Re: [ft-devel] smooth update

[Alexei Podtelezhnikov]

On Tue, Sep 29, 2015 at 6:45 AM, Behdad Esfahbod
<address@hidden> wrote:
> Got a new patch?  Can you also summarize what it tries to do?
>

Attached. The original line drawing algorithm bothered me. It
unnecessarily splits the work into scanlines, uses too many divisions,
and works too hard to keep track of remainders towards -Inf. The new
algorithm is faster because it uses only two divisions per line, which
is as good as it gets for smooth rendering (the progression from pixel
to pixel does not itself requite any divisions). There are
limitations. The new algorithm would overflow for lines longer than
32767 pixels in any direction on 32-bit longs, I do not think this is
even practical to reach this limit. On 32-bit systems it will start to
lose smoothness at about 256 pixels, which will probably be noticeable
at about 1000 pixels. Do you have a 4k monitor to test? Is this even
visible? On 64-bit systems the smoothness is lost at millions of
pixels so it is not an issue.

I planned to commit this after 2.6.1 for thorough testing during the
next release cycle.

ftgrays(1).diff
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