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[csswg-drafts] [css-transforms] Spec doesn't actually define perspective(0), and behavior is crazy anyway

From: Tab Atkins Jr. via GitHub <sysbot+gh@w3.org>
Date: Wed, 11 Jan 2017 20:07:12 +0000
To: public-css-archive@w3.org
Message-ID: <issues.opened-200194232-1484165231-sysbot+gh@w3.org>
tabatkins has just created a new issue for 
https://github.com/w3c/csswg-drafts:

== [css-transforms] Spec doesn't actually define perspective(0), and 
behavior is crazy anyway ==
The definition of perspective(n) creates a 4x4 matrix with a component
 equal to 1/n. At 0 there's a 1/0 in the formula, so clearly this case
 isn't actually defined.

Edge and WebKit/Blink treat perspective(0) as perspective(inf) (that 
is, it's an identity transform). This is discontinuous with 
perspective(small).  Firefox rejects perspective(0) at the grammar 
level.

In transitions, Blink/WebKit currently transition by converting the 
perspective(0) into an identity matrix and interpolating that way, so 
you don't see a discontinuity.  This will change when impls match the 
new spec change (agreed in the f2f) that perspective() animates *as* a
 perspective() function.

Please view or discuss this issue at 
https://github.com/w3c/csswg-drafts/issues/886 using your GitHub 
account
Received on Wednesday, 11 January 2017 20:07:18 UTC

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