Extrapolation, i have yet to cover this in maths :D

Hello Blender artists!
This particular question refers to any single person who has done a level maths i beleive!
I am looking to add extrapolation to my game networking, but i cannot find any information on the whole system. Essentially, the client will receive positions of the other client at a specified interval.

With that, you can work out the vector of movement and the velocity along that vector.
What i am unsure of is how to continue.
Here is some of my sample code.

import bge
from mathutils import *
own = cont.owner

before_last = [Vector([0,0,0]),timeA]
last_position = [Vector([0,2,0]),timeB]

velocity = path.magnitude/(timeB-timeA)

direction = path.normalized()
direction.magnitude = velocity
newposition = last_position[0]+direction/60
How can i use this over multiple logic ticks, when i am not receiving data?

If You set both position and calculated speed then bullet would do the rest of the jobb.

If the object don’t have physics It is trivial to calculate Yourself. Each tic:

newPos = oldPos + direction / 60 # if You use 60 logic tic per second.

odlPos and newPos should be Vectors.

Assuming distance_using_velocity should be just velosity in Your exampel and timeA and timeB is in seconds. … Hmm… more bugs in the code… The vectors should be subtracted - not summed, and You should take the magnitude of path when calculating velocity…

Oops, typo! yes they should be subtracted

To really sync things up over a network the problem is a bit bigger thou… The real problem is to translate a logic tic into a virtual ‘real’ time (to get the timeA and timeB right). Using real real time is not good enough unless fps is 100% steady at max. It can go like this:

Logic tic 1
Frame 1
Logic tic 2
Logic tic 3
Frame 2
Logic tic 4
Logic tic 5
Logic tic 6
Frame 3

All logic tics is virtually still 1/60 seconds, but logic tic 2 and 3 resp 4, 5 and 6 may in real time be immediate after each other while the real time between 1 and 2 resp 3 and 4 may be much longer.

We cant sync the logic tics over the network so network have to sync by real time.

I wonder if there is a api for getting the virtual time of the current logic tic - I’m quite sure BGE keep track of it internally.

Else it an interesting python problem - but it will not be as efficient or precise as getting at the internal tracking.

I’m not sure why not. I would use time.ctime(), and get the delay by halving the time it takes to send a packet to the server and receive a reply packet