Smooth MultiPlayer movement

Question

i am developing a multiplayer roleplaying game, (No, its not a mmorpg. ;)

My current setup is like this.

Client tells the server "I want to move forward"/"I want to move backwards", the server then updates your entity, and informs all clients in the area about the change. The server is also updating each entity every 20ms and sending updates every 100ms to the clients, these updates contains position, velocity, rotation etc.

So far so good, however i have nothing in store for smoothing the movement between the packets on the client side, and i must say, i can not get it working. I have been reading up on prediction, interpolation, deadreackoning but its all a big mess for me.

So right now i am just doing something like "Position = Packet.Position", which causes a very stuttering movement.

So, what i want help with is, how do i get a more smooth movement? Have been looking at the XNA Prediction Sample, but i could not get it right.

Thanks //F

Answer 1

I'd suggest the idea from another question (see the accepted answer)

Here the client calculates its position itself as if its not a network game. Client regularly sends his current position to the server. And if client cheats or can't continue moving in the chosen direction, server just sends the client his correct position.

The same algorithm was used in Ultima Online (at least when I was playing it 10 years ago)

Answer 2

Read Valve's description of their multiplayer protocol. It should be instructive, and gives a very clear example on how you do the prediction/interpolation.

Answer 3

I solved it by running a ghost entity alongside with my main one.
The ghost will get updated every frame aswell, but whenever a packet comes in, his values are set to the values of the packet.

I then gradually tweak the real entity to where the ghost is.