Mesh Flickering (Modular Tile) (Video Example)

mister_s

I have this issue that has been driving me insane. I have what is essentially modular tiles for the floor on my level. The tiles are just a single planes (2 tris). The problem is the things keep flickering like crazy. I'm not really sure why they are acting like that. They're gigantic, but still have power of two dimensions. They snap to the grid perfectly. (The play area is actually inside an hourglass and on the pedestal it sits, but you can still see down to the floor and it looks awful with the flicker). They weren't scaled in UDK; they were imported in at the necessary size just in case scaling something 200x larger than I made it created any weird problems.

I tried to change the UV to come inward some in case being so close to the edge caused some sort of problem.

I have a replacement that is just a huge floor with the texture tiled on it, but since I spent so much time trying to figure out what the hell is happening I was going to use that as a last resort. I also am not sure if I wanted to do anything special with the tiles yet, so that is why I just made it modular. Plus the level is just a way for me to play around and try to learn a bit more about materials so I'm not to worried about tri count (even though it is still going to be minimal).

The further I get from the floor the worse it gets.

Here are some videos of the problem to help out:

[ame="http://www.youtube.com/watch?v=RJ2ZzNjB3f8"]Mesh Flicker Problem - YouTube[/ame]
[ame="http://www.youtube.com/watch?v=CucZ51Tl5sg"]Mesh Flicker In Game - YouTube[/ame]

I didn't have a microphone handy so there is no audio, sorry. About 3/4 in I scale the grid down to 1 to show everything is snapped correctly.

I don't know if the size or the fact they're just planes have anything to do with it, but I can't figure out why they're behaving like that and I can't find anyone who knows either.

Maybe I'm forgetting something so simple its ridiculous, at least I hope so.

JamesWild

Looks like a driver bug or something to do with occlusion queries; it looks like it happens when the hourglass moves in front of the objects.

ambershee

JamesWild wrote: »

something to do with occlusion queries; it looks like it happens when the hourglass moves in front of the objects.

Indeed - like I said in your UDK forum thread, it looks like an issue with the mesh bounds and it's being occlusion culled.
http://forums.epicgames.com/threads/933423-Flickering-meshes-%28Modular-Floor-Large-Plane-2-tris%29-%28Updated-Now-has-video%29?p=30832097&viewfull=1#post30832097

blankslatejoe

If that's the case you might be able to cheat it into ALWAYS drawing by putting a stray vert or invisible triangle far enough way (in the direction of and past the player) that it creates a bounding box that always encompasses the play area. I think that might force skip of at least some of the queries, right?

Of course, that's a really really really...really... hacky way to deal with the problem. There's more likely some flag on the mesh properties you can flip to deal with this exact situation in a more graceful way.

blankslatejoe

edit -- or give it quick UED collision as per ambershee's comment on the UDK thread and see if that gets it past the occlusion check

mister_s

Thanks for the input everyone. Just an update: adding collision didn't work. A single plane did work, but when I added walls and a ceiling the problem increased exponentially. I even tried a basic brush to no avail. My teacher said he found a discussion that it may be the July build I'm using so I'm going to jump back to March or try November. If that doesn't work then I'm going to just scrap the large level idea. Plus, the walls and ceilings lighting looked atrocious when it wasn't flickering. I didn't look too far into that since the wall flickered.

I will try that idea of adding an actor beyond the distance since I didn't think of that.

Thanks again for the input.

the-blue-turtle

I was searching the forum for help with a similar issue. I'm not 100% sure this is the same problem you're experiencing but I've been having some trouble with modular pieces showing seams in UDK.

The set piece is exactly 512 x 512 generic units in 3ds and it snaps correctly in UDK as far as I can tell but when I have duplicates next to each other I get this weird seam. The asset has custom collision and a second UV channel for lightmap. Any ideas?