- From: Dean Jackson <dino@apple.com>
- Date: Thu, 26 Mar 2009 08:48:21 +1100
- To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>
- Cc: www-style CSS <www-style@w3.org>
On 26/03/2009, at 6:45 AM, Dean Jackson wrote: > Olaf, > > On 26/03/2009, at 12:49 AM, Dr. Olaf Hoffmann wrote: > >> I think, it is not a good idea, that a matrix is decomposed in an >> (arbitrary) >> set of other transformations for animation purposes, because: [snip your points] >> To resume, I suggest to skip the decomposition idea completely. This >> avoids mathematical problems and paternalism of authors. > > We strongly disagree. We came to this approach for a few reasons: [snip my reply] If you wanted more proof here's an example from the apple engineer who implemented the decomposition: Imagine animating from [0.707 -0.707 0.707 0.707 0 0] to [0.707 0.707 -0.707 0.707 0 0], which is an animation from 45 degrees to -45 degrees. Without decomposition at 50% you have [0.707 0 0 0.707 0 0], which is a rotation of 0 degrees (this is correct) but with a scale of 0.707 (definitely incorrect)? You'd see a box rotate and shrink, then continue rotating and grow again. This would be even worse animating from 0 to 180 degrees, where the box would shrink to nothing at the 50% mark. Dean
Received on Wednesday, 25 March 2009 21:49:10 UTC