By tracking updates on the ActorMap the HierarchicalPathFinder can be aware of actors moving around the map. We track a subset of immovable actors that always block. These actors can be treated as impassable obstacles just like terrain. When a path needs to be found the abstract path will guide the search around this subset of immovable actors just like it can guide the search around impassable terrain. For path searches that were previously imperformant because some immovable actors created a bottleneck that needed to be routed around, these will now be performant instead. Path searches with bottlenecks created by items such as trees, walls and buildings should see a performance improvement. Bottlenecks created by other units will not benefit.
We now maintain two sets of HPFs. One is aware of immovable actors and will be used for path searches that request BlockedByActor.Immovable, BlockedByActor.Stationary and BlockedByActor.All to guide that around the immovable obstacles. The other is aware of terrain only and will be used for searches that request BlockedByActor.None, or if an ignoreActor is provided. A new UI dropdown when using the `/hpf` command will allow switching between the visuals of the two sets.
When this cheat is used by notifying of shroud changes we invoke the usual logic that would occur if the visibility had been granted by units. Without this change any cached information about the visibility is not refreshed. Without this refresh actors with different visibility may not act correctly.
One aspect this improves is frozen actors. Using the visibility cheat will show up all actors on the map. If the cheat is then disabled than frozen actors will appear in their place. Prior to this change a frozen actor would fail to appear if the cheat had caused it to be revealed. Healthbars and selection boxes are also made consistent for similar reasons.
Since bbf5970bc1 we update frozen actors only when required.
In 8339c6843e a regression was fixed where actors created in line of sight would be invisible.
Here, we fix a related regression where cloaked units that are revealed, and then frozen when you move out of line of sight would lack tooltips.
The fix centers around the setting of the Hidden flag. In the old code this used CanBeViewedByPlayer which checks for visibility modifiers and then uses the default visibility. The bug with this code is that when a visibility modifier was not hiding the actor, then we would report the default visibility state instead. However the frozen visibility state applies here which means if the frozen actor is visible, then we consider the actor to be hidden and therefore tooltips will not appear. In the fixed version we only consider the modifiers. This means a visibility modifier such as Cloak can hide the frozen actor tooltips. But otherwise we do not consider the frozen actor to be hidden. This prevents a frozen actor from hiding its own tooltips in some unintended circular logic. Hidden now becomes just a flag to indicate if the visibility modifiers are overriding things, as intended.
Replaces the existing bi-directional search between points used by the pathfinder with a guided hierarchical search. The old search was a standard A* search with a heuristic of advancing in straight line towards the target. This heuristic performs well if a mostly direct path to the target exists, it performs poorly it the path has to navigate around blockages in the terrain. The hierarchical path finder maintains a simplified, abstract graph. When a path search is performed it uses this abstract graph to inform the heuristic. Instead of moving blindly towards the target, it will instead steer around major obstacles, almost as if it had been provided a map which ensures it can move in roughly the right direction. This allows it to explore less of the area overall, improving performance.
When a path needs to steer around terrain on the map, the hierarchical path finder is able to greatly improve on the previous performance. When a path is able to proceed in a straight line, no performance benefit will be seen. If the path needs to steer around actors on the map instead of terrain (e.g. trees, buildings, units) then the same poor pathfinding performance as before will be observed.
Two different issues were causing a path search to not explore cells in order of the cheapest estimated route first. This meant the search could sometimes miss a cheaper route and return a suboptimal path.
- PriorityQueue had a bug which would cause it to not check some elements when restoring the heap property of its internal data structure. Failing to do this would invalidate the heap property, meaning it would not longer return the items in correct priority order. Additional tests ensure this is covered.
- When a path search encountered the same cell again with a lower cost, it would not update the priority queue with the new cost. This meant the cell was not explored early enough as it was in the queue with its original, higher cost. Exploring other paths might close off surrounding cells, preventing the cell with the lower cost from progressing. Instead we now add a duplicate with the lower cost to ensure it gets explored at the right time. We remove the duplicate with the higher cost in CanExpand by checking for already Closed cells.
