Re: [Rails-devel] Tile orientation display

[John A. T. <ja...@ja...>]

On Sat, Jul 16, 2011 at 2:02 AM, Stefan Frey <ste...@we...> wrote:

> imho the canonical orientation intends to solve same issue, however it uses
> a
> different algorithm, thus there will be different orientations.
>
> And it seems that it does not orientate tile 25 (switch with two broad
> curves)
> uniquely: There are three configurations that have identical position of
> the
> exits: The switch can either be in position D, F or B, however exits are
> still
> always B, D and F.
> This problem arises for all tiles with symmetrical exits, but asymmetrical
> tracks.
> But maybe I have misunderstood something there (likely given the expertise
> of
> the discussants).
>

The point of a canonical orientation is that there is only one (if there is
more than one, such as for tile #9, then they are indistinguishable for all
purposes).  I'm not sure which canonical rules you are referring to, but in
the one I proposed (and use) there is exactly one possible base orientation
for #25, which is branches from D to B and F.  You have other cases that
have to be dealt with in the canonical rules, such as when there is internal
connectivity, such as between multiple city clusters and external exits, but
it is easy enough to extend the canonicalization rules to accomodate those.

-- 
John A. Tamplin