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

[Raimar Falke <rf13@xxxxxxxxxxxxxxxxx>]

On Fri, Apr 11, 2003 at 04:11:14AM -0500, Jason Dorje Short wrote:
> Raimar Falke wrote:
> >On Thu, Apr 10, 2003 at 11:04:02PM +0200, Raimar Falke wrote:
> >
> >Some more findings: 
> >
> >It is possible to define the rotated form on the compact form (like I
> >did in the past) but it is also possible to use the view form. This
> >has the advantage that you get a natural shaped neighborhood for both
> >iso-view and non-iso-view. So you take the iso-view (grid_iso.png) and
> >rotate it to get the rotated form (grid_iso_rot.png). This makes it
> >impossible to define the neighborhood on the compact form and so
> >square_map_iterate need to be changed.
> 
> You still need to define these terms if you expect anyone to understand 
> this paragraph.

It is about grid_iso_rot.png vs grid_rot.png. It is now clear to me
that it should be grid_iso_rot.png.

> >There are two possible iso-view forms for a given compact map
> >(9x5). See grid_iso.png and grid_iso2.png. None of these two is
> >naturally to prefer. These are the neighborhood relations for these
> >two possible iso-views:
> >
> >iso: c1, c5, b3, d3, b2, c2, b4, c4
> >iso2: c2, c4, a3, e3, b2, d2, b3, d3
> >
> >They differ. So which one do we choose? And why? Or do we support
> >both?
> 
> It looks to me like you have discovered that iso-native coordinates can 
> be obtained by compressing iso-natural coordinates in either the X or 
> the Y direction.

Yes you can it also describe this way.

> Ross chose the X direction for this, claiming that it leads to
> better cache performance with map.tiles.  I have found that there
> are some advantages to using the Y direction, but only because it
> makes some of the hacks used elsewhere in the code work out better
> (e.g., the map overview).

I have heard about this the first time. It also isn't mentioned in
your last native coordinates patch.

> This makes some sense.  But please try to distinguish which map you are 
> representing, and which coordinate system you are using.  For instance is a

    THERE IS ONLY ONE COORDINATE SYSTEM. EACH TILE HAS EXACTLY ONE
    PAIR (x,y).

This is different to your idea but I think it makes it easier to
understand. At least for me.

        Raimar

-- 
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