RE: SMIL Animation

Hi Patrick,

I've noticed that the section 3.4.2 has other errors as well.
(I have checked the errata doc)

In the beginning, it defines i = floor((t*n)/d). 
This causes i to be n (i=n), when t = d (because 0 <= t <= d, defined in
section 3.2.1 and the cumulative and frozen animation functions in
section 3.2.5 call f(d) )

However, this will cause discrete animation function 
f(t) = value[i] to access value[n], which doesn't exist.
(because there are n entries in values attribute, so
only value[0]...value[n-1] exist)

The same array access problem exists in linear and paced equations,
as well. For instance, in paced anim, it explicitely says 0<i<= n, 
so i can be n, which is wrong!

D(i) = dist(value[0],value[1]) + dist(value[1],value[2]) +...+
dist(value[i-1],value[i]), for integers i with 0<i<= n.

I haven't checked the spline equation.

regards,
     Kari

On Wed, 2 Jan 2002, Patrick Schmitz wrote:

> Hello Taras -
> 
> Sorry for the long delay in responding - I was busy with some other work and
> took a break over the holidays.
> 
> In the equation you mention, the subscript i refers the current interval
> from the set of n-1 intervals.  As such, t(sub)i is the time associated with
> the beginning of the 'i'th interval.
> 
> As I review the section, I believe I see an erratum in this equation - I
> will take this up with the SMIL WG.
> 
> Thanks - Patrick
> 
> > -----Original Message-----
> > From: Taras Shymbra [mailto:terry@inobject.com]
> > Sent: Tuesday, December 18, 2001 3:16 AM
> > To: cogit@ludicrum.org
> > Subject: SMIL Animation
> >
> >
> > Dear Patrick Schmitz,
> >
> > In the SMIL 2.0 Specification (part 3 -> "The SMIL 2.0 Animation Modules")
> > it is declared:
> >
> > "For linear animation, the duration is divided into n-1 equal periods, and
> > the animation function is a linear interpolation between the
> > values at the
> > associated times:
> >       f(t) = value[i] + (value[i+1]-value[i]) * (t-ti)/d. "
> >
> > Would You please clarify what is the semantics of the "ti" in
> > this animation
> > function equation?
> >
> > Thank You in advance,
> > Sincerely Yours,
> >
> > Taras Shymbra
> >
>

Received on Monday, 18 February 2002 04:37:40 UTC