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[ft-devel] The FreeType rasterizer

From: RepSTOSW
Subject: [ft-devel] The FreeType rasterizer
Date: Wed, 9 Jan 2008 08:33:07 -0800 (PST)

Good evening!

I hope this is the right place to post my questions regarding the FreeType
rasterizer :)

I have been reading up on the rasterizer, and it seems pretty solid. I must
admit that I have some problems making out exactly what the code does
though, so most of my conclusions are from the documentation.

As I understand it, curve (and straight) segments are subdivided (more or
less) until they cover only one scanline. Then it's determined where the
scanline is actually intersected by the line, and thus we can know the gray
scale of that particular pixel on that particular scanline. (Am I on the
right track so far?)

The thing is that I can see how this works for a two pass algorithm, where
both vertical and horizontal scalines are evaluated against the outlines. It
says, though, in the documentation that this is a one pass algorithm so my
main questions is: How is the rasterizer able to produce more than one gray
pixel per scanline and line? How will nearly horizontal lines handled? Won't
they get a single gray pixel only where the line crosses the scanline? What
am I missing here?

I could perhaps post an illustration of what I mean if the above description
is unclear.

I'm thankful for any help on this, even if you don't know the exact answer,
you might have a better clue of how this might work than I do.

Thanks in advance!
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