• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Angus Hollands

Prediction correction

4 posts in this topic

Hey all, a typical question here today.
I have been using a form of prediction correction for a while, but I hadn't noticed that it failed with certain latency.
Whilst it may have been something i did in a later commit, I'm still not happy with it

Some notes:[list=1]
[*]I am unable to perform rollbacks / rewind physics
[*]I am therefore forward predicting the receipt of the input packet on the client
[/list]

At the moment, I am checking what the server state is in comparison to the prediction for that receival tick
Then I get the error vector, add it to the current position, and add it to all later received states. However, if an object is falling when it shouldn't be this creates some problems.
How would someone do this?
0

Share this post


Link to post
Share on other sites
Typically, rather than "add the error vector," what you should do is predict where the server object would be X time from now, and make the local object velocity be such that it will reach that predicted position at the time when the next packet should arrive (or some other fixed time into the future.)

For example, if you are currently display the object at (8, 12) and you get a packet saying the object is at (7,5) moving with velocity (-20, 10) and you use a 0.1 second extrapolation window, you would calculate the position in the future as (7,5)+(-20,10)*0.1, or (5,6). Because you are displaying the object at (8,12) you will set the velocity of the local object to ((5-8),(6-12))/0.1, or (-30,-60) in this case.

Look at the <a href='http://www.mindcontrol.org/~hplus/epic/'>Entity Position Interpolation Code</a> for a working example.
0

Share this post


Link to post
Share on other sites
Indeed, I am using EPIC for extrapolating remote entities already! However, how would you recommend correcting the client local agent?
0

Share this post


Link to post
Share on other sites
My reasoning against using inputs was because now that I use displacement and not velocity (independent from the Physics simulation) I could actually work out where the client would be from the inputs, except it wouldn't account for gravity, nor collision, so long time steps would mess it up. It seems an impossible solution, unless I were to write my own engine.
0

Share this post


Link to post
Share on other sites
If you speculate the client ahead of the server, and cannot re-run client simulation on correction because your physics engine cannot be made to do that, then you're in a tough place. You could try snapshotting all entity positions, place the player where it should be, step the physics forward, and then put all entities back where they are supposed to be. This could work if you can step the physics engine faster than real time when needed.

Another option is to display the player extrapolated just like every other entity. This, unfortunately, will lead to some "skating" in steering, and won't get rid of the initial latency when starting a movement.
0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0