Re: [motion] direction and starting point of circle/ellipse

On Thu, 2015-04-16 at 09:33 +0200, Erik Dahlström wrote:
> Hi,
> 
> forwarding on behalf of Eric Willigers, who found some inconsistencies in  
> how the starting point and direction works in the motion path draft  
> compared to svg2. In the definition of the motion-path[1] property the  
> starting point and direction for circle and ellipse are different to the  
> ones used for the equivalent paths in svg2, see [2][3]. In svg the  
> equivalent path for circle and ellipse starts at 3 o'clock and proceeds  
> clockwise.

The definition of starting point is in SVG 1.1. The direction is a bit
ambiguous but seems to indicate a clock-wise direction. All the browsers
I and Amelia tested follow this convention.[4][5] SVG 2 adds that the
decomposition of a circle/ellipse is four arcs (for the purpose of
marker placement) and makes clear the clock-wise direction.

> Is this going to be a possible cause of confusion, and should these  
> definitions be aligned?
> 
> 
> [1] http://dev.w3.org/fxtf/motion-1/#motion-path-property
> [2] https://svgwg.org/svg2-draft/shapes.html#CircleElement
> [3] https://svgwg.org/svg2-draft/shapes.html#EllipseElement
> 
[4]
https://lists.w3.org/Archives/Public/public-svg-wg/2015AprJun/0006.html
[5]
https://lists.w3.org/Archives/Public/public-svg-wg/2015AprJun/0007.html

Received on Thursday, 16 April 2015 07:53:19 UTC