I suspect it is related to the code to decide the rotation of generic, rotatable textures. I suspect it's also probable we'll see it with dirt textures and some kinds of stone, but I've just rushed to get the most easily reproduced example which is only of Netherack and only in the Nether.
I've used Fraps to record a video demonstration of the effect: https://youtu.be/BozurzcfKiI
It's nearly subliminal (and when unexpected in the dark nether, really gives one the heebeejeebees that the ground is shifting beneath your feet. ;P) so a single snapshot can't really communicate much.
But, that said I forgot to leave F3 on for the video so I'll get a separate snapshot of that detail attached as well.
What I expected to happen was...:
That whatever orientation a texture was set to display at the beginning of a scene (eg: a chunk loading) should remain unchanged for me as an observer (even if other players are offered a different rotation) at least until the chunk unloads, or even culls, and then later has to be displayed again. If the rotation never changes under any circumstances due to clever PRNG math then that is probably the safest choice, but the payload is that It should NOT change while I'm looking at it.
What actually happened was...:
Texture rotation jumps, glitches, and changes while I'm looking straight at it.
Steps to Reproduce:
This is just the EASIEST way:
1. Go to nether. Creative mode is just fine to do this.
2. Find a place where you can easily walk or fly towards or from a feature made out of netherack, bonus points if the walls/ceiling/floor around you are also made of netherack
3. Move forwards and backwards as my video demonstrates to invoke the fast and sometimes challenging to consciously spot glitchy rendering behavior.
I have confirmed that the bug triggers sometimes as you change your distance moving towards and away from blocks, but also as lighting recalculations are done. So another very easy way to trigger it is to either begin or end a complex cascade of light-emitting lava. Every time a new block gets or loses it's lava contents in your cascade, many many textures throughout the vertical chunk will flip and glitch about quite regularly.
Posting or removing a torch can cause it, but only for a very brief moment and not every time. Mining a block can even trigger it with the same proviso, most likely due to changing the flood of nearby lighting sources.
2015-11-24: I have now caught an instance of non-grass dirt glitching the same way in the overworld.
Standard Disclaimer: Yes, I know this report is probably a duplicate but after 5 careful keyword searches and reading through over a thousand matches that I'm definitely not a duplicate of, you can't say I didn't give it the old college try before ressing up a new ticket at least. Merging me into the correct stream will be very much appreciated just please don't be too upset with me. 😞
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is duplicated by 6
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Related issue: MC-93052
Can you switch off Mipmapping and tell if that's still happening.
Thank you, I looked for that setting initially and couldn't find it but upon being encouraged to look again I did find it. Unfortunately problem does continue, even the bit about changing with distance, so I've removed all mentions of mipmap that I could find in the ticket description.
I did find a few more (and sometimes even easier) trigger conditions and posted them in the primary description. :3 Put simply: Block updates that alter lighting data seem to do trigger the bug too.
Update again, I stopped a lava cascade off of a high place and then long after the lava had vacated the area wondered about why the textures were still flipping around in the general vicinity on my plateau. I couldn't even look down from any comfortable vantage and confirm any more lava was receding, so it couldn't have been within flood fill distance.
After a minute I found a different perch (looking for how a fortress was situated relative to nearby cliffs) and noticed the receding cascade still very slowly shrinking. Looking up, I could tell every block within ~16 blocks horizontally but even a hundred blocks vertically continued to glitch and shift. Blocks farther than a guestimated 16 horizontal were not shifting (or, at the very least, shifting once or twice per minute instead of once every one or two seconds 😛)
I am uploading 2015-11-22_16.30.18.png which is an F3 on my work laptop. My work laptop does not demonstrate this bug in 15w47c, while my home computer does.
Please let me know if there are any good ideas of data I can try to gather about the difference between these two computers. Both run Windows 7 64 bit, but the affected home computer runs an Nvidia GeForce GTX 650 Titanium while the not-affected work computer runs an ATI Radeon HD 6770M switchable graphics laptop video card with apparently non-upgradeable firmware.
Both should be using precisely the same Minecraft settings since I sync my entire %appdata%\.minecraft folder (among many others) between the two computers in between invocations.
Wish/command, here is my home computer with fully up to date driver (build 359.00), also figured out how to cook a quick animation into a webm instead of leaning on youtube for once:
http://gfycat.com/RepulsiveCoolDoctorfish
Thank you sir. :3
In case it helps, I have posted another video detailing a completely clean and maximum reproducibility test scenario:
https://youtu.be/VJVPfVi4_cw
Following the video instructions you can create identical test world from scratch, or download a save that puts you right at the meat (where you should instantly start seeing some glitching just standing there watching) at the following link: http://lightsecond.com/pub/MC-93167.7z
If this is not enough to bring out any glitching on your system, then I guess you are just not affected after all.
I also noticed during early attempts to record this that when I had many other applications running, enough to lag minecraft, the glitches became much harder to spot. It may benefit you to ensure Minecraft is not competing for resources on your system. Close unneeded processes, and reduce render depth if you must, I have tested with as low as 7 chunk depth so far.
Thank you and good luck. :3
I just added a screenshot from the same area as the youtube demonstration (SMP server) with full F3 information visible.
I've also just created a fresh Creative, Single Player (CSP) 15w47c world and confirmed that the effect happens in the nether there.
THEN I just re-oppened that same world in 15w47b and tried very hard to reproduce the visual glitch, but I could not.
It appears to happen ONLY in 15w47c.