Addendum…you need to count the liquid, too…so add at least one, preferably 2 to that…so you should be at 4, at least…6 is better (it’s always better to have a couple of extra ‘slots’ in the depth, for unexpected ‘bounces’)...actually add 3. There’s going to be an interaction between the glass and the liquid, too (at least as far as reflections).
Make sure the IOR setting (Index of Refraction) is ‘right’ for what you are rendering,or at least close…leaving it at 1 or 1.30 or whatever is the ‘default’ doesn’t work (1 is the IOR of air and 1.33 is that of water). And yes a 0.01 difference can be noticeable, depending on the render/render settings.
Here’s a pretty comprehensive IOR table… http://www.pixelandpoly.com/ior.html
Wine is not on that list…but it is somewhere around 1.35-1.37 and the wine glass, assuming it is ‘crystal’ should be around 1.57.
As to things to reflect…well, obviously, the hand holding the glass is going to provide ‘something’...but what Jaderail is talking about is a ‘complete’ environment. No ‘ground plane’ or ceiling/walls/floor or ‘skydome’ and you can end up with odd spots or really wacky reflections. If you can’t provide that, faking it by plugging a reflection map into the reflection color can work, too.
Another thing for ‘realistic’ glass…the glass item needs to be modelled extremely cleanly and properly. There can be NO intersecting faces in it or it won’t EVER render like glass. Also it CANNOT be ‘single thickness’...it MUST have a clearly ‘two sided’ mesh. Also, for best results, the liquid needs to be separate mesh that just touches (actually is the tiniest fraction of a mm away from) the inside of the glass, without intersecting (some renderers/materials/shaders can handle the setup for that without it), but it can never just be a simple plane across the top or something like that.
Just from the looks of it, that glass is pushing the envelope on the mesh front…there’s some really odd modelling there…
The first image is an example without a ‘complete’ environment.
The second adds a skydome.
The third…an example of a ‘proper’ glass shader…(the only thing it isn’t doing is caustics) and yes, shadows are too ‘hard’...that was my fault, I didn’t set ‘soft shadows’ on the light…
All three of those are 3Delight renders…actually they are probably DS3 renders (the date they were made is about the time DS4 Pro was made a ‘limited time’ freebie). I can’t remember the exact light setup…but it wasn’t Uber…and the shader is a personal build, that I should probably go ahead and release and not worry about getting caustics working the way I want them to. On the third pic, you’ll notice a bright spot on the glass…in line from that, on the table, if caustics were working, would be a nice play of light, in the shadow of the glass.
(I believe that it’s just a simple spot/distant light combo…)