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I want to talk about some problems with pathfinding for large armies and proposed solutions. I would implement these solutions and submit a patch. If you have a big group of units gathered together with no formation, and select them and click for them to move somewhere across the map (or even relatively nearby), two things happen. The units in front start moving immediately, but it takes a long time before the entire group is moving. The group narrows into a single-file column as each unit tries to follow exactly along the planned long-range path. Neither of these things is what the player wants. The army would get to the destination faster if every unit started moving immediately, and it would be more effective once the fighting starts if it stayed together as a clump. The more spread out the army is, the more vulnerable it is. I want to pause here and say that I don't intend to do anything with formations. These changes can be accomplished through individual unit pathfinding alone. I want to compare this to other RTS games such as Starcraft II. In Starcraft II, if you have a clump of units and tell them to move, the entire clump instantly start moving, and stays together as a clump. You can see examples of Starcraft II pathfinding here: https://www.youtube.com/watch?v=x0gSVKVZ4YU. Throughout the video, notice how units stay in tight groups, even as they move around and change direction a lot. If they split up, that's generally because the player manually split them up by telling part of the group to go one way and another part to go another way. Starcraft II has no formations. So how can 0ad work like this? I plan on the following changes. For reference, this is the current pathfinder doc: http://trac.wildfiregames.com/browser/ps/trunk/docs/pathfinder.pdf Add additional information to units giving their expected direction. This is a vector saying where and how fast the unit is probably going to move in the next turn. It doesn't have to be perfect. If you give a unit a walk order, its expected direction would be immediately set to be parallel to the long-range path to the destination. Otherwise, a unit's expected direction would be set to the direction it moved in the previous turn. This information would only be updated once per turn. For the purpose of short-range pathfinding, units ignore units whose expected direction would move away from them fast enough that there is no expected collision during the next turn. This should solve the issue where it takes a long time for a group to get moving because of units treating units in front of them as obstructions. As a side benefit, this would improve performance because the short-range pathfinder would have fewer edges to consider!! After short-range paths have been selected for units, units with short-range paths that are nearly parallel to allied units adjacent to them, should have their paths adjusted to be exactly parallel. This would prevent units from converging into a single-file column over long distances, by keeping a group moving in a parallel direction. A unit is considered to have passed a waypoint (but not a final destination) if the closest point on the long-range path is at or beyond the waypoint. This is necessary in combination with change 3, to keep units from insisting on stepping directly on every waypoint even when other allies who were going in the same direction are in the way. edit: After further examination, I see there's another major reason for why groups of units take a long time to fully start moving. Units ask for a new short term path as soon as they encounter an obstacle, even if the obstacle is moving. Asking for a short term path causes the unit to stop for a bit. You can see this by ordering a cluster of stationary units to move with the speed set to Turtle (0.1x). You can see units freeze in place for a second, waiting for a path, before starting to move in a direction perpendicular to where they were ordered. To fix this, units should keep trying to move for a short period of time if they were obstructed by a moving unit, and only ask for a new path if this doesn't work. This would be in addition to the other changes. As it would result in fewer calls to the pathfinder, this would also improve performance. staticsliding.diff

Better ask someone like leper or perhaps Philip first. They should have a better idea of what the xmb file are, and if those file can work without xml.