extend stdmin.lua & add module base:generation/ores

res/content/base/modules/generation/ores.lua

@@ -0,0 +1,29 @@
+local ores = {}
+
+function ores.load(directory)
+    ores.ores = file.read_combined_list(directory.."/ores.json")
+end
+
+function ores.place(placements, x, z, w, d, seed, hmap, chunk_height)
+    local BLOCKS_PER_CHUNK = w * d * chunk_height
+    for _, ore in ipairs(ores.ores) do
+        local count = BLOCKS_PER_CHUNK / ore.rarity
+
+        -- average count is less than 1
+        local addchance = math.fmod(count, 1.0)
+        if math.random() < addchance then
+            count = count + 1
+        end
+
+        for i=1,count do
+            local sx = math.random() * w
+            local sz = math.random() * d
+            local sy = math.random() * (chunk_height * 0.5)
+            if sy < hmap:at(sx, sz) * chunk_height - 6 then
+                table.insert(placements, {ore.struct, {sx, sy, sz}, math.random()*4, -1})
+            end
+        end
+    end
+end
+
+return ores