Effect on snapshots while reindexing

Does someone know if doing a reindex on a clustered or non-clustered index cause the snapshot file to grow? In other words, is the data that makes up the snapshot copied from the source to the snapshot database? If a normal reindex is done on the underlying database, will it block users from acessing the snapshot? Any help would be appreciated.

All the pages changed by the reindexing would be pushed to the snapshot so its files would grow. It should not cause any blocking in the snapshot, though there can be a significant increase in the IO load.