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

Re: radial-gradient() proposal

From: Brad Kemper <brad.kemper@gmail.com>
Date: Wed, 4 Nov 2009 22:17:11 -0800
Cc: www-style list <www-style@w3.org>, "Tab Atkins Jr." <jackalmage@gmail.com>, Brendan Kenny <bckenny@gmail.com>
Message-Id: <AA30F294-C8C8-4E2F-B473-0779269C564F@gmail.com>
To: Simon Fraser <smfr@me.com>
[cc'ing my reply to whole list, assuming you meant to do the same...]

I think that clockwise rotation makes total sense when actually  
rotating something, instead of indicating a linear direction. But for  
linear directions, I think that there is not really anything that is  
turning.

Thus using .25turn instead of 90deg for a linear-gradient direction  
feels a little unnatural to me (even though it means the same to CSS),  
because nothing is turning aside from a point of reference. For just  
indication a straight direction, the protractor directions seem most  
intuitive. Like this (showing degrees and radians, and with 0 going to  
the right, and 90 going straight up):

http://en.wikipedia.org/wiki/File:Degree-Radian_Conversion.svg

Here is a Java applet from a math site, which shows directional  
arrows, and the resulting angles:

http://www.mathopenref.com/degrees.html


On Nov 4, 2009, at 7:51 PM, Simon Fraser wrote:

> Unfortunately this gives angles which are backwards from transforms  
> (where positive angles result in clockwise rotation).
>
> Simon
>
> On Nov 4, 2009, at 6:34 pm, Brad Kemper wrote:
>
>> It would if it were degrees of clockwise rotation, instead of just  
>> indicating a linear direction. There is nothing turning here, just  
>> an angle to indicate a straight direction. In geometry convention,  
>> 90 degrees as a linear direction is straight up.
>>
>> On Nov 4, 2009, at 6:14 PM, Brendan Kenny <bckenny@gmail.com> wrote:
>>
>>> Wouldn't 90 degrees point straight down, since +y points down?
>>>
>>> On Wed, Nov 4, 2009 at 8:05 PM, Brad Kemper  
>>> <brad.kemper@gmail.com> wrote:
>>>>
>>>> On Nov 4, 2009, at 5:41 PM, Simon Fraser <smfr@me.com> wrote:
>>>>
>>>>> 0deg being up (I think; the current proposal doesn't say),
>>>>
>>>> 0deg is left-to-right. Like on a protractor, where 0 points to  
>>>> the right,
>>>> 180 points to the left, and 90 points straight up.
>>>>
>



Received on Thursday, 5 November 2009 06:17:55 GMT

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