Struct flat_spatial::shapegrid::ShapeGrid

pub struct ShapeGrid<O: Copy, S: Shape, ST: Storage<ShapeGridCell> = SparseStorage<ShapeGridCell>> { /* fields omitted */ }

ShapeGrid is a generic shape-based spatial partitioning structure that uses a generic storage of cells which acts as a grid instead of a tree.

Fast queries

In theory, ShapeGrid should be faster than a quadtree/r-tree because it has no log costs (calculating the cells around a point is trivial).
However, it only works if the cell size is adapted to the problem, much like how a tree has to be balanced to be efficient.

Dynamicity

ShapeGrid's allows eager removals and position updates, however for big shapes (spanning many cells) this can be expensive, so beware.

Use this grid for mostly static objects with the occasional removal/position update if needed.

A SlotMap is used for objects managing, adding a level of indirection between shapes and objects. SlotMap is used because removal doesn't alter handles given to the user, while still having constant time access. However it requires O to be copy, but SlotMap's author stated that they were working on a similar map where Copy isn't required.

About object managment

In theory, you don't have to use the object managment directly, you can make your custom Handle -> Object map by specifying "()" to be the object type. (This can be useful if your object is not Copy) Since () is zero sized, it should probably optimize away a lot of the object managment code.

use flat_spatial::ShapeGrid;
use flat_spatial::shape::Circle;

let mut g: ShapeGrid<(), Circle> = ShapeGrid::new(10);
let handle = g.insert(Circle {
    center: [0.0, 0.0].into(),
    radius: 3.0,
}, ());
// Use handle however you want

Examples

Here is a basic example that shows most of its capabilities:

use flat_spatial::ShapeGrid;
use flat_spatial::shape::Circle;

let mut g: ShapeGrid<i32, Circle> = ShapeGrid::new(10); // Creates a new grid with a cell width of 10 with an integer as extra data
let a = g.insert(Circle {
     center: [2.0, 2.0].into(),
     radius: 3.0,
}, 0); // Inserts a new circle with data: 0

{
    let mut before = g.query_around([0.0, 0.0], 5.0).map(|(id, _shape, _obj)| id); // Queries for circles intersecting around a given point
    assert_eq!(before.next(), Some(a));
    assert_eq!(g.get(a).unwrap().1, &0);
}
let b = g.insert(Circle {
     center: [1.0, 1.0].into(),
     radius: 3.0,
}, 1); // Inserts a new element, assigning a new unique and stable handle, with data: 1

g.remove(a); // Removes a value using the handle given by `insert`

assert_eq!(g.handles().collect::<Vec<_>>(), vec![b]); // We check that the "a" object has been removed

let after: Vec<_> = g.query_around([0.0, 0.0], 5.0).map(|(id, _shape, _obj)| id).collect(); // And that b is query-able
assert_eq!(after, vec![b]);

assert_eq!(g.get(b).unwrap().1, &1); // We also check that b still has his data associated
assert!(g.get(a).is_none()); // But that a doesn't exist anymore

Implementations

impl<S: Shape, ST: Storage<ShapeGridCell>, O: Copy> ShapeGrid<O, S, ST>

pub fn new(cell_size: i32) -> Self

Creates an empty grid.
The cell size should be about the same magnitude as your queries size.

pub fn with_storage(st: ST) -> Self

Creates an empty grid.
The cell size should be about the same magnitude as your queries size.

pub fn insert(&mut self, shape: S, obj: O) -> ShapeGridHandle

Inserts a new object with a position and an associated object Returns the unique and stable handle to be used with get_obj

Example

use flat_spatial::{ShapeGrid, shape::Circle};
let mut g: ShapeGrid<(), Circle> = ShapeGrid::new(10);
let h = g.insert(Circle {
     center: [2.0, 2.0].into(),
     radius: 3.0,
}, ());

pub fn set_shape(&mut self, handle: ShapeGridHandle, shape: S)

Updates the shape of an object.

Example

use flat_spatial::{ShapeGrid, shape::Circle};
let mut g: ShapeGrid<(), Circle> = ShapeGrid::new(10);
let h = g.insert(Circle {
     center: [2.0, 2.0].into(),
     radius: 3.0,
}, ());

g.set_shape(h, Circle {
     center: [61.0, 35.0].into(),
     radius: 8.0,
});

pub fn remove(&mut self, handle: ShapeGridHandle) -> Option<O>

Removes an object from the grid.

Example

use flat_spatial::{ShapeGrid, shape::Circle};
let mut g: ShapeGrid<(), Circle> = ShapeGrid::new(10);
let h = g.insert(Circle {
     center: [2.0, 2.0].into(),
     radius: 3.0,
}, ());
g.remove(h);

pub fn handles(&self) -> impl Iterator<Item = ShapeGridHandle> + '_

Iterate over all handles

pub fn objects(&self) -> impl Iterator<Item = &O> + '_

Iterate over all objects

pub fn get(&self, id: ShapeGridHandle) -> Option<(&S, &O)>

Returns a reference to the associated object and its position, using the handle.

Example

use flat_spatial::{ShapeGrid, shape::Circle};
let mut g: ShapeGrid<i32, [f32; 2]> = ShapeGrid::new(10);
let h = g.insert([5.0, 3.0], 42);
assert_eq!(g.get(h), Some((&[5.0, 3.0], &42)));

pub fn get_mut(&mut self, id: ShapeGridHandle) -> Option<(&S, &mut O)>

Returns a mutable reference to the associated object and its position, using the handle.

Example

use flat_spatial::{ShapeGrid, shape::Circle};
let mut g: ShapeGrid<i32, [f32; 2]> = ShapeGrid::new(10);
let h = g.insert([5.0, 3.0], 42);
*g.get_mut(h).unwrap().1 = 56;
assert_eq!(g.get(h).unwrap().1, &56);

pub fn storage(&self) -> &ST

The underlying storage

pub fn query<QS: Shape + Intersect<S> + 'static>(
    &self,
    shape: QS
) -> impl Iterator<Item = (ShapeGridHandle, &S, &O)> + '_

Queries for objects intersecting a given shape.

Example

use flat_spatial::{ShapeGrid, shape::Circle};

let mut g: ShapeGrid<(), Circle> = ShapeGrid::new(10);
let a = g.insert(Circle {
     center: [2.0, 2.0].into(),
     radius: 3.0,
}, ());
let b = g.insert(Circle {
     center: [5.0, 2.0].into(),
     radius: 3.0,
}, ());

let around: Vec<_> = g.query(Circle {
     center: [0.0, 0.0].into(),
     radius: 10.0,
}).map(|(id, _shape, _obj)| id).collect();

assert_eq!(vec![a, b], around);

pub fn query_broad<QS: Shape + 'static>(
    &self,
    shape: QS
) -> impl Iterator<Item = ShapeGridHandle