add api for getting the walkability group of a tile

docs/changelog.txt

@@ -67,9 +67,11 @@ Template for new versions:
 
 ## API
 - ``Gui::revealInDwarfmodeMap``: gained ``highlight`` parameter to control setting the tile highlight on the zoom target
+- ``Maps::getWalkableGroup``: get the walkability group of a tile
 
 ## Lua
 - ``dfhack.gui.revealInDwarfmodeMap``: gained ``highlight`` parameter to control setting the tile highlight on the zoom target
+- ``dfhack.maps.getWalkableGroup``: get the walkability group of a tile
 
 ## Removed
 

docs/dev/Lua API.rst

@@ -1912,10 +1912,11 @@ Maps module
 
   Returns the plant struct that owns the tile at the specified position.
 
-* ``dfhack.maps.canWalkBetween(pos1, pos2)``
+* ``dfhack.maps.getWalkableGroup(pos)``
 
-  Checks if a dwarf may be able to walk between the two tiles,
-  using a pathfinding cache maintained by the game.
+  Returns the walkability group for the given tile position. A return value of
+  ``0`` indicates that the tile is not walkable. The data comes from a
+  pathfinding cache maintained by DF.
 
   .. note::
     This cache is only updated when the game is unpaused, and thus
@@ -1924,6 +1925,10 @@ Maps module
     take into account anything that depends on the actual units, like
     burrows, or the presence of invaders.
 
+* ``dfhack.maps.canWalkBetween(pos1, pos2)``
+
+  Checks if both positions are walkable and also share a walkability group.
+
 * ``dfhack.maps.hasTileAssignment(tilemask)``
 
   Checks if the tile_bitmask object is not *nil* and contains any set bits; returns *true* or *false*.

library/LuaApi.cpp

@@ -2239,6 +2239,7 @@ static const LuaWrapper::FunctionReg dfhack_maps_module[] = {
     WRAPM(Maps, enableBlockUpdates),
     WRAPM(Maps, getGlobalInitFeature),
     WRAPM(Maps, getLocalInitFeature),
+    WRAPM(Maps, getWalkableGroup),
     WRAPM(Maps, canWalkBetween),
     WRAPM(Maps, spawnFlow),
     WRAPN(hasTileAssignment, hasTileAssignment),

library/include/modules/Maps.h

@@ -339,6 +339,7 @@ extern DFHACK_EXPORT bool SortBlockEvents(df::map_block *block,
 extern DFHACK_EXPORT bool RemoveBlockEvent(int32_t x, int32_t y, int32_t z, df::block_square_event * which );
 extern DFHACK_EXPORT bool RemoveBlockEvent(uint32_t x, uint32_t y, uint32_t z, df::block_square_event * which ); // todo: deprecate me
 
+DFHACK_EXPORT uint16_t getWalkableGroup(df::coord pos);
 DFHACK_EXPORT bool canWalkBetween(df::coord pos1, df::coord pos2);
 DFHACK_EXPORT bool canStepBetween(df::coord pos1, df::coord pos2);
 

library/modules/Maps.cpp

@@ -622,16 +622,15 @@ bool Maps::ReadGeology(vector<vector<int16_t> > *layer_mats, vector<df::coord2d>
     return true;
 }
 
+uint16_t Maps::getWalkableGroup(df::coord pos) {
+    auto block = getTileBlock(pos);
+    return block ? index_tile(block->walkable, pos) : 0;
+}
+
 bool Maps::canWalkBetween(df::coord pos1, df::coord pos2)
 {
-    auto block1 = getTileBlock(pos1);
-    auto block2 = getTileBlock(pos2);
-
-    if (!block1 || !block2)
-        return false;
-
-    auto tile1 = index_tile(block1->walkable, pos1);
-    auto tile2 = index_tile(block2->walkable, pos2);
+    auto tile1 = getWalkableGroup(pos1);
+    auto tile2 = getWalkableGroup(pos2);
 
     return tile1 && tile1 == tile2;
 }

plugins/buildingplan/buildingplan_cycle.cpp

@@ -12,7 +12,6 @@
 #include "df/item.h"
 #include "df/item_slabst.h"
 #include "df/job.h"
-#include "df/map_block.h"
 #include "df/world.h"
 
 #include <unordered_map>
@@ -48,14 +47,10 @@ struct BadFlags {
 // up or down (e.g. for stairs). For now, just return if the item is on a walkable tile.
 static bool isAccessible(color_ostream& out, df::item* item) {
     df::coord item_pos = Items::getPosition(item);
-    df::map_block* block = Maps::getTileBlock(item_pos);
-    bool is_walkable = false;
-    if (block) {
-        uint16_t walkability_group = index_tile(block->walkable, item_pos);
-        is_walkable = walkability_group != 0;
-        TRACE(cycle, out).print("item %d in walkability_group %u at (%d,%d,%d) is %saccessible from job site\n",
-            item->id, walkability_group, item_pos.x, item_pos.y, item_pos.z, is_walkable ? "(probably) " : "not ");
-    }
+    uint16_t walkability_group = Maps::getWalkableGroup(item_pos);
+    bool is_walkable = walkability_group != 0;
+    TRACE(cycle, out).print("item %d in walkability_group %u at (%d,%d,%d) is %saccessible from job site\n",
+        item->id, walkability_group, item_pos.x, item_pos.y, item_pos.z, is_walkable ? "(probably) " : "not ");
     return is_walkable;
 }