Decal issue

[ungoliant]

not sure if this is a known bug, or a problem on my end, (couldn't find a tracked entry for it) but i'm getting some nasty decal glitch.

 

it seems that other patches or models placed in front of some dirt/stain decals will still show the decal behind it if the player moves a certain distance away. Then when the player moves in closer, the decal stops showing through. Gives an extremely ugly "popping" effect like a bad LOD system.

[Baddcog]

yeah, i've been getting this too. I think it's the z fighting issue the door hinges had.

 

I was running around StAlban yesterday and it was real noticeable with the grime on the torches, however they seemed to be away from the wall a bit (so they'd z-fight with the torch base)

 

not really Z fighting though, just 'it's in back' , move a few feet, 'it's now in front'.

 

Also have this in my city mission, a decal behind some fun_static patch arches. at a distance of about 400 units the decal appears in front of the 16 unit thick arches, that's a big jump.

 

Been trying to pin it down specifically, maybe it's just a patch bug - z order thing.

[Bikerdude]

fyi I have been getting it and I thought I logged a bug trackers for it, but in case i havent, Ungoliant should log one.

[ungoliant]

wow, i totally stumbled on the source of the bug while browsing iddevnet. Ok so heres the deal. Any decal using DECAL_MACRO is by definition using polygonOffset 1, described on iddevnet as such: "offset the depth buffer to combat z-fighting".

 

After removing DECAL_MACRO from one of the shaders i was using, the bug was fixed, and to confirm, i re-applyed polygonOffset 1 and the bug showed back up again. So there it is.

 

On another note i think i've solved another bug at the same time. When i took off DECAL_MACRO, any time selecting a patch with that texture applied, it became transparent in DR, so theres the transparency bug identified too.

 

Downside: haven't checked to confirm yet, but i suspect that removal of DECAL_MACRO will result in z-fighting on decals that are flush to the surface of brushes.

 

edit: actually i guess by the way its described in iddevnet, its not really a bug at all. This might also heavily influence some discussion i read about wanting decals to default either flush or offset from brushes when using the "create decals for selected faces" function.

Edited October 14, 2010 by ungoliant

[Bikerdude]

edit: actually i guess by the way its described in iddevnet, its not really a bug at all. This might also heavily influence some discussion i read about wanting decals to default either flush or offset from brushes when using the "create decals for selected faces" function.

Well i for one have alwayes wanted decals to be offset by 1 grid at @0.0125, that way i can select the decal rather than the brush etc.. btw fids that double click approach dont work.

[Baddcog]

I always just hide brushes, select decal, kindof a pain but...

 

Yeah, that macro thing will probably cause z-fighting, most likely at larger distances. So it's either z-fighting or the decal overriding polys, or an offset which can look odd up close in corners (you can see a strip of 'clean' behind the dirt).

 

Not sure which is best imo. decals are best looking flush than offset, but if offset is the only way to prevent z-fighting AND polygon offset, then the decal offset is probably the lesser of 2 evils.

Though we can't change existing decals as it will break older maps and make them z-fight.

 

So now we need a naming scheme... something to let mappers know which is which...