writeBinary Causes unused textures to be lost

[wxxewx]

io.writeBinary(doc) Causes my unused textures to be lost。These textures are referenced in the extension，Use is VRM

[donmccurdy]

io.writeBinary(doc) won't remove unused textures — Unless you're also using the prune() function, unused resources are kept. However, it is possible that the order and indices of textures might change, and if a custom extension references those textures, but isn't implemented and registered as a custom extension, then its texture reference index might be wrong.

Without more information I won't be able to investigate further, so please share code models to debug if you believe there is a bug. Thanks!