Only serialize node id mappings for nodes that are in block

diff --git a/serialize.go b/serialize.go
index 6fdf68d0d4dd81d0e64119637838c85b109cf435..47f8f9fd366a7b74fc1089855b1514d9c406250c 100644 (file)
--- a/serialize.go
+++ b/serialize.go
@@ -156,7 +156,16 @@ func Serialize(blk *MapBlk, w io.Writer, idNameMap map[string]mt.Content) error
                return err
        }
 
+       var exists = make(map[mt.Content]struct{})
+       for i := 0; i < 4096; i++ {
+               exists[blk.Param0[i]] = struct{}{}
+       }
+
        for name, id := range idNameMap {
+               if _, ok := exists[id]; !ok {
+                       continue
+               }
+
                if err := binary.Write(w, binary.BigEndian, &id); err != nil {
                        return err
                }