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[css3-2d-transforms] rotation and animation

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Mon, 23 Mar 2009 15:32:45 +0100
To: www-style@w3.org
Message-Id: <200903231532.45533.Dr.O.Hoffmann@gmx.de>
Hello,

this comment applies to css3-3d-transforms as well.
http://www.w3.org/TR/2009/WD-css3-2d-transforms-20090320/#animation
http://www.w3.org/TR/2009/WD-css3-3d-transforms-20090320/#animation


In the related section about the transformation functions it is noted, that
for the <angle> type CSS Values and Units apply:
http://www.w3.org/TR/css3-values/#angles
This notes:
"Angle values should be normalized to the range 0-360deg 
by the user agent."

For static displays this might be useful, but for animation, 
1) it does not note, whether the borders of the range are
included or not or one included and the other excluded, 
what can result in a big difference for an animation from
0deg to 360deg.
2) authors might want to have a rotation from 30deg to 750deg,
what means two complete turns and not no animation, 
or maybe from 90deg to -90deg, what is different from an
animation from  90deg to 270deg (what has a 
different rotation direction too).
Concerning animation I think, it is pretty useful not to
modify the given values because this results in quite
different effects as typically intended by the author,
respectively authors cannot get the intended animation
effect with only one rotation function at all.

Best wishes 

Olaf
Received on Monday, 23 March 2009 14:36:28 GMT

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