Comments on: Callout for HELP! How do I produce good art for Additive blending?

By: Sharky

Sharky — Wed, 04 Jul 2007 08:52:32 +0000

Thanks.

Looking forward to giving these ideas a try.

By: Eivind

Eivind — Wed, 27 Jun 2007 16:58:40 +0000

I support Pekuja’s idea of using a “subratctive” technique but I am curious if you have to turn the expression the other way around to: 1 – (source_color + destination_color)? That way as the result of adding source_color and destination_color gets brighter the end result will diverge towards 0 (dark).

It would be interesting to see some example code on this.
Air Legends sounds really interesting, will have to try it out when I get home!

By: Sharky

Sharky — Thu, 21 Jun 2007 22:25:36 +0000

I think I tried that, but I’ll have another go. From memory things tended to lose their nice colors.

Are there any techniques to employ with the Alpha channel for Additive blending?

For instance, should any of the Alpha channel be 100% opaque? In the end I suppose it’s always going to depend on the result you want.

I want my Explosions to be fairly Opaque, but I still want the colors to be rich.

By: Anxiety

Anxiety — Thu, 21 Jun 2007 15:55:36 +0000

Just make your source images dimmer.

By: Sharky

Sharky — Thu, 21 Jun 2007 11:18:41 +0000

Hmmm… I hadn’t thought of that. Additive, but not additive. Subtractive!

Thanks Pekuja.

By: Pekuja

Pekuja — Thu, 21 Jun 2007 09:41:18 +0000

Now I don’t really know much about additive blending, but if you wanted your smoke to get darker as it thickens, shouldn’t you be doing the additive blending in reverse? I think the formula would be:
source_color + destination_color – 1.0
where the colors are in the range [0..1] . So then use bright gray textures… dunno if that produces good results, but I think it’s worth a try.
Also, a lot of photo editing tools like Photoshop or Gimp allow you to blend layers additively, so you could use that to play around and find what works.