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Re: [web-animations] no 'add' in iteration composite operations

From: Brian Birtles <bbirtles@mozilla.com>
Date: Thu, 09 Apr 2015 15:26:38 +0900
Message-ID: <55261B9E.3020609@mozilla.com>
To: Aleksei Semenov <a.semenov@unipro.ru>, "public-fx@w3.org" <public-fx@w3.org>
CC: "dom@unipro.ru" <dom@unipro.ru>
On 2015/03/03 19:35, Aleksei Semenov wrote:
> Hello, everyone.
>
> It looks strange, that iteration composite operation
> ( https://w3c.github.io/web-animations/#iteration-composite-operation )
> defines only two operations: replace and accumulate.
> While there are three operations for animation composition:
> replace, add and accumulate. (
> https://w3c.github.io/web-animations/#animation-composition )
> Could you explain why 'add' is excluded?
> Is it typo or there is some reason?

The main problem I remember with allowing 'add' when repeating is that 
when add is defined as something like "append to the end of the list" 
the resulting value would quickly get out of hand.

For example, for filter lists, if we have:

  Va:  blur(2)
  Vb:  blur(2)

'accumulate' gives:

  Vresult:  blur(4)

But 'add' gives:

  Vresult:  blur(2) blur(2)

If you've got a quickly repeating animation you can see how 'add' 
quickly gets out of hand by creating a really really long list.

I think we might have also run through some examples to see which was 
more useful and decided 'accumulate' was what you wanted when repeating 
but I can't find the details of that right now.

Best regards,

Brian
Received on Thursday, 9 April 2015 06:35:15 UTC

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