Re: 2D antialiased graphics using OpenGL

Keith Packard wrote:
> Render exposes glyphs with precomputed opacity values for all three 
> components of the screen.  As glyph hinting (at least today) requires that 
> glyphs be pixel aligned, we can easily precompute the three locations of 
> the glyph corresponding to the three visible components and select the 
> appropriate one on the fly.  I've experimented with shifting glyphs by a 
> sub pixel and the results are quite encouraging:
> 
> 	http://keithp.com/~keithp/subpixel

Hate to be the bearer of bad news, but the "anti-aliased with sub-pixel 
sampling" example isn't. Isn't anti-aliased with sub-pixel sampling, 
that is. If you look at it magnified all the anti-aliasing pixels are 
grey. I went through the samples with xmag because on my LCDs at least, 
sample 2 looks *exactly* like sample 1. I've never seen sub-pixel 
rendering without any colour fringing whatsoever before, and I couldn't 
quite believe it.

>                  But, I think I've demonstrated that really bad text 
> performance doesn't really seem to bother people (current per-component 
> text is drawn in software at around 50000 glyphs/sec)

Depends how bad is bad! The Netscape 4 web font renderer was so slow you 
could watch it redrawing... that was bad.

Incidentally, is there a good reason why an application would use a 
mixture of subpixel and non-subpixel anti-aliasing, or are my KDE 
applications just crackers (or misconfigured)?

Adam Rice