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Re: [css3-transforms] Should rotate3d be listed as a primitive?

From: Dirk Schulze <dschulze@adobe.com>
Date: Mon, 2 Jul 2012 07:46:48 -0700
To: Aryeh Gregor <ayg@aryeh.name>
CC: David Zbarsky <dzbarsky@gmail.com>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <D1C08494-86C9-4B2A-85C5-B45FADD775CC@adobe.com>

On Jul 2, 2012, at 2:52 PM, Aryeh Gregor wrote:

> On Thu, Jun 14, 2012 at 12:17 PM, David Zbarsky <dzbarsky@gmail.com> wrote:
>> Rotate3d is not listed as transform function primitive at
>> http://dev.w3.org/csswg/css3-transforms/#transform-primitives, yet
>> rotate3d(1, 1, 1, 0) is provided as an example of an identity transform
>> function at
>> http://dev.w3.org/csswg/css3-transforms/#TermIdentityTransformFunction
>> Should rotate3d be a primitive?
> 
> Yes, I think so.  Also, probably perspective() should be defined as
> primitive there, although it would have only itself as a derivative,
> because otherwise AFAICT it can't be interpolated.
> 
rotate3d, matrix3d, matrix and perspective are no primitives, nor derivates of primitives.

While we use decomposing for matrix3d and matrix, the problem for rotate3d are the rotation axis that can either be 1 or 0. Matrix decomposing seem to give more predictable results here. Especially when the rotation axis changes.

But rotateX and rotateY seem to be good candidates for primitives on its own, since the rotation axis won't change. I think I just forgot to add them.

I am not sure about perspective. I did not define it as primitive, since (at least some) implementations seem to decompose it as well (maybe because of the use of quaternions?).

Greetings,
Dirk
Received on Monday, 2 July 2012 14:47:28 GMT

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