From a8ba74843439e1ad1157db7621cbd1a5ae10e428 Mon Sep 17 00:00:00 2001
From: planetmaker <planetmaker@openttd.org>
Date: Mon, 6 May 2013 20:48:18 +0000
Subject: [PATCH] (svn r25229) -Feature: [NewGRF] Variable 0x82 for canals and
 rivers (dike map)

---
 src/newgrf_canal.cpp | 24 ++++++++++++++++++++++++
 src/water.h          |  2 ++
 src/water_cmd.cpp    |  2 +-
 3 files changed, 27 insertions(+), 1 deletion(-)

diff --git a/src/newgrf_canal.cpp b/src/newgrf_canal.cpp
index 13b7e15d6e..ef678a0ccc 100644
--- a/src/newgrf_canal.cpp
+++ b/src/newgrf_canal.cpp
@@ -13,6 +13,7 @@
 #include "debug.h"
 #include "newgrf_spritegroup.h"
 #include "newgrf_canal.h"
+#include "water.h"
 #include "water_map.h"
 
 /** Table of canal 'feature' sprite groups */
@@ -66,6 +67,29 @@ struct CanalResolverObject : public ResolverObject {
 		/* Terrain type */
 		case 0x81: return GetTerrainType(this->tile);
 
+		/* Dike map: Connectivity info for river and canal tiles
+		 *
+		 * Assignment of bits to directions defined in agreement with
+		 * http://projects.tt-forums.net/projects/ttdpatch/repository/revisions/2367/entry/trunk/patches/water.asm#L879
+		 *         7
+		 *      3     0
+		 *   6     *     4
+		 *      2     1
+		 *         5
+		 */
+		case 0x82: {
+			uint32 connectivity =
+				  (!IsWateredTile(TILE_ADDXY(tile, -1,  0), DIR_SW) << 0)  // NE
+				+ (!IsWateredTile(TILE_ADDXY(tile,  0,  1), DIR_NW) << 1)  // SE
+				+ (!IsWateredTile(TILE_ADDXY(tile,  1,  0), DIR_NE) << 2)  // SW
+				+ (!IsWateredTile(TILE_ADDXY(tile,  0, -1), DIR_SE) << 3)  // NW
+				+ (!IsWateredTile(TILE_ADDXY(tile, -1,  1), DIR_W)  << 4)  // E
+				+ (!IsWateredTile(TILE_ADDXY(tile,  1,  1), DIR_N)  << 5)  // S
+				+ (!IsWateredTile(TILE_ADDXY(tile,  1, -1), DIR_E)  << 6)  // W
+				+ (!IsWateredTile(TILE_ADDXY(tile, -1, -1), DIR_S)  << 7); // N
+			return connectivity;
+		}
+
 		/* Random data for river or canal tiles, otherwise zero */
 		case 0x83: return IsTileType(this->tile, MP_WATER) ? GetWaterTileRandomBits(this->tile) : 0;
 	}
diff --git a/src/water.h b/src/water.h
index 1e8152f73a..cb7237fc7c 100644
--- a/src/water.h
+++ b/src/water.h
@@ -41,6 +41,8 @@ void MakeWaterKeepingClass(TileIndex tile, Owner o);
 
 bool RiverModifyDesertZone(TileIndex tile, void *data);
 
+bool IsWateredTile(TileIndex tile, Direction from);
+
 /**
  * Calculates the maintenance cost of a number of canal tiles.
  * @param num Number of canal tiles.
diff --git a/src/water_cmd.cpp b/src/water_cmd.cpp
index ccda7fb063..b99741cfe9 100644
--- a/src/water_cmd.cpp
+++ b/src/water_cmd.cpp
@@ -548,7 +548,7 @@ static CommandCost ClearTile_Water(TileIndex tile, DoCommandFlag flags)
  * @return true iff the tile is water in the view of 'from'.
  *
  */
-static bool IsWateredTile(TileIndex tile, Direction from)
+bool IsWateredTile(TileIndex tile, Direction from)
 {
 	switch (GetTileType(tile)) {
 		case MP_WATER: