From: Doug Schepers <schepers@w3.org>

Date: Wed, 01 Oct 2008 10:16:18 -0400

Message-ID: <48E38632.2060700@w3.org>

To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>

CC: www-svg@w3.org

Date: Wed, 01 Oct 2008 10:16:18 -0400

Message-ID: <48E38632.2060700@w3.org>

To: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>

CC: www-svg@w3.org

Hi, Dr. Olaf- Thanks for your comment. I've recorded this as ISSUE-2083 in our Tracker, and when we resume telcons next week, after our Test Fest, we will discuss this and get back to you soon. Regards- -Doug Dr. Olaf Hoffmann wrote (on 10/1/08 9:32 AM): > Hello SVG WG, > > > 16.2.7 Paced animation and complex types > notes now for <list-of-points>, that 'There is no defined formula to pace a > list of points. The request to pace should be ignored and the value of linear > used instead.' > This is understandable and fine because > 'Distance is defined for types which can be expressed as a list of values, > where each value is a vector of scalars in an n-dimensional space. For > example, an angle value is a list of one value in a 1-dimensional space > and a color is a list of 1 value in a 3-dimensional space.' > and even more relevant: > "paced > Defines interpolation to produce an even pace of change across the animation. > This is only supported for values that define a linear numeric range, and for > which some notion of "distance" between points can be calculated (e.g. > position, width, height, etc.)." > > And a list is not always a vector (a vector has an absolute value and a > direction) - <list-of-points> - no vector, no formula for a distance, > therefore no paced animation defined in general. And there is no way > to get an interpolation with an even pace for such a list. > > > 1. Surprisingly there are (still) formulas given for <list-of-lengths>, > <list-of-coordinates>, <list-of-numbers>, <path-data>. > These lists are no vectors either, <path-data> is not even a list which can > be confused with a vector. Especially <list-of-points> is equivalent to a > subset of <path-data> - and if the equivalence of a subset of <path-data> > has no formula for a distance as identified already correctly, obviously the > currently given formula for <path-data> results in nonsense and in > general not into an interpolation with an even pace. > The same applies for the other lists, because they do not represent vectors > with one absolute value and one direction. Therefore there should be no > formula too and authors should be discouraged to use calcMode paced with > such types, because if there are already some formulas implemented due to > SVG 1.1 or previous drafts, this will result in nonsense anyway. > > > Note, that the related sample(s) in the test suite need to be fixed/removed > too, for example animate-elem-53 (calcMode paced for points, <list-of-points> > as already excluded in the current draft) > > > 2. transform type scale is pretty fine now (according to the curent formula it > is more one 2-dimensional value, not two 1-dimensional values) as translate > is and skewX/Y. > rotate is more critical, but the new formula is already a big improvement > compared to previous attempts. If the rotation center is not changed within > the animation, this results indeed in a paced animation ;o) > But it should be at least noted for authors, that it exists in general no > paced animation, if the rotation center changes within the animation, > neither with the given formula nor with any other or whatever is already > implemented in previous viewer versions or noted in SVG 1.1. > > > Note, that in the test suite animate-elem-82 describes still the (wrong) > behaviour of SVG 1.1 for paced animateTransform and paced translate > animateTransform is still insensitive to implemented timing and > therefore useless (see long discussion from last year about this test > including a provided alternative). > > > OlafReceived on Wednesday, 1 October 2008 14:16:50 UTC

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