From: Dean Jackson <dean.jackson@cmis.csiro.au>

Date: Wed, 21 Jun 2000 12:24:41 +1000

Message-ID: <39502769.8832EA3C@cmis.csiro.au>

To: Burton Radons <loth@pacificcoast.net>

CC: www-svg@w3.org

Date: Wed, 21 Jun 2000 12:24:41 +1000

Message-ID: <39502769.8832EA3C@cmis.csiro.au>

To: Burton Radons <loth@pacificcoast.net>

CC: www-svg@w3.org

Burton Radons wrote: > > I see from the archives what fill-rule:evenodd; is supposed to do, but > nonzero (Which is used in the Adobe Illustrator exports, such as the > Mozilla example) is a cipher. Is it as with TrueType, where clockwise > lines add one to a count and counterclockwise subtract one, and positive > values are fill, or is it another algorithm? Hi Burton, The latest public working draft (3rd March 2000) doesn't have a description of fill-rule. The next public release will probably say something like this: evenodd This rule determines the "insideness" of a point on the canvas by drawing a ray from that point to infinity in any direction and counting the number of path segments from the given shape that the ray crosses. If this number is odd, the point is inside; if even, the point is outside. nonzero This rule determines the "insideness" of a point on the canvas by drawing a ray from that point to infinity in any direction and then examining the places where a segment of the shape crosses the ray. Starting with a count of zero, add one each time a path segment crosses the ray from left to right and subtract one each time a path segment crosses the ray from right to left. After counting the crossings, if the result is zero then the point is outside the path. Otherwise, it is inside. There will probably also be illustrations of the two rules. The Adobe, CSIRO and IBM implementations process fill-rule correctly, so you could make your own examples if you can't wait for the next public draft. DeanReceived on Tuesday, 20 June 2000 22:24:26 UTC

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