W3C home > Mailing lists > Public > www-svg@w3.org > January 2010

Re: Tangent Angle At A Path Point

From: Andreas Neumann <a.neumann@carto.net>
Date: Thu, 21 Jan 2010 15:29:55 +0100 (CET)
Message-ID: <53931.193.246.86.39.1264084195.squirrel@webmail.carto.net>
To: "Doug Schepers" <schepers@w3.org>
Cc: "Francis Hemsher" <fhemsher@gmail.com>, www-svg@w3.org
+1 for me

I think it would be very useful to have more geometric properties and
methods exposed in the DOM.

Definitely useful for a number of interactive applications or layouts.

Andreas

On Thu, January 21, 2010 3:23 pm, Doug Schepers wrote:
> Hi, Francis-
>
> Francis Hemsher wrote (on 1/20/10 8:21 PM):
>> I could use the tangent angle at various points, or lengths,  along a
>> path. This would be used to both offset and align elements along a
>> path at the same
>> angle as the path at various points(or lengths). e.g.
>> var tangent=myPath.getTangentAtPoint(x,y)
>> or
>> var tangent=myPath.getTangentAtLength(length)
>>
>> Is this possible with current SVG?
>
> I don't believe so.
>
>
>> Also, does anyone else see the need for this as a DOM interface?
>
> I would like to have this, if browsers are willing to implement it.  It
> is useful for all sorts of non-rectilinear layout and custom animation.
>
> Note that the UA needs to have code to do this anyway for textPath and
> animateMotion, it would just be a matter of exposing that code via a DOM
> method.
>
> In general, I think that SVG could benefit from a richer set of
> geometric and graphical methods, in addition to the normal DOM APIs for
> the markup that are applicable to any language.  I think these helper
> methods would also be useful for Canvas.
>
> Here's a few sorts of things it would be nice to have a more complete
> treatment of in the API:
> * vectors
> * matrixes (SVG has a pretty good treatment of these, but could be
> improved)
> * lines
> * angles
> * planes (maybe? could be relevant in pseudo-3D transforms)
> * intersection / collision detection
> * ?
>
> What do people think?
>
> Regards-
> -Doug Schepers
> W3C Team Contact, SVG and WebApps WGs
>
>


-- 
Andreas Neumann
http://www.carto.net/neumann/
http://www.svgopen.org/
Received on Thursday, 21 January 2010 14:30:43 GMT

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