[Freeciv-Dev] Re: Map coordinate cleanups.

[Jason Dorje Short <jshort@xxxxxxxxxxxxx>]

Trent Piepho wrote:
> 
> On Thu, 16 Aug 2001, Gaute B Strokkenes wrote:
> > Attached is patch that fixes several instances where Freeciv
> > inadvertently creates unnormalised map coordinates or makes use of
> > unreal map coordinates.  It also changes the is_real_tile() function
> > to a macro IS_REAL_TILE(), and adds macros IS_NORM_TILE() and
> > IS_PROP_TILE(), and some other coordinate related things.
> 
> If you ever want to support topologies other than a cylinder, you probably
> don't want to make these a macro.  IS_NORM_TILE would become quite a mess of
> ?: operators just to support the three most simple map types of plane,
> cylinder, and sphere, not even considering the crazy shit like Mobius strips
> some people were talking about.
> 
> Also, most of the places these functions are used is inside debugging assert
> calls.  There is no point in making those faster since they are just for
> debugging.  So there is no good reason to make it a macro in the first place.

> I also don't think making normal no longer a subset of real makes much sense.

I agree entirely with Trent on this one:

1.  The only reason to make these functions macros is speed.  Speed is a
small concern compared to the possibility of having multiple topologies.

2.  I think we have some confusion over the meaning of "normal".  I
don't see how the coordinates (2, -1) could possibly be normal.  I don't
understand the difference you claim between "normal" and "proper"
coordinates.  If you're saying they're "normal" because they can't be
wrapped to anything, then...it's a nomenclature problem.  We should
agree on a name (normal or proper, whatever), and use that.  I don't see
how the macro IS_NORM_TILE you describe would ever be useful.

Note that my definition of is_normal_tile corresponds very closely to
normalize_map_pos.  Using normal to mean something else would be _very_
confusing IMO.

jason