OnSerializeNetworkView and rigidbody2D

I'm new to Unity networking. As a learning exercise I started with the following tutorial that many have suggested.

http://www.paladinstudios.com/2013/07/10/how-to-create-an-online-multiplayer-game-with-unity/

The tutorial is written for 3D. I'm trying to adjust it for 2D.

Everything works well until the step where I replace the default synchronization of the transform with my own OnSerializeNetworkView function in PlayerMovementScript.cs. Comments on the blog indicate others are having a similar issue.

Here is the behavior that I am seeing. I have two instances of the game running, Instance A and Instance B. Instance A is standalone and set to run in background. Instance B is running in the Unity Editor. The two instances successfully connect. I see no error messages in Instance B's console (I have network debugging enabled). As I move the player in Instance A, the movement is not visually updated in Instance B until the player gets close to a wall. Once the player gets close to a wall in Instance A, in Instance B that player will instantly teleport to the correct position in Instance B's display. The reverse is also true; moving the Instance B player is not updating in Instance A's display until the Instance B player gets close to a wall.

Below is my network view update code. Is this not the proper way to network update players controlled by 2D physics?

Code (csharp):

1.  
2. void OnSerializeNetworkView(BitStream stream, NetworkMessageInfo info)
3. {
4.    Vector3 syncPosition = Vector3.zero;
5.  
6.    if (stream.isWriting)
7.    {
8.       syncPosition = rigidbody2D.position;
9.       if (syncPosition != lastWritePosition)
10.       {
11.          stream.Serialize(ref syncPosition);
12.          lastWritePosition = syncPosition;
13.       }
14.    }
15.    else
16.    {
17.      stream.Serialize(ref syncPosition);
18.      rigidbody2D.position = syncPosition;
19.    }
20. }
21.  

Any help is appreciated.

 

Adding the following after line18 above seems to fix my issue.

Code (csharp):

1.  
2.       rigidbody2D.WakeUp();
3.  

 

I didn't work with the 2D stuff too much yet. Is it normal you have to WakeUp manually? I guess it's not.
At the moment, I don't see why this matters

 

The WakeUp/Sleep concept is described as an optimization to remove objects at rest from the physics simulation. I guess the optimization assumes objects will not get updates directly to their rigidBody2D.position. It assumes position changes will happen due to applied forces?

(As an experiment I moved the update to rigidBody2D.position out of OnSerializeNetworkView, and into FixedUpdate. I thought that maybe Unity expected all physics updates to happen in FixedUpdate. But moving it to FixedUpdate did not help either.)

 

I didn't experiment with the 2D physics so maybe things are a bit tricky here.
Does FixedUpdate apply to 2D physics, too?
Is there a setting like in 3D to make the object "Kinematic"? That setting helps if the object's position is driven by non-physics code.

 

Although I could not find a definitive answer, the 2D examples that I ran across do their rigidBody2D updates in FixedUpdate.

rigidBody2D does have 'Is Kinematic'. Selecting it did not help (surprisingly).

Unsurprisingly, if I set the rigidBody2D 'Sleeping Mode' to 'Never Sleep', then I no longer have to WakeUp to see the remote players movement.

 

Thanks for letting us know.
It makes sense that a sleeping physics object has to wake first.