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Re: Comment on CSS3 angles

From: François REMY <fremycompany_pub@yahoo.fr>
Date: Fri, 29 Aug 2008 10:28:49 +0200
Message-ID: <78AFA41572BE423FA4C6658846C1FAC3@fremycompany>
To: "David Hyatt" <hyatt@apple.com>, "CSS 3 W3C Group" <www-style@w3.org>

I'm not sure I agree with you.

For simple cases like matrix operations, this is not needed.

It's thus simpler for the developers to only have to consider a [0;360[ 
=> When we must transform an angle to a matrix, for a rotation or something 
else, it's easier.
=> When we need to multiply things by a angle, it can be slower if we se 720 
where 360 can works too.

For more complex cases, they are two possibilities :
=> Use another notation to specify complete turns (like: "-xx-animation: 
slow rotation 1t 90°" where1t = 360°, we can have -t)
=> Differency "signed angle" and "unsigned angle"
===> Signed angle are not limited to [0; 360[
===> Unsigned angle are limited to [0; 360[
===> It need a redefinition of each property that use angles to say if the 
property should use signed angle or not.

It's only a proposal, if everybody accept to use only signed angle, my 
remark can be dropped.


From: "David Hyatt" <hyatt@apple.com>
Sent: Friday, August 29, 2008 12:40 AM
To: <www-style@w3.org>
Subject: Comment on CSS3 angles

> http://www.w3.org/TR/css3-values/#angles
> The text says:
> "Angle values should be normalized to the range 0-360deg by the user 
> agent. For example, -10deg and 350deg are equivalent."
> We (Apple) disagree with this wording.  For animated transitions 
> involving rotation, we don't want to normalize angles.  Using the  actual 
> values gives you control over the direction of the rotation  (e.g., if you 
> animate from a larger number to a smaller number or vice  versa).  Not 
> normalizing is also how we're able to do multiple full  spins (e.g., 0 to 
> 720deg lets you animate two full turns).
> dave
> (hyatt@apple.com)
Received on Friday, 29 August 2008 08:29:32 UTC

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