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Re: OT: Need a graphics algorithm

Trygve,

> In a rectangular 24bit RGB pixel field, two areas A & B, both are contiguous
> (no islands), but B is an island within A. Given a point in B, find the
> straight line distance to the nearest point in A... And do it quickly.
>
> What I am ultimately trying to do is antialias the edge of a "blob" (B). I
> figure if I can find the distance to the edge I can just adjust the
> transparency when it gets within 2 pixels or so. Maybe there is a better
> way, but this was my initial thought.

How is B defined, is it a Region (RgnHandle) or a bitmap which can be made
into a region, or are you using core graphics.

If you in QuickDraw, and have a region for B, you could make a copy of it
[C], inset it by your two pixels, subtract is from B [ D = B - C ] and then
use PtInRgn( D ) when you scan you pixels.

You could avoid the region maths using PtInRgn( B ) & !PtInRgn( C ). If you
want varying levels, make multiple inset regions.

Douglas
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References: 
 >OT: Need a graphics algorithm (From: Trygve Inda <email@hidden>)



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