[Freeciv-Dev] Re: (PR#3936) introducing native coordinates

[Ross Wetmore <rwetmore@xxxxxxxxxxxx>]

Raimar Falke wrote:
> On Wed, Apr 23, 2003 at 05:50:43PM -0500, Jason Dorje Short wrote:
>
> > Raimar Falke wrote:
[...]
> > Using "map coordinates" rather than "native coordinates" as standard is 
> > fastest, since the vast, vast, vast majority of operations are done on 
> > map coordinates.
> I disagree here. Every tile access needs the compact form. The same is
> true for normalize_map_pos and is_normal_map_pos. But without testing
> we won't find out.
Wrong on aeveral counts.

Tile accesses are done in indexed coordinates - memory is linear.

All game logic is handled in standard/internal coordinates including
things like the local iterators. The Freeciv foundations are based on
a standard map grid and changing this is a lot of work to make things
less efficient and much more complex in a number of cases.

> > > - which iso variants do we support (IMHO both)
> > Hmm?  The "variants" you talk about in the file are just a different 
> > numbering system; there's nothing fundamentally different between them.
Raimar is starting from scratch with his version and may take some time
until he comes up to speed on what is relevant and what is not.

Meanwhile we should try to avoid too much wheel reinvention and try to
keep the discussion on reviewing things relevant to the proposed patch,
rather than always getting sidetracked too far into dead ends.

[...]
> > > - in which form is wrapping defined? Do we support multiple wrapping
> > > forms (iso view form and non-iso view form)?
> > I don't know what this means.  Wrapping is defined for both iso and 
> > non-iso maps, and is identical in both when done in "native coordinates".
> Ok so the wrapping operations are defnied in the compact
> form. Question: is wrapping defined in compact form the same as
> wrapping defined in iso-view form? IMHO yes but I'm not sure.
The wrapping concept is the same no matter which coordinate you choose
to use for the implementation. Some coordinate systems are more
efficient at doing this, i.e. aligned with the wrap axes.

> > > - how can mapview code done in an easier way (IMHO with an
> > > intermediate form)
> > Again you are lumping a whole collection of unrelated operations into 
> > one term.
> This is a bit terse.
>
> I'm trying to split unnormalize_map_pos into two operations. First the
> wrapping and than the rotating and scaling to pixels. What is your
> opinion?
Unnormalize_map_pos only does (un)wrapping.

Rotations and scaling are done in other code.

I think you need to take another look ...

>         Raimar
Cheers,
RossW
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