Hi - I read a post titled “Make light pass through glass in cycles” (now closed) which presents a method for allowing direct light to pass through glass. I tried this method (the “pink” method) and it does let light through but if I have an object inside a lit room and it’s relatively “dark” outside, that object no longer gets reflected in the glass.
Does anyone know how to make glass perform under all lighting conditions where it lets direct light through but as the light outside reduces, you get more reflections internally? Currently if I have to change the glass configuration depending on whether I want to show sunlight coming in (but have no internal reflections even if I wanted them) or want internal reflections but not have any sunlight shining in (even though I want to have both). I would have thought the Cycles Glass BDSF would cope with these different conditions but it seems not (using Blender 2.78). I’m pretty new to Blender so I’m not asking from a great position of knowledge of this subject (which may be evident from my question).
It’s confusing because the “standard” glass node allows ambient light in (allowing you to see objects outside or inside a room) but not direct lamp light. I knowI must be missing something (or a lot!)
It’s supposed to be physical, so you need caustics and shadows enabled. Which I can’t handle, so I make my own custom (sheet) glass material based on this:
Fresnel to mix between transparent and glossy. You need two fresnel nodes, one 1/IOR for backfacing. You only need one if using refraction instead of transparent.
Fresnel output can then be “powered” (say fresnel out ^ 0.5-1.5) for different coating effects which may be present in a building type glass, or fake the effect of multiple layers of glass.
Another mix shader driven by isShadowRay with another transparent shader. If white will remove all shadows from the glass, but this can be controlled to create nice shadows or even some fake caustic effects (real caustics isn’t really a valid option in Cycles).
Thanks for the reply. Would you mind posting a screen shot of the node setup? I’ve since tried a glossy and transparent mixed shader with most of the weighting on the transparency but would like to try your setup.
Posted this a short time ago, but I’ve may have posted others more relevant before. May not be 100% what you’re after but following and previewing the nodes you should be able to follow what is actually going on.