Re: animateMotion keyTimes question

Hello,

the concept of keyPoints of SVG animateMotion goes beyond the simple concept 
of SMIL values animations (including alternative writings with from-to, 
from-by or by animation). The number of keyPoints can be different from the 
number of values or vertices in a path, else the concept of keyPoints would 
be almost useless. With an arbitrary number of keyPoints in arbitrary order 
one can move several times forward and backward on the path without blowing
up the source code with redundant path data, values etc. And obviously an 
author has access to arbitrary points within a motion path without the need 
to calculate them explicitly just for this purpose.

Therefore if keyPoints is noted, this implicates the number of list items for
keyTimes or keySplines and some new kind of effective motion trajectory, 
that can have more relevant items than a values list.

It is noted: "If a list of ‘keyPoints’ is specified, there must be exactly as 
many values in the ‘keyPoints’ list as in the ‘keyTimes’ list."
This means, if you note four values for keyPoints, there have to be four
for keyTimes and vice versa. The number of items in the values list or
the number of path vertices is not really relevant here.
However, because this new concept of keyPoints was only added in SVG
to the simpler SMIL concept, it can be confusing, that SMIL only explains
the concept of values lists. SVG could have been clearer here in the
explanation of ‘keyPoints’.

Of course one could add a hint to the description of keyPoints, that it 
results in some new kind of structure of the motion, not directly related to 
the number of list items or path vertices.


Olaf

Received on Wednesday, 13 August 2014 08:21:00 UTC