Ok, I've now done a complete clean install of FS and FSO, and have so far only added the latest media VPs. Using the standard flak, you can clearly see the problem:
http://sectorfiles.net/ti-file-dump/VasudanAdmiral/Pics/BlackBoxBug.jpgWhen you open that exact file (yellow_glow.tga) up in PS, it has no alpha channel at all. This is what I was experiencing with some of my own weapon effects earlier - though they have no alpha channel, they get the black box around them. Taking the entry for the graphic from
"@Laser Bitmap:" and putting it in
"@Laser Glow:" removed the box and all was fine again.
The table entry in question here is the mv_flak-wep.tbm, in the $Pspew section: "+Bitmap: Yellow_glow"
It doesn't appear to be universal however - I just tried it with the mekhu effects - which is another TGA with no alpha map, in the
"@Laser Bitmap:" field. No problems at all. :\ I think it must only appear if the weapon has certain properties. Possibly a trail - I'll try that now.
Edit:Errm, ok. An hour or so more testing, and I think I've been caught out by a few little bugs and mistakes pretending to be a big one. :\
There is a second Yellow_Glow.tga in the maps folder - the one that I think comes as the yellow glowpoint for those glowpointed pofs. Even though this version also lacked an alpha channel, when I deleted it the black box vanished in-game.
The odd bit about this is that I marked the one in the effects folder before I started testing, and checked it appeared in game, to make sure exactly this sort of thing could not possibly be happening, so I have no idea how that can be. :\
The custom effects I was having trouble with also appear to have sorted themselves out - though I don't know how that works either, seeing as I haven't touched them in any way.