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In a multiplayer game with bots running, only the host client runs bot logic. This logic must not alter the world state, or the host will desync from the other clients which do not run the bot logic. The bot logic can interact with the pathfinder. This can eventually flow into HierarchicalPathFinder.BuildGrid which calls AbstractCellForLocalCells to determine the abstract cells within the grid. This method chooses an abstract cell closest to the middle, but there can be multiple cells tied for this. The input comes from a local path search, whose ordering depends on current cell costs. Previously, this ordering could would influence which of the equally close cells we would choose. In this case we'd choose the first in the ordering. On non-host clients which don't run the bot logic, they may not build the grid until a later tick. If the cell costs have changed the the local path search would still explore the same set of cells, but the ordering may be different. With the previous behaviour, they could choose a different abstract cell from the equally close cells. This results in a diverged state where their abstract graph differs subtly from the host abstract graph. Eventually, a unit will path search in a manner where this state divergence causes it to take a different path, which will be detected as a desync. To fix the issue, we ensure we pick the same abstract cell no matter the ordering of the list, by inserting an arbitrary tiebreaker rule. This means the differing ordering of the explored cells from the local path search is still possible, but the ordering no longer influences the abstract cell we choose as a result. This keeps the state of the abstract graph in sync across the clients, and thus prevents units from making different pathfinding decisions and desyncing.
OpenRA
A Libre/Free Real Time Strategy game engine supporting early Westwood classics.
- Website: https://www.openra.net
- Chat: #openra on Libera (web) or Discord
- Repository: https://github.com/OpenRA/OpenRA
Please read the FAQ in our Wiki and report problems at https://github.com/OpenRA/OpenRA/issues.
Join the Forum for discussion.
Play
Distributed mods include a reimagining of
- Command & Conquer: Red Alert
- Command & Conquer: Tiberian Dawn
- Dune 2000
EA has not endorsed and does not support this product.
Check our Playing the Game Guide to win multiplayer matches.
Contribute
- Please read INSTALL.md and Compiling on how to set up an OpenRA development environment.
- See Hacking for a (now very outdated) overview of the engine.
- Read and follow our Code of Conduct.
- To get your patches merged, please adhere to the Contributing guidelines.
Mapping
- We offer a Mapping Tutorial as you can change gameplay drastically with custom rules.
- For scripted mission have a look at the Lua API.
- If you want to share your maps with the community, upload them at the OpenRA Resource Center.
Modding
- Download a copy of the OpenRA Mod SDK to start your own mod.
- Check the Modding Guide to create your own classic RTS.
- There exists an auto-generated Trait documentation to get started with yaml files.
- Some hints on how to create new OpenRA compatible Pixelart.
- Upload total conversions at our Mod DB profile.
Support
- Sponsor a mirror server if you have some bandwidth to spare.
- You can immediately set up a Dedicated Game Server.
License
Copyright (c) OpenRA Developers and Contributors This file is part of OpenRA, which is free software. It is made available to you under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. For more information, see COPYING.
Sponsors
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