Re: Gnuplot crashing for "hidden3d undefined" ?

[<HBB...@t-...>]

Ethan A Merritt wrote:
> On Saturday 27 October 2007 13:07, Hans-Bernhard Bröker wrote:

>> The problem itself is an internal constraint violation in the hidden3d 
>> algorithm.  Something broke the code designed to ensure that 
>> out-of-range data points don't make it to that point of the algorithm.

> 2005-12-06  Hans-Bernhard Broeker  <br...@ph...>
> 
>         * src/hidden3d.c (COORD_TO_TREECELL, COORD_TO_BITMASK): Avoid
>         overflow by undoing effect of surface_scale before mapping to
>         integers.
>         (store_polygon): Add assert()s to internal macros GET_MIN,
>         GET_MAX, to catch problems not handled by above changes.

The overflows that this was designed to avoid would be those 
wrap-arounds mentioned elsewhere in this thread.

Ultimately, the 'undefined <n>' option to hidden3d may have become 
unviable due to this change.  At level 3 it is already documented as 
"use at your own risk".  The simplest option would be to extend that 
warning to all settings other than the default of 1.0.

> So it's your change.  Do you want to have a look at it?

I'll try to find some time to do that.

> So I there are two separate issues here:
>   
> 1) We changed the default 4.2 configuration to --enable-h3d-quadtree

But only for ./configure builds.  The config/makefile.* and 
config/config.* files weren't all updated.

> 2) The non-quadtree version was subsequently broken by the patch from 1.53 -> 1.54

IIRC, the quadtree variant does its own implicit limit testing 
elsewhere, so it doesn't really need those assert()s.