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Unity Multiplayer OnSerialize and dirty state (confused by docs)

Discussion in 'Multiplayer' started by liortal, Jun 13, 2015.

  1. liortal

    liortal

    Joined:
    Oct 17, 2012
    Posts:
    3,532
    Hey,

    I am a little confused by the docs on this matter (taken from: http://docs.unity3d.com/Manual/UNetStateSync.html)
    This is followed by the following (a few lines below):
    This seems to be contradictive. Can someone please explain how the flow really goes ?
     
    liortal, Jun 13, 2015
    #1

  2. seanr

    seanr

    Unity Technologies

    Joined:
    Sep 22, 2014
    Posts:
    669
    Yes, we need better examples and docs for this.

    • each networkbehaviour has a dirty mask.
    • changing SyncVars or calling SetDirtyBit() write to this mask
    • NetworkIdentity objects are checked on the server as part of it's update loop
    • if any networkbehaviours on a NetworkIdentity are dirty, then an UpdateVars packet is created for that object
    • this packet is populated by calling OnSerialize on each NetworkBehaviour on the object
    • NetworkBehaviour that are NOT dirty write a zero byte to the packet for their dirty bits
    • if OnSerialize returns true, the dirty mask is reset for that NetworkBehaviour
    • the packet is sent to ready clients that are observing the object

    • on the client, an UpdateVars packet is received for an object
    • OnDeserialize is called for each NetworkBehaviour script on the object
    • scripts read a dirty mask - if it is zero they return immediately
    • non-dirty scripts read data from the stream based on the dirty bits

    This is a little more complex in practice because different scripts can use different QoS channels. In that case, there is a packet for each channel.
     
    seanr, Jun 13, 2015
    #2

  3. liortal

    liortal

    Joined:
    Oct 17, 2012
    Posts:
    3,532
    This is still a bit confusing - you're saying that "if any networkbehaviours on a NetworkIdentity are dirty, then an UpdateVars packet is created for that object", but then "NetworkBehaviour that are NOT dirty write a zero byte to the packet for their dirty bits".

    How is that possible?

    The only scenario i can think is that if an object has multiple NetworkBehaviour scripts, where one might be marked as dirty (e.g: i updated a SyncVar on that script) and did not update the other scripts. This will trigger an update packet, where only the NetworkBehaviour whose SyncVar i updated will need to serialize its data, and all the others won't do anything (write a zero byte as you said).
     
    liortal, Jun 13, 2015
    #3

  4. seanr

    seanr

    Unity Technologies

    Joined:
    Sep 22, 2014
    Posts:
    669
    that is exactly correct.
     
    seanr, Jun 14, 2015
    #4