Add group-based tool filtering for node drops (#10141)

Supports both AND and OR requirements, e.g.

 * "a tool that's in any of these groups"
 * "a tool that's in all of these groups"

Author: Treer

builtin/game/item.lua

@@ -175,6 +175,18 @@ function core.strip_param2_color(param2, paramtype2)
 	return param2
 end
 
+local function has_all_groups(tbl, required_groups)
+	if type(required_groups) == "string" then
+		return (tbl[required_groups] or 0) ~= 0
+	end
+	for _, group in ipairs(required_groups) do
+		if (tbl[group] or 0) == 0 then
+			return false
+		end
+	end
+	return true
+end
+
 function core.get_node_drops(node, toolname)
 	-- Compatibility, if node is string
 	local nodename = node
@@ -214,7 +226,7 @@ function core.get_node_drops(node, toolname)
 		if item.rarity ~= nil then
 			good_rarity = item.rarity < 1 or math.random(item.rarity) == 1
 		end
-		if item.tools ~= nil then
+		if item.tools ~= nil or item.tool_groups ~= nil then
 			good_tool = false
 		end
 		if item.tools ~= nil and toolname then
@@ -229,6 +241,27 @@ function core.get_node_drops(node, toolname)
 				end
 			end
 		end
+		if item.tool_groups ~= nil and toolname then
+			local tooldef = core.registered_items[toolname]
+			if tooldef ~= nil and type(tooldef.groups) == "table" then
+				if type(item.tool_groups) == "string" then
+					-- tool_groups can be a string which specifies the required group
+					good_tool = core.get_item_group(toolname, item.tool_groups) ~= 0
+				else
+					-- tool_groups can be a list of sufficient requirements.
+					-- i.e. if any item in the list can be satisfied then the tool is good
+					assert(type(item.tool_groups) == "table")
+					for _, required_groups in ipairs(item.tool_groups) do
+						-- required_groups can be either a string (a single group),
+						-- or an array of strings where all must be in tooldef.groups
+						good_tool = has_all_groups(tooldef.groups, required_groups)
+						if good_tool then
+							break
+						end
+					end
+				end
+			end
+		end
 		if good_rarity and good_tool then
 			got_count = got_count + 1
 			for _, add_item in ipairs(item.items) do

doc/lua_api.txt

@@ -7798,14 +7798,24 @@ Used by `minetest.register_node`.
                     inherit_color = true,
                 },
                 {
-                    -- Only drop if using a item whose name contains
+                    -- Only drop if using an item whose name contains
                     -- "default:shovel_" (this item filtering by string matching
-                    -- is deprecated).
+                    -- is deprecated, use tool_groups instead).
                     tools = {"~default:shovel_"},
                     rarity = 2,
                     -- The item list dropped.
                     items = {"default:sand", "default:desert_sand"},
                 },
+                {
+                    -- Only drop if using an item in the "magicwand" group, or 
+                    -- an item that is in both the "pickaxe" and the "lucky"
+                    -- groups.
+                    tool_groups = {
+                        "magicwand",
+                        {"pickaxe", "lucky"}
+                    },
+                    items = {"default:coal_lump"},
+                },
             },
         },