[−][src]Struct hierarchical_pathfinding::PathCache
A struct to store the Hierarchical Pathfinding information.
Methods
impl<N: Neighborhood> PathCache<N>
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pub fn new(
(width, height): (usize, usize),
get_cost: impl FnMut(Point) -> isize,
neighborhood: N,
config: PathCacheConfig
) -> PathCache<N>
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(width, height): (usize, usize),
get_cost: impl FnMut(Point) -> isize,
neighborhood: N,
config: PathCacheConfig
) -> PathCache<N>
Creates a new PathCache
Arguments
(width, height)
- the size of the Gridget_cost
- get the cost for walking over a Tile. (Cost < 0 => solid Tile)neighborhood
- the Neighborhood to use. (SeeNeighborhood
)config
- optional config for creating the cache. (SeePathCacheConfig
)
Examples
Basic usage:
use hierarchical_pathfinding::{prelude::*, Point}; // create and initialize Grid // 0 = empty, 1 = swamp, 2 = wall let mut grid = [ [0, 2, 0, 0, 0], [0, 2, 2, 2, 0], [0, 1, 0, 0, 0], [0, 1, 0, 2, 0], [0, 0, 0, 2, 0], ]; let (width, height) = (grid.len(), grid[0].len()); const COST_MAP: [isize; 3] = [1, 10, -1]; fn cost_fn<'a>(grid: &'a [[usize; 5]; 5]) -> impl 'a + FnMut(Point) -> isize { move |(x, y)| COST_MAP[grid[y][x]] } let mut pathfinding = PathCache::new( (width, height), // the size of the Grid cost_fn(&grid), // get the cost for walking over a Tile ManhattanNeighborhood::new(width, height), // the Neighborhood PathCacheConfig { chunk_size: 3, ..Default::default() }, // config );
pub fn find_path(
&mut self,
start: Point,
goal: Point,
get_cost: impl FnMut(Point) -> isize
) -> Option<AbstractPath<N>>
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&mut self,
start: Point,
goal: Point,
get_cost: impl FnMut(Point) -> isize
) -> Option<AbstractPath<N>>
Calculates the Path from start
to goal
on the Grid.
If no Path could be found, None
is returned.
This function takes a mutable reference of self, because start
and goal
need to be
inserted into the Abstract Graph in order for the algorithm to work. They are removed at
the end unless config.keep_insertions
was set to
true
(default) when creating the PathCache.
Arguments
start
the Point where the search startsgoal
the Point to search for. This may be a solid Tile.get_cost
get the cost for walking over a Tile. (Cost < 0 => solid Tile)
Examples
Basic usage:
let start = (0, 0); let goal = (4, 4); // find_path returns Some(Path) on success let path = pathfinding.find_path( start, goal, cost_fn(&grid), ); assert!(path.is_some()); let path = path.unwrap(); assert_eq!(path.cost(), 12);
The return Value gives the total Cost of the Path using cost()
and allows to iterate over
the Points in the Path.
Note: Setting config.cache_paths
to false
means
that the Paths need to be recalculated as needed. This means that for any sections of the
Path that are not present, safe_next
needs to be called to supply the Cost function.
Calling next
in that scenario would lead to a Panic.
Using the Path:
let mut player = Player { pos: (0, 0), //... }; let goal = (4, 4); let mut path = pathfinding.find_path( player.pos, goal, cost_fn(&grid), ).unwrap(); player.move_to(path.next().unwrap()); assert_eq!(player.pos, (0, 1)); // wait for next turn or whatever player.move_to(path.next().unwrap()); assert_eq!(player.pos, (0, 2));
If the Grid changes, any Path objects still in use may become invalid. You can still use them if you are certain that nothing in relation to that Path changed, but it is discouraged and can lead to undefined behavior or panics.
Obtaining the entire Path:
// ... let path = path.unwrap(); let points: Vec<(usize, usize)> = path.collect(); assert_eq!( points, vec![(0, 1), (0, 2), (0, 3), (0, 4), (1, 4), (2, 4), (2, 3), (2, 2), (3, 2), (4, 2), (4, 3), (4, 4)], );
pub fn find_paths(
&mut self,
start: Point,
goals: &[Point],
get_cost: impl FnMut(Point) -> isize
) -> HashMap<Point, AbstractPath<N>>
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&mut self,
start: Point,
goals: &[Point],
get_cost: impl FnMut(Point) -> isize
) -> HashMap<Point, AbstractPath<N>>
Calculates the Paths from one start
to several goals
on the Grid.
