[GRASS5] [bug #4246] (grass) NVIZ: segfault in kanimation panel

[Hamish]

> > I am using Debian with TclTk 8.4, which is a new thing. See:
> >   http://article.gmane.org/gmane.comp.gis.grass.devel/11177
> >   http://grass.itc.it/pipermail/grass-commit/2006-March/021104.html
> > 
> > Maybe a similar issue?
..
> > > I do get the compiler warning for all of the Tcl_SplitList in src.
> > > According to TCL recent documentation arg 4 in Tcl_SplitList
> > > should actually be "const char **". If I change 
> > > char **listels;
> > > in anim_support.c (line ~933)
> > > to const char **listels;
> > > I do not get the compiler warning.
> > 
> > If I add "const", the warning goes away for me too. But it still
> > segfaults on Load anim file.
> > 
> > I also notice these warnings:
> > 
> > <command line>:5:1: warning: "__STDC__" redefined
> > In file included from anim_support.c:11:
> > interface.h:363: warning: `struct Map_info' declared inside
> > parameter list interface.h:363: warning: its scope is only this
> > definition or declaration, which is probably not what you want


> > > Also, according to the Tcl_SplitList documentation, the **listels
> > > argument should be freed. They recommend using 
> > > Tcl_Free((char *) argv);
> > > 
> > > I am not sure why the free call would be creating a problem. 
> > 
> > see above links ??
> 
> Taking a look at some of the other Tcl_SplitList calls (for example in
> draw.c) the char is freed with G_free ((char *) ...). I would expect
> these to also segfault if it was a problem with G-free. Try simply
> changing 
> G_free (listels);
> to 
> G_free ((char *) listels);

Nope, still segfaults.



> > Also I added an #ifdef to the MPEG code to make it easy to switch to
> > using the XVID codec. (compile with gcc -D"USE_XVID") This should
> > really be an enviro var or GIS var setting, but for now it's a quick
> > proof of  concept hack.
> 
> Instead of a compile flag could we try something like ...
> codec = avcodec_find_encoder(CODEC_ID_XVID);
> if (!codec)
> {
> 	codec = avcodec_find_encoder(CODEC_ID_MPEG1VIDEO);
> 	if (!codec) {
> 		fprintf(stderr, "codec not found\n");
> 		return(-1);
> 	}
> }
> This way it tries to load the better quality codec, and if it fails it
> will load the old standard mpeg1. I have not tested it to see if it
> works. 

Maybe someone wants something more than XVID or MPEG-1?
 (shrug- anybody?)

XVID requires the canvas to be some multiple of 16x16, and fails to
load (without telling why) or produces artifacts in the output if not. 
So as a default it may be tricky for newcomers.. But most/all other
encoders have the same problem. (including MPEG-1??)


> > Q: If I make a track with d.nviz the camera looks straight down, not
> > forwards along the track. Is this normal/expected?
> 
> If the camera is looking down then you need to increase the dist
> parameter. The combination of the ht and dist parameters are what
> determine the camera look angle. 

Oh, ok. I was keeping dist= small as I was getting out-of-region
messages and skipped points if I went within that distance to the edge
of the region. Any thoughts on extending the module to work with a
vector line? Maybe needs a cat= option tp pick specific line and a -r
reverse flag to follow it the other direction. I'm thinking flying above
a road or weaking the flight path in v.digit.


Hamish