Re: Linear gradients, Transforms and angles...

On Sep 21, 2010, at 4:21 PM, David Singer wrote:

> 
> On Sep 21, 2010, at 11:21 , Brad Kemper wrote:
> 
>>> 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. .
>> 
> 
> whoa, the normal expectation is that 0 is the x-axis and that increasing angles move towards the positive Y-axis at 90 degrees (or the appropriate number of radians :-)).

That may be ingrained into your understanding of rotation, but I do not think it is a common way to think of angles as specifiers of linear direction. If someone asks me to draw a 45 degree angle, I draw a line pointing to the right and another line, connected to the first on the left, pointing up and to the right. If superimposed on a square it would go from lower left to upper right corners. When I draw that angle, it never enters my mind which direction the positive y-axis points, and I have no expectation that it matters. I really don't think I am unusual in thinking this way, except perhaps amongst a this crowd.

Received on Wednesday, 22 September 2010 15:03:34 UTC