# Re: Linear gradients, Transforms and angles...

From: Chris Marrin <cmarrin@apple.com>
Date: Mon, 27 Sep 2010 08:12:41 -0700
Cc: David Singer <singer@apple.com>, Simon Fraser <smfr@me.com>, DanielGlazman <daniel.glazman@disruptive-innovations.com>, "L. DavidBaron" <dbaron@dbaron.org>, "Tab Atkins Jr." <jackalmage@gmail.com>, www-style list <www-style@w3.org>
Message-id: <4EC0F66C-2460-45A9-A9DE-C7A9E9AB5405@apple.com>
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On Sep 26, 2010, at 8:36 PM, Brad Kemper wrote:

>> ...If so, then you must believe "linear direction" is somehow fundamentally different from "rotation" to make the inconsistency reasonable.
>
> Yes. I think most people would consider a linear direction (like "north", "left", "starboard", "up", etc.) to be a single, 2-dimensional direction, and not a rotated anything. Whether you say it as "bottom to top" or "90deg", you are still talking about the same linear (not rotated) direction. The difference is that "90deg" only makes sense if you know what direction zero degrees is (an idea that is totally divorced from the idea of rotating), and which way the other linear directions progress. Those numbered degrees are labels on a circle, as surely as "bottom" and "top" are labels on a rectangle when you say "bottom to top", but can also be subdivided into decimals. .
>
>> II understand the argument, but I disagree with it. If we are trying to make HTML "author friendly" there are many ways to do that. One is to use concepts familiar to authors, so making angles behave in a way that authors are familiar with is a good criteria. But another is to lower the level of knowledge and experience and author needs. And another is to make the concepts consistent. I think having the angle of linear direction and rotations behave the same achieves those last two criteria.
>
> They are not the same, and the behavior is not the same. Only the degree itself is the same; it is just a measure of arc, without direction. We don't treat positive values of "inches" as though the have to go in the same direction for all properties that measure things horizontally. So why should we treat degrees as though they should always be arrayed clockwise, simply because that is the direction for rotations?

Ok, I think we've both stated our positions sufficiently. I still believe the subtlety between the two concepts is too fine for the average author to grasp. But I think we're well into the territory of bikeshedding here, so I'll stop trying to make that point. I'll agree to the consensus on this issue.

-----
~Chris
cmarrin@apple.com
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Received on Monday, 27 September 2010 15:13:16 UTC

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