Dwedit wrote: ↑Sun Jul 10, 2022 1:14 pmCan anyone find some actual examples of art that benefit from *variable* alpha transparency? Not just a fixed level with some opaque parts, but true varying transparency. Not just anti-aliased edges either.
So your hypothetical is that most of the benefit of alpha blending is met by only having 3 levels of alpha? (0, 1, and one in-between blend value.)
I do agree that having only one intermediate alpha level would be pretty versatile and cover a lot of useful cases, probably the majority of them.
A common case where you might want more than one is fading something out, especially if it already has a tranlucent component. Alpha fading is impossible on the SNES... many of the Final Fantasy III/VI summon effects start with an effect that turns the party additive and fades them out, which definitely could have looked better with an alpha fade. They hide it by making the effect fast and kinda blinky.
Otherwise I can think of uses for a gradient alpha. Particle trails which fade to nothing. A creature with long transparent wings. Fog whose density fade across the space of the screen. Magical flames which dwindle toward the tips. Transition wipes and fades. UI overlays could benefit from alpha gradients.
A version of many of these suggestions could be done with additive or subtractive only, but a full alpha blend does widen the possibilities.
Not a reason applicable to SNES, but in 3D stuff I've worked on, we often wanted to avoid alpha blending for particle effects to avoid having to sort the particles back to front. Additive/subtractive blending can be done without sorting.