Re-write pistons from scratch, propably fixes a lot of bugs and doesn't cause too many new ones.

mesecons_mvps/init.lua

@@ -2,42 +2,99 @@
 
 mesecon.mvps_stoppers={}
 
-function mesecon:is_mvps_stopper(nodename)
-	local i=1
-	repeat
-		i=i+1
-		if mesecon.mvps_stoppers[i]==nodename then return true end
-	until mesecon.mvps_stoppers[i]==nil
-	return false
+function mesecon:is_mvps_stopper(node, pushdir, stack, stackid)
+	local get_stopper = mesecon.mvps_stoppers[node.name]
+	if type (get_stopper) == "function" then
+		get_stopper = get_stopper(node, pushdir, stack, stackid)
+	end
+	return get_stopper
 end
 
-function mesecon:register_mvps_stopper(nodename)
-	local i=1
-	repeat
-		i=i+1
-		if mesecon.mvps_stoppers[i]==nil then break end
-	until false
-	mesecon.mvps_stoppers[i]=nodename
+function mesecon:register_mvps_stopper(nodename, get_stopper)
+	if get_stopper == nil then
+			get_stopper = true
+	end
+	mesecon.mvps_stoppers[nodename] = get_stopper
 end
 
-function mesecon:mvps_push(pos, direction) -- pos: pos of mvps; direction: direction of push
-		pos.x=pos.x+direction.x
-		pos.y=pos.y+direction.y
-		pos.z=pos.z+direction.z
+function mesecon:mvps_process_stack(stack)
+	-- update mesecons for placed nodes ( has to be done after all nodes have been added )
+	for _, n in ipairs(stack) do
+		mesecon.on_placenode(n.pos, n.node)
+		mesecon:update_autoconnect(n.pos)
+	end
+end
 
-		local lpos = {x=pos.x, y=pos.y, z=pos.z}
-		local lnode = minetest.env:get_node(lpos)
-		local newnode
-		minetest.env:remove_node(lpos)
-		while not(lnode.name == "ignore" or lnode.name == "air" or not(minetest.registered_nodes[lnode.name].liquidtype == "none")) do
-			lpos.x=lpos.x+direction.x
-			lpos.y=lpos.y+direction.y
-			lpos.z=lpos.z+direction.z
-			newnode = lnode
-			lnode = minetest.env:get_node(lpos)
-			minetest.env:add_node(lpos, newnode)
-			nodeupdate(lpos)
+function mesecon:mvps_push(pos, dir, maximum) -- pos: pos of mvps; dir: direction of push; maximum: maximum nodes to be pushed
+	np = {x = pos.x, y = pos.y, z = pos.z}
+
+	-- determine the number of nodes to be pushed
+	local nodes = {}
+	while true do
+		nn = minetest.env:get_node_or_nil(np)
+		if not nn or #nodes > maximum then
+			-- don't push at all, something is in the way (unloaded map or too many nodes)
+			return
 		end
+
+		if nn.name == "air"
+		or minetest.registered_nodes[nn.name].liquidtype ~= "none" then --is liquid
+			break
+		end
+
+		table.insert (nodes, {node = nn, pos = np})
+
+		np = mesecon:addPosRule(np, dir)
+	end
+
+	-- determine if one of the nodes blocks the push
+	for id, n in ipairs(nodes) do
+		if mesecon:is_mvps_stopper(n.node, dir, nodes, id) then
+			return
+		end
+	end
+
+	-- remove all nodes
+	for _, n in ipairs(nodes) do
+		minetest.env:remove_node(n.pos)
+		nodeupdate(n.pos)
+	end
+
+	-- update mesecons for removed nodes ( has to be done after all nodes have been removed )
+	for _, n in ipairs(nodes) do
+		mesecon.on_dignode(n.pos, n.node)
+		mesecon:update_autoconnect(n.pos)
+	end
+
+	-- add nodes
+	for _, n in ipairs(nodes) do
+		np = mesecon:addPosRule(n.pos, dir)
+		minetest.env:add_node(np, n.node)
+		nodeupdate(np)
+	end
+
+	for i in ipairs(nodes) do
+		nodes[i].pos = mesecon:addPosRule(nodes[i].pos, dir)
+	end
+
+	return true, nodes
+end
+
+function mesecon:mvps_pull_single(pos, dir) -- pos: pos of mvps; direction: direction of pull (matches push direction for sticky pistons)
+	np = mesecon:addPosRule(pos, dir)
+	nn = minetest.env:get_node(np)
+
+	if minetest.registered_nodes[nn.name].liquidtype == "none"
+	and not mesecon:is_mvps_stopper(nn, {x = -dir.x, y = -dir.y, z = -dir.z}, {{pos = np, node = nn}}, 1) then
+		minetest.env:remove_node(np)
+		minetest.env:add_node(pos, nn)
+
+		nodeupdate(np)
+		nodeupdate(pos)
+		mesecon.on_dignode(np, nn)
+		mesecon:update_autoconnect(np)
+	end
+	return {{pos = np, node = nn}}
 end
 
 function mesecon:mvps_pull_all(pos, direction) -- pos: pos of mvps; direction: direction of pull