From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>

Date: Sun, 12 Aug 2007 13:01:42 +0200

To: www-smil@w3.org

Message-Id: <200708121301.42551.Dr.O.Hoffmann@gmx.de>

Date: Sun, 12 Aug 2007 13:01:42 +0200

To: www-smil@w3.org

Message-Id: <200708121301.42551.Dr.O.Hoffmann@gmx.de>

Hello SMIL working group, some comments on chapter 12: 12.3.1 typo: '... as well as any time maniuplations defined ...' -> '... as well as any time manipulations defined ...' ------------- 12.3.2 'It will produce a simple pendulum swing on the target (assume that the target is a pendulum shape with the transform origin at the top): <animateTransform type="rotate" from="20" to="-20" dur="1s" repeatCount="indefinite" accelerate=".5" decelerate=".5" autoReverse="true" ... /> The pendulum swings through an arc in one second, and then back again in a second. .... This produces a realistic looking animation of real-world pendulum motion.' -> Note that the motion of a (rotating, mathematical) pendulum is an anharmonic oscillation. It is technically not easy to build a pendulum with such a motion, therefore real-world pendulums behave different. -> The motion related to these attributes is that of a constant force (free fall close to the earth surface) as far as I understand this. With this example it should be possible to produce a quadratic spline approximation for a harmonic oscillation, because it includes autoReverse="true", however I did not check, if the given example really is the correct quadratic spline approximation for a sine related to a harmomic oscillation and it is not the motion of a pendulum, especially not for large amplitudes. -> For (an)harmonic oscillations the autoReverse is still very useful, but the approximation of the motion requires itself a values-animation with calcMode spline and maybe keyTimes. Additionally the values list needs to be calculated symmetrically around '0' to make use of the autoReverse. ------------- Example: "<par speed=2.0> <animate begin="2s" dur="9s" speed="0.75" .../> </par>" -> speed="2.0" ? ------------- 12.3.3 wording? 'r(t) is the speed modification due to acceleration and deceleration, at any time t within the simple duration.' -> as far as I understand this, r(t) is the run rate itself at any time t, not its modification, this would be dr/dt and would be called acceleration. better: -> 'r(t) is the run rate, time dependent due to acceleration and deceleration, at any time t within the simple duration.'Received on Sunday, 12 August 2007 11:15:54 UTC

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