[cairo] White seams (lines) appearing between objects

MenTaLguY mental at rydia.net
Mon Jan 14 12:31:22 PST 2008

On Mon, 14 Jan 2008 10:14:36 -0800, Carl Worth <cworth at cworth.org> wrote:
>> In the general case, the fringing is impossible to avoid when using
>> "incremental" antialiasing.  In some specific cases, you can use the
>> SATURATE compositing mode, but it only works when the shapes are
> entirely opaque and/or do not actually overlap anywhere.
> I don't think that's necessarily true.

Yes, I wasn't very precise: SATURATE works fine for overlapping objects
if they are opaque.  There's just no way to make it treat overlapping
translucent objects in a way that conforms to user expectations.

It's probably also worth pointing out that a restriction to 2.5D is
not a big deal in practice: any accumulative drawing API without
z-buffering (like cairo) is inherently 2.5D to begin with.

(FWIW, I realize there may have been some confusion about my intent
in the earlier threads; I'm not concerned with 3D per se.  Instead,
star-and-ring was specifically intended to capture a common use
case for an artist working in 2.5D, where elements are placed adjacent
to one another to give the illusion of a continuous object)


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