This is equivalent to find_path
, except that it is optimized to handle multiple Goals
at once. However, it is slower for very few goals, since it does not use a heuristic like
find_path
does.
Instead of returning a single Option, it returns a Hashmap, where the position of the Goal is the key, and the Value is a Tuple of the Path and the Cost of that Path.
See find_path
for more details on how to use the returned Path.
Arguments
start
the Point where the search startsgoals
the Points to search for. They may be a solid Tiles.get_cost
get the cost for walking over a Tile. (Cost < 0 => solid Tile)
Examples
Basic usage:
let start = (0, 0); let goals = [(4, 4), (2, 0)]; // find_paths returns a HashMap<goal, Path> for all successes let paths = pathfinding.find_paths( start, &goals, cost_fn(&grid), ); // (4, 4) is reachable assert!(paths.contains_key(&goals[0])); // (2, 0) is not reachable assert!(!paths.contains_key(&goals[1]));
The returned Path is always equivalent to the one returned by find_path
:
let start = (0, 0); let goal = (4, 4); let paths = pathfinding.find_paths( start, &[goal], cost_fn(&grid), ); let dijkstra_path: Vec<Point> = paths[&goal].clone().collect(); let a_star_path: Vec<Point> = pathfinding.find_path( start, goal, cost_fn(&grid), ).unwrap().collect(); assert_eq!(dijkstra_path, a_star_path);
pub fn tiles_changed(
&mut self,
tiles: &[Point],
get_cost: impl FnMut(Point) -> isize
)
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&mut self,
tiles: &[Point],
get_cost: impl FnMut(Point) -> isize
)
Notifies the PathCache that the Grid changed.
This Method updates any internal Paths that might have changed when the Grid changed. This
is an expensive operation and should only be performed if the change affected the walking
cost of a tile and the PathCache is needed again. If possible, try to bundle as many
changes as possible into a single call to tiles_changed
to avoid unnecessary
recalculations.
Side note: if anybody has a way to improve this method, open a GitHub Issue / Pull Request.
Examples
Basic usage:
let (start, goal) = ((0, 0), (2, 0)); let path = pathfinding.find_path(start, goal, cost_fn(&grid)); assert!(path.is_none()); grid[1][2] = 0; grid[3][2] = 2; assert_eq!(grid, [ [0, 2, 0, 0, 0], [0, 2, 0, 2, 2], [0, 1, 0, 0, 0], [0, 1, 2, 2, 0], [0, 0, 0, 2, 0], ]); pathfinding.tiles_changed( &[(2, 1), (2, 3)], cost_fn(&grid), ); let path = pathfinding.find_path(start, goal, cost_fn(&grid)); assert!(path.is_some());
pub fn inspect_nodes(&self) -> CacheInspector<N>
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Allows for debugging and visualizing the PathCache
The returned object gives read-only access to the current state of the PathCache, mainly the Nodes and how they are connected to each other
Examples
Basic usage:
// create PathCache // only draw the connections between Nodes once let mut visited = HashSet::new(); for node in pathfinding.inspect_nodes() { let pos = node.pos(); // draw Node at x: pos.0, y: pos.1 visited.insert(node.id()); for neighbor in node.connected().filter(|n| !visited.contains(&n.id())) { let other_pos = neighbor.pos(); // draw Line from pos to other_pos } }
pub fn config(&self) -> PathCacheConfig
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Returns the config used to create this PathCache
Trait Implementations
impl<N: Clone + Neighborhood> Clone for PathCache<N>
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fn clone(&self) -> PathCache<N>
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fn clone_from(&mut self, source: &Self)
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Performs copy-assignment from source
. Read more
impl<N: Debug + Neighborhood> Debug for PathCache<N>
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Auto Trait Implementations
impl<N> Unpin for PathCache<N> where
N: Unpin,
N: Unpin,
impl<N> !Sync for PathCache<N>
impl<N> !Send for PathCache<N>
impl<N> !RefUnwindSafe for PathCache<N>
impl<N> UnwindSafe for PathCache<N> where
N: UnwindSafe,
N: UnwindSafe,
Blanket Implementations
impl<T> From<T> for T
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impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
fn to_owned(&self) -> T
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fn clone_into(&self, target: &mut T)
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,