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Re: Linear gradients, Transforms and angles...

From: Chris Marrin <cmarrin@apple.com>
Date: Tue, 21 Sep 2010 15:53:02 -0700
Cc: www-style list <www-style@w3.org>
Message-id: <E2B171EE-C05C-4EBF-870D-1DB1783FDB6B@apple.com>
To: Brad Kemper <brad.kemper@gmail.com>

On Sep 21, 2010, at 11:21 AM, Brad Kemper wrote:

> 
> On Sep 21, 2010, at 10:31 AM, Chris Marrin <cmarrin@apple.com> wrote:
> 
>> 
>> On Sep 20, 2010, at 7:29 PM, Brad Kemper wrote:
>> 
>>> 
>>> 
>>> On Sep 20, 2010, at 2:01 PM, Chris Marrin <cmarrin@apple.com> wrote:
>>> 
>>>>> This author's expectations are that 90deg should be upward for a linear direction specified in degrees. All my prior experience in life before learning how programmers think reinforce that expectation. 
>>>> 
>>>> Angle is a concept that I believe is fairly new to CSS, so I don't think there is much of a precedent here.
>>> 
>>> Yes, but there is an long-time, pre-CSS precedent for specifying linear directions in the manner printed on traditional protractors.
>> 
>> And there is a long tradition in mathematics of the positive Y axis going up. But in HTML the Y axis goes down, because of the (western) tradition of reading from top to bottom.
> 
> I don't see how that is relevant to traditions of angle-based linear directions. You can still have 0deg=left-to-right and 90deg=bottom-to-top when y++ progresses downward. .

I've gone back and reread the thread: http://lists.w3.org/Archives/Public/www-style/2010Sep/0169.html to try and understand your point of view. It seems that you're simply arguing that the <angle> parameter of the linear-gradient() function should specify counter-clockwise angles, which is what the spec implies today. Fantasai started that thread by asserting that this is contrary to every other use of angle in HTML, which are all clockwise. But the only justification you've provided is the fact that you have a protractor that shows counterclockwise angles. But I have a compass which shows clockwise angles. So which system is better?

I think we have to say that consistency of the technologies in HTML trumps high school geometry.

-----
~Chris
cmarrin@apple.com
Received on Tuesday, 21 September 2010 22:53:35 GMT

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