W3C home > Mailing lists > Public > www-style@w3.org > April 2009

Re: [css3-transitions] Complex easing functions

From: Andrew Fedoniouk <news@terrainformatica.com>
Date: Wed, 08 Apr 2009 20:30:49 -0700
Message-ID: <49DD6BE9.4070403@terrainformatica.com>
To: Dean Jackson <dino@apple.com>
CC: robert@ocallahan.org, Jon Rimmer <jon.rimmer@gmail.com>, www-style@w3.org
Dean Jackson wrote:
> 
> On 09/04/2009, at 12:51 PM, Andrew Fedoniouk wrote:
> 
>> If to relax [0,1] then 'cubic-bezier' value/function [1] has to be 
>> replaced by something else as you may end up with ambiguous curves 
>> that have multiple output values for single input value.
>>
>> http://www.w3.org/TR/css3-animations/#animation-timing-function
> 
> I think we'd just require the function to always have a single output 
> for each input. I'd like to stick with cubics if possible.
> 
> 
> 

How you will enforce that?

And yet it is not clear how exactly that 'cubic-bezier' is defined here:
http://www.w3.org/TR/2009/WD-css3-transitions-20090320/#transition-timing-function_tag

There is a well known cubic-bezier *parametric* formula but it is a 
function of P(t) [1] where 't' is 'time' or 'step' value but not that 
'Input Percentage' as it is shown on the image. In parametric form 
Bezier curves are uniquely determined so you can use them as X(t), Y(t) 
but in Y(x) form Bezier function is ambiguous.

Cheers.

-- 
Andrew Fedoniouk.

http://terrainformatica.com
Received on Thursday, 9 April 2009 03:31:13 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Tuesday, 22 May 2012 03:46:58 GMT