move test caves to base:demo

res/content/base/generators/demo.files/script.lua

@@ -1,3 +1,13 @@
+-- Get entry-point and filename from `entry-point:filename` path 
+-- // TODO: move to stdmin
+function parse_path(path)
+    local index = string.find(path, ':')
+    if index == nil then
+        error("invalid path syntax (':' missing)")
+    end
+    return string.sub(path, 1, index-1), string.sub(path, index+1, -1)
+end
+
 local _, dir = parse_path(__DIR__)
 ores = file.read_combined_list(dir.."/ores.json")
 
@@ -26,6 +36,17 @@ end
 function place_structures(x, z, w, d, seed, hmap, chunk_height)
     local placements = {}
     place_ores(placements, x, z, w, d, seed, hmap, chunk_height)
+
+    if math.random() < 0.1 then -- generate caves
+        local sy = math.random() * (chunk_height / 2)
+        local ey = math.random() * (chunk_height / 2)
+        local sx = x + math.random() * 20 - 10
+        local ex = x + math.random() * 20 - 10
+        local sz = z + math.random() * 20 - 10
+        local ez = z + math.random() * 20 - 10
+        table.insert(placements, 
+            {":line", 0, {sx - 10, sy, sz - 10}, {ex + 10, ey, ez + 10}, 3})
+    end
     return placements
 end