as demonstrated in this thread:

Which faux glass node setup is better?

You need to expand the question. What application is it for. The solution for a glass vase with transparent shadows is different to that for architectural glass panels for the side of a building for example. No single solution is the best - it depends on the application. For architectural glass panels for example (particularly for windows) I probably wouldn’t use the glass shader at all, preferring instead to have a Fresnel mix of glossy and transparent shaders. [glass2] If I wanted colou…

Cycles shader nodes are tools in a toolbox - they are not (for the most part) a complete solution by themselves. You should use an appropriate combination of tools to complete the job.