You can only switch places if the destination tile of both creatures is passable for them

git-svn-id: http://svn.net-core.org/repos/t-engine4@4625 51575b47-30f0-44d4-a5cc-537603b46e54

game/engines/default/engine/Map.lua

@@ -581,7 +581,7 @@ function _M:checkAllEntities(x, y, what, ...)
 	end
 end
 
---- Check all entities of the grid for a property, discarding the results
+--- Check all entities of the grid for a property
 -- This will iterate over all entities without stopping.
 -- No guaranty is given about the iteration order
 -- @param x position
@@ -609,6 +609,34 @@ function _M:checkAllEntitiesNoStop(x, y, what, ...)
 	return ret
 end
 
+--- Check all entities of the grid for a property
+-- This will iterate over all entities without stopping.
+-- No guaranty is given about the iteration order
+-- @param x position
+-- @param y position
+-- @param what property to check
+-- @return a table containing all return values, indexed by a list of {layer, entity}
+function _M:checkAllEntitiesLayersNoStop(x, y, what, ...)
+	if not x or not y or x < 0 or x >= self.w or y < 0 or y >= self.h then return {} end
+	local ret = {}
+	local tile = self.map[x + y * self.w]
+	if tile then
+		-- Collect the keys so we can modify the table while iterating
+		local keys = {}
+		for k, _ in pairs(tile) do
+			table.insert(keys, k)
+		end
+		-- Now iterate over the stored keys, checking if the entry exists
+		for i = 1, #keys do
+			local e = tile[keys[i]]
+			if e then
+				ret[{keys[i],e}] = e:check(what, x, y, ...)
+			end
+		end
+	end
+	return ret
+end
+
 --- Check all entities of the grid for a property, counting the results
 -- This will iterate over all entities without stopping.
 -- No guaranty is given about the iteration order

game/modules/tome/class/interface/Combat.lua

@@ -48,6 +48,12 @@ function _M:bumpInto(target, x, y)
 		elseif self.move_others and not target.cant_be_moved then
 			if target.move_others and self ~= game.player then return end
 
+			-- Check we can both walk in the tile we will end up in
+			local blocks = game.level.map:checkAllEntitiesLayersNoStop(target.x, target.y, "block_move", self)
+			for kind, v in pairs(blocks) do if kind[1] ~= Map.ACTOR and v then return end end
+			blocks = game.level.map:checkAllEntitiesLayersNoStop(self.x, self.y, "block_move", target)
+			for kind, v in pairs(blocks) do if kind[1] ~= Map.ACTOR and v then return end end
+
 			-- Displace
 			local tx, ty, sx, sy = target.x, target.y, self.x, self.y
 			target.x = nil target.y = nil