Black + Additive =/= Transparent

[Tormentor667]

I noticed this already several times and I think this can be considered as a bug, even though I do not know how the software renderer actually handles things.

If you have a black texture and apply the TranslucentLine special to a 2-sided wall using that black texture, additive translucency should actually make the black parts completely invisible. Though for some reason they "darken" what's behind them (about 5-10%).

Here is a little example:


These "steam" sprites consist of white circles on a totally black background. For some reason you can actually see this black background.

[esselfortium]

If I remember right, this has been reported before and is a known precision issue. It'd be much slower to do it "right". The solution is to just use actual transparency to replace the offending dark colors in your additive sprites/textures.

[Blzut3]

What esselfortium said.

http://forum.zdoom.org/viewtopic.php?f= ... 7&p=505269

[Graf Zahl]

Never *EVER* use black for transparency in additive sprites. It doesn't work right. Cheat yourself some invulnerability and watch the wonderful rectangles around the smoke!

[Tormentor667]

I could also use alpha channels but the problem is that this doesn't work fine when I want to use translations as well. If I want to have a sfx in 5 different colors, I do need 5 different sets of sprites

[Graf Zahl]

If you want to use translations you have to use Doom patch format. If you use that you already got your transparent color, so where's the problem?

[Xaser]

The problem is that it doesn't happen to just black (#000000), but to any other color that's sufficiently dark enough. That means that in order to work around this, a couple more shades of dark have to be removed (resulting in a not-quite-smooth fade to translucent in GL).

Not that it's a huge deal, mind you, but that just goes to say that this still happens in cases where transparency is correctly applied to the outside sprite edges.

[Tormentor667]

That's exactly the problem that I run into in the above screenshot.