Cause of White Sparklies

[Springheel]

I know that z-fighting can cause white sparklies in a map. But are there other possible causes? I have a single room in my map where there are a lot of sparklies running up the corners and along the floor, yet I grid-aligned everything and cannot find any z-fighting faces. Oddly, when I tried to take a screenshot of the area, it came out black. Anyone know of any other causes? The only other case I know of is when models with transparencies intersect something else, but that is not the case here.

[Tels]

I know that z-fighting can cause white sparklies in a map. But are there other possible causes? I have a single room in my map where there are a lot of sparklies running up the corners and along the floor, yet I grid-aligned everything and cannot find any z-fighting faces. Oddly, when I tried to take a screenshot of the area, it came out black. Anyone know of any other causes? The only other case I know of is when models with transparencies intersect something else, but that is not the case here.

 

On my system they are also caused by very long and thin triangles, basically inaccuracies in the graphic cards rendering due to rounding issues.

 

Try "r_showtris 1" (or g_showtris? sorry forgot and see if you get excessive long triangles on worldspawn brushes or intersecting ones on func_statics.

 

Also, sometimes I see them on decals or patches, too.

[greebo]

This can also happen when patches are "sticking into" brushes and their polygons get cut off. But I can't tell whether this is the case here without seeing the actual situation.

[Springheel]

I'll update the map and move the player start right to the problem area so people can have a look.

[Springheel]

Huh, I figured out the cause but I'm not sure why. I had a bright light in an adjacent room, just as a developer lightsource. When I went into F3 mode in DR, it looked like the light was coming through the walls somehow. When I deleted the light, the sparklies went away.

 

Not sure how a light on the opposite side of a wall could cause that, but it seems like it did.

[Fidcal]

I'm thinking more and more we should use thicker walls generally. We know frobbing can take place through thin walls, I've seen torch particle effect tris coming out through the wall of a well-visportalled room, other entities near walls tris showing through and a recent post said light shadow is calculated within the light volume through walls even though it does not actually show. Weren't there some sparklies near the SL church round the corner from that lit lampost? Can't recall if that was solved. Wonder what wall thickness was used commonly in doom?

[Komag]

I have also determined in many cases at least it has a lot to do with lights somehow bleeding through patches or walls or something. In a couple areas I got rid of them by adding solid brushes underneath certain patches to help block the light behind the scenes. But I never got a very definitive consistent understanding of the problem

[Mr Mike]

Patches can certainly act weird, and potentially cause this, if they are too 'concave'. (not sure that's the best expression and I can try explaining if it's not clear)

[Springheel]

There was no patch involved in my case; just a big light behind a wall that somehow bled through.

[Komag]

But you are talking about along a seam, right? So for some reason it doesn't like how the faces are meeting and with the lighting nearby. You might try adjusting the brushes to mitre (or if they do, then NOT to mitre), adjusting thicknesses, or moving light slightly.