• 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
xiongyouyi

time-slicing or multithreading for pathfinding?

9 posts in this topic

What are your requirements?

In many situations you should need neither for the following reasons :-)[list]
[*]Time-slicing implies your pathfinding requests take longer than a frame. Best optimize them or use an algorithm that fits comfortably within a frame. Then do an integer number of them each frame.
[*]Multi-threaded pathfinding is used on PS3, but often on XBox360 or PC there's a separate (single) thread for pathfinding.
[/list]
Keep in mind that either of these choices can result in your AI being much less deterministic if you're not very careful!

Alex
1

Share this post


Link to post
Share on other sites
[quote name='alexjc' timestamp='1341210944' post='4954800']
What are your requirements?

In many situations you should need neither for the following reasons :-)[list]
[*]Time-slicing implies your pathfinding requests take longer than a frame. Best optimize them or use an algorithm that fits comfortably within a frame. Then do an integer number of them each frame.
[*]Multi-threaded pathfinding is used on PS3, but often on XBox360 or PC there's a separate (single) thread for pathfinding.
[/list]
Keep in mind that either of these choices can result in your AI being much less deterministic if you're not very careful!

Alex
[/quote]

Thanks Alex! I'm planning to make a RTS game, use NavMesh and RVO for AI navigation, so if there are hundreds of units request pathfinding at same time, I don't know which solution is the best.
0

Share this post


Link to post
Share on other sites
If you have to service large volumes of path requests, just do them in batches - 20 in one frame, 20 in the next frame, and so on. (20 is just a made-up number, of course.)

You shouldn't really ever run into a situation where you absolutely [i]have[/i] to have hundreds of path results in the same frame.
1

Share this post


Link to post
Share on other sites
[quote name='ApochPiQ' timestamp='1341212935' post='4954810']
If you have to service large volumes of path requests, just do them in batches - 20 in one frame, 20 in the next frame, and so on. (20 is just a made-up number, of course.)

You shouldn't really ever run into a situation where you absolutely [i]have[/i] to have hundreds of path results in the same frame.
[/quote]
I want to test multithreaded path finding for large units.
0

Share this post


Link to post
Share on other sites
What do you mean by "multithreaded pathfinding" though? Running multiple path queries on separate threads concurrently, or using multiple threads for a single query?
0

Share this post


Link to post
Share on other sites
[quote name='ApochPiQ' timestamp='1341250971' post='4954970']
What do you mean by "multithreaded pathfinding" though? Running multiple path queries on separate threads concurrently, or using multiple threads for a single query?
[/quote]

I mean running multiple path queries on separate threads concurrently, it will not affect the fps.
0

Share this post


Link to post
Share on other sites
Assuming you use a fairly standard approach of high-level pathfinding combined with local steering for avoiding other units, you should be able to just run a copy of the path search on as many threads as you like (assuming your searches don't mutate any state of course).
0

Share this post


Link to post
Share on other sites
I use a combination of both, multiple threads calculates multiple pathes concurrently in a timesliced manner. The reason is, that my waypoint graph will be manipulated dynamically, by either setting waypoint attributes (open/closed doors etc.) or by changing the topology of the whole graph.
0

Share this post


Link to post
Share on other sites
If you have multiple pathsfindings to do, run that process on a thread with affinity set (especially if most of the map can fit in its cache) let each one finish before starting the next (especially if the map is dynamic -- units positions count as 'terrain' block movement factor) so that that result can be passed on to another process to get something done..

Multiple core - definitely have as a seperate thread (and if you profile and find that it gets done and has time left on that core you might have someother lightweight task for it to do to fill out its capacity.


If you have too much pathfinding to do then you need a priority scheme to figure out the best ones to calculate first (and do less importants ones less often - but still get done within some maximum timespan)
Eaxmple would be units who's target has moved over one that hasnt....

See if you can do a hierarchical scheme to simplify the processing (depends on terrain but interiors with obvious 'portals and coarse paths limited by the terrain are good candidates for this)

Also recycling the old path (if you have memory to keep it) can shortcut processing on subsequent pathfindings.

Optimizing the pathfinder itself can often speed up the processing by a magnitude (make use of the specifics of your map data, instead of a generalized A* )
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