- From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
- Date: Thu, 26 Jun 2008 11:46:16 +0200
- To: www-svg@w3.org
I think, the missing arc commands are more related to a tiny profile than to version 1.2, because they are not available in SVG tiny 1.1 too: http://www.w3.org/TR/SVGMobile/#sec-shapes As many other shapes elliptical arcs cannot be exactly expressed with cubic curves. Depending on the accuracy requirements, an author can compute a set of cubic curve fragments to replace an elliptical arc approximately. Typically a good approach is to demand that position and derivates fit together at the end of cubic curve fragments joined together to an approximation of an elliptical arc. How many curve fragments are needed to get the desired accuracy obviously depends on the requirements of the author, therefore there cannot be a general rule to do this approximation. However, the rule described above is an even more general rule how to approximate any continuously differentiable curve with a cubic curve, but this needs some calculations, either analytical or numerical. I needed for some reasons already a cubic curve replacement for an ellipse, circle and some other shapes like spirals, atomic transition dipole moment shapes, therefore I already did this with a small PHP script analytically or numerically and it is not really a big issue if one is familiar with basic analytics.
Received on Thursday, 26 June 2008 09:48:36 UTC