Then it turned out that if I scaled it down, vertices started jiggling around (if I move the camera, they start jumping, as if some sort of decimation modifier is there but there is none).
I tried creating a new file and scaling down the subdivided mesh but it was perfectly fine until I added this problematic object from the initial scene. After adding, all meshes start behaving like that (vertices jiggle). Also, I’ve checked many different things like UVs, double verts, applying transforms, removing material, fixing normals, changing scene unit scale and swapping to CPU render, that’s all that I remember but there was more.
I’d be happy to hear from you
If you need a bit more explanation - feel free to ask
That’s an issue with viewport display, I encounter it quite a bit with real scale objects which are small. What I tend to do in that instance is, for modelling purposes, scale it by 10 or 20 times, do the work, then scale back to real-world one I’ve finished.
The triangulated thing is a shading issue given the geometry of the object. The geo on that is very messy, (I’m guessing an imported object), that is never going to look good.
Personally, I’d rebuild that as it’s pretty much unusable as it is, you could build that in a few minutes.
It’s my own model from another project and sure it’s easy to remodel from scratch but the thing is that every object in this scene seems to behave like that
That looks like a precision issue happening with very small models. Make sure your object sizes are sane (not in micrometers) and scene scale is 1. If you need smaller objects, model them bigger (10x or 100x) and scale them down (0.1x or 0.01x) in object mode.
You need to clean up your mesh…
You could try to use the Smooth modifier, or do some relaxation in Edit mode, or use some addon to help the process (looptools, polyquilt, etc)…
But i believe @colkai suggestion to rebuild the object completly is the best solution.
Look here. Do you think that I haven’t tried that? And the topology of the initial bottle model is ok. It is not perfect but not bad enough for it to create some artefacts. I’m sure it’s because of some setting in this particular scene
P.S.
I can’t send multiple images at once, so I had to combine them together.
1st is an old bottle model and 2-3 are screenshots of new objects with stock glass shader and perfect topology. Btw transparency bounces are set to 30
sure, it was 1st or 2ng thing I’ve thought of. I even wrote it in the starting message. I haven’t encountered something like this in 2 years of 3D
Here it is so you believe me
