[Bf-committers] sequence.c

[Kent Mein]

In reply to Shaul Kedem (shaul.kedem at gmail.com):

> Also..
>  Just wanted to add that I went to the cvs and back to the initial version, 
> there too it is += for what looks like no apparent reason,
>  Shaul

Its there for a very good reason.  
I'm not trying to sound like a jerk, hard to explain it through email but
I'll try to explain.  The sudo code may be slightly off but you should get 
the idea.
Its the same thing as image data we have something like this:
unsigned char *pict = (unsigned char *)imbuf->rect;

if we do a pict++;
pict now points to the second element in the rect data structure.
instead of cycling through them all though if we do:
unsigned char *pict = (unsigned char *)imbuf->rect; /* now it points to the start again */
pict+=10;
We jump ahead 10 elements.

If you look at the code below "se" points to the strip->stripdata.
Which is all of the strip information....  But we don't want that we really
want the data from "frame" nr so we need to do a 
se+= nr;
Then we can play with our data and do whatever we need.  (All the other
code here just determines what nr should be and then at the very
end makes sure that in our current stripdata
strip->stripdata[nr]   we set nr to = nr.
or strip->stripdata[nr]->nr = nr;

There is no   ok I want frame 10,9, 22, this bit of code is just
giving the element of the strip at cfra.  So what we do is
translate cfra into an element # of the strip (or frame number for the strip)
stick that in nr and look it up and return it.
and just to be safe we set that element's nr (probably needs it)

Kent

> > > > StripElem *give_stripelem(Sequence *seq, int cfra)
> > > > {
> > > > Strip *strip;
> > > > StripElem *se;
> > > > int nr; 
> > > >
> > > > strip= seq->strip;
> > > > se= strip->stripdata;
> > > >
> > > > *if*(se==0) *return* 0;
> > > > *if*(seq->startdisp >cfra || seq->enddisp <= cfra) *return* 0;
> > > >
> > > > *if*(cfra <= seq->start) nr= 0;
> > > > *else* *if*(cfra >= seq->start+seq->len-1) nr= seq->len-1;
> > > > *else* nr= cfra-seq->start;
> > > >
> > > >
> > > > se+= nr; 
> > > > se->nr= nr;
> > > >
> > > > *return* se;
> > > > }
> > > >

-- 
mein at cs.umn.edu
http://www.cs.umn.edu/~mein