refactor & add structures.json

res/generators/default.lua

@@ -53,6 +53,11 @@ biomes = {
             {block="base:stone", height=-1},
             {block="base:bazalt", height=1},
         },
+        structures = {
+            "tree0",
+            "tree1",
+            "tree2"
+        }
     }
 }
 
@@ -60,7 +65,7 @@ function load_structures()
     local structures = {}
     local names = {"tree0", "tree1", "tree2", "tower"}
     for i, name in ipairs(names) do
-        local filename = "core:default.files/"..name
+        local filename = "core:default/"..name
         debug.log("loading structure "..filename)
         table.insert(structures, generation.load_structure(filename))
     end

res/generators/default/structures.json

@@ -0,0 +1,6 @@
+{
+    "tree0": {},
+    "tree1": {},
+    "tree2": {},
+    "tower": {}
+}