Btw VLM works so amazing if look it as Quality/Performance side. Looks like amazing fake GI. Just look how character looks in light environment here and so cheap performance:
But it works like “no warranty”. That what i mean. So I try to explain what happened.
Every release from 4.18 (include betas ‘preview’) until current release i have learned how to reproduce that glitches and i know how they works. Few month ago I knew some methods how to catch glitches and how to avoid (i could explain if need) but its bad way on practice side and pipeline in real projects and still very experimental.
Also a year ago I checked on ‘windows’ builds (last time in 4.23, sure now in windows 4.24 same situation).
I know VLM cells works different than in PIE as well.
Note: I wrote simple plugin (wrap for Engine/LevelStreaming.h) for checking statuses for levels (each level has 7 different states). For me ok if all necessary levels are loaded.
And yea. I never dive to VLM source yet.
Prefer i work on macos, xcode, etc. 16 Gb Ram, tested on mac RX 580 , Vega.
For example this is simplest way for explanation:
Environment static GI is off (off for black), only lights. Cell size is 100 (half of height of character). Memory for bricks 30mb to 250mb. Loaded levels count are 1-3 (one place has 4-5 for tests).
Levels with different scenarios (SL, LM importance, VLM density volumes sizes; light type and light count; volumes overlaps; and etc. for tests):
Note: Yellow boxes are “Streaming Level Volumes”
Catched glitches on character looks like on this 4 screenshots:
And last levels (5-b,5-1,5-2) where VLM stop works:
Cells representation absent even do another levels are off in Editor. (limitations?)
Note1: Levels in list not sorted properly by engine (created or added later).
Note2: Each level in build has few simple geometry. Build size is 220 mb (20 levels of geometry, static lightmap data etc - around 50-60 mb of data for all levels). So levels load and unload very fast.
Sometimes if move around glitch area 30-40m a minute then glitch will gone (depends how far you go and back repeatedly). Magic?
Its just few examples. I discovered tens strange situations specially for VLM.
So if need more information about how bugs and glitches “works” in VLM i could explain more and more methods. Maybe it will help to make it perfect feature.
Example project video:
0:42 - how to glitches gone if load and unload previous level !
2:00 - another glitch but still bcoz no levels operations
3:14 - glitch and later it gone again (next level loaded/unloaded operations through LSV)
4:42 - black hole (no levels operations, just something happends)
6:18 - good example how it gone
10:54 - VLM cells stop working. No GI …
Note: 7 moments timestamped in description of this video on youtube. If rebuild light in project , count of situations various 5-15 and in another places of levels.