add a "digtron_protected" node group for modders to use if they want to prevent digtrons from digging their nodes

2 files changed, 2 insertions, 1 deletions

diff --git a/README.txt b/README.txt
index c5cac53..e2ba95e 100644
--- a/README.txt
+++ b/README.txt
@@ -13,6 +13,7 @@ The basic nodes that can be assembled into a functioning digging machine are:
 
 A digging machine's components must be connected to the control node via a path leading through the faces of the nodes - diagonal connections across edges and corners don't count.
 
+Note for modders: if you wish to make a node impenetrable to Digtron's digging, add it to the "digtron_protected" group.
 
 Crafting recipes
 ================
diff --git a/util.lua b/util.lua
index 354edcd..e32c16b 100644
--- a/util.lua
+++ b/util.lua
@@ -41,7 +41,7 @@ digtron.mark_diggable = function(pos, nodes_dug)
 	local target = minetest.get_node(pos)
 	
 	-- prevent digtrons from being marked for digging.
-	if minetest.get_item_group(target.name, "digtron") ~= 0 then
+	if minetest.get_item_group(target.name, "digtron") ~= 0 or minetest.get_item_group(target.name, "digtron_protected") ~= 0 then
 		return 0, {}
 	end