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[SMIL30 LC comment] 3.9 SplineAnimation Module

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Tue, 14 Aug 2007 16:05:05 +0200
To: www-smil@w3.org
Message-Id: <200708141605.05886.Dr.O.Hoffmann@gmx.de>

Hello SMIL working group,

some comments on the SplineAnimation Module:

3.9.1 SMIL 3.0 SplineAnimation Module Attributes

'Discrete animation can be used with keyTimes, as in the following example:
<animateColor attributeName="color" dur="10s" calcMode="discrete"
     values="green; yellow; red" keyTimes="0.0; 0.5; 0.8" />

The value of the "color" attribute will be set to green for 5 seconds, and
then to yellow for 3 seconds, and then will remain red for the remainder 
of the element.'

--> 'the remainder of the animation'?
or 'for the last 2 seconds of the animation'? because there is no 
fill="freeze" ...?


'<par dur="30">
  <animate calcMode="discrete" repeatCount="2" dur="10" fill="freeze"
    accumulate="[as specified]" keyTimes="0.0; 0.5; 1.0" values="0; 1; 2"/>

required attributeName is missing...
reference definition of par...


3.9.4 The spline animateMotion element


Support includes commands to describes lines ...'

-> '... to describe lines ...'?

'When a path attribute is used, the number of values is defined to be 
the number of points defined by the path, unless there are "move to" 
commands within the path. A "move to" command does not define an 
additional "segment" for the purposes of timing or interpolation. 
A "move to" command does not count as an additional point when 
dividing up the duration.'

-> Except the first M/m command, else even with the simplest
paths there are problems:
path="M 0 0L1 1"
This is the same as values="0 0;1 1",
therefore 2 values, one segment. 
Formally the first M/m command is both - at the beginning and
within too, because it is not outside of the path.

-> maybe useful to mention, that control points of cubic Bezier
curves are not counted as points ...

-> maybe useful to mention, that the default calcMode paced 
requires a (numeric) calculation of the distance along a path for
cubic bezier segments. (Even if the calcMode is linear, the
motion along a cubic Bezier curve segment is paced and 
requires therefore the distance along the path fragment or a
related method, because the usual parametrisations of
cubic Bezier curves are not related to a paced or linear motion).   
Received on Tuesday, 14 August 2007 14:12:42 UTC

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