[boost] RE: A preliminary proposal: AGG project

From: Mika Heiskanen (Mika.Heiskanen_at_[hidden])
Date: 2002-05-16 00:41:42

> Two little questions. Is it a common practice to use value 0 for absolut
> opacity and 255 for absolut transparency?
> AGG uses 0.0 for transparency and 1.0 for opacity, i.e. contrariwise.
> What would you prefer?

Both SVG and Java2D define 1.0 completely opaque, 0.0 completely 
transparent. That alone is IMO sufficient reason to choose the same
model.

BTW, I like to pick rational names for attributes like this. Choosing
opacity will naturally imply on for value 1 and off for value 0.
Were the name transparency, I'd again call value 1 on, but the result
would be completely opposite. SVG explicitly uses the name opacity. 
Unfortunately Java2D calls it transparency even though the values don't 
follow the on-off logic.

--> Mika.Heiskanen_at_[hidden]