[Rails-devel] Special tile laying

[Erik V. <eri...@xs...>]

I have committed the first bunch of code to fix problems with laying tiles
using private special properties.
There problems have been reported by John David Galt.

The bugs so far fixed relate to offering, and in some cases even accepting
invalid tile lays by using special properties, such as:
- replacing a yellow tile by another one, e.g. 18AL Lumber Terminal,
- upgrading a yellow tile to a green one, e.g. 1830 F16 (D&H) or B20 (D&H).
The three cases mentioned above now work correctly. I still have to test
other cases in 1835 and 1889.

So far only the game engine has been affected.  The changes include:

1) The already existing but unused option to restrict special tile lays to a
certain colour is now used and enforced.  This applies to 1830 in hex B20
(C&StL).

2) Laying tiles of which the colour is specified explicitly (C&StL) or
implicitly by prescribing  a specific tile (D&H, Lumber Terminal) are now
checked against:
  2a. The colours allowed in the current phase. This has no effect in the
above cases, but it will have effect for the green special upgrade in 1846
(Lake Shore Line).
  2b. The colour of tile(s) already present in any explicitly specified
hexes. See the rules under 3). Blocked hexes are no longer offered (except
in the static help text, unfortunately).  If no hex(es) remain, the special
tile lay will not be offered at all.

3) Any tile to be laid must be either:
  3a. A regular upgrade (blank to yellow, yellow to green etc.), following
normal upgrade rules, or
  3b. An explicitly specified "irregular" upgrade of the old to the new tile
(in TileSet.xml).  I don't know any cases yet where this applies for special
tile lays, but 1856 has regular yellow-to-yellow upgrades, so I think we
must include this case.

4) I have removed the additional inclusion of such special tile lays as
options in the "Special" menu. This was accomplished by a different
mechanism and would not follow the above new rules.
I'm not entirely sure why this menu option had been included, and if it is
really needed.  I'll check my old emails later, but I can think now of two
reasons:
- special tiles lays exist that are permitted outside the normal tile laying
step,
- increasing user-friendliness by adding an alternative procedure, with the
usual "special action" highlight.
In any case, if this feature must be retained, it will have to be provided
by the UI rather than by the game engine, as it was previously.

Erik.