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RE: About arc command

From: David Dailey <ddailey@zoominternet.net>
Date: Thu, 10 May 2012 21:14:42 -0400
To: '向雅' <fyaoxy@gmail.com>, <www-svg@w3.org>
Message-ID: <000001cd2f13$720de610$5629b230$@net>
To be honest, I usually end up trying all four values of the arc-flag and sweep-flag before I remember how they're suppose to work.

Perhaps the example at http://www.w3.org/Graphics/SVG/IG/resources/svgprimer.html#path_A might help.


-----Original Message-----
From: saintofqin@gmail.com [mailto:saintofqin@gmail.com] On Behalf Of ??
Sent: Thursday, May 10, 2012 8:49 PM
To: www-svg@w3.org
Subject: About arc command

I'm doing a svg style implementation.
arcing. check out the document, seems some words not so right:) 1, sweep flag:
I checkout wiki, there is no "positive-angle" speaking. as programmer, I can get,  it just step or delta value >0.
but other users maybe get it better, if other common word used, f.e, counter(anti)-clockwise, or left(right) handle law.
IMO, even "ccw" better than sweep.
2, implnote F.6.5, step4, eval the included angle, the acos result range from 0-PI, but document stats:
where θ1 is fixed in the range −360° < Δθ < 360° Indeed, it misguide me.
Though not use math thing long years, I get back ever feeling at math by bad reviewing the lessons, and send this message.

BTW I hope my english speaking got.
If have some problem, I can send message again with more syntaxed thing.

Received on Friday, 11 May 2012 01:15:17 UTC

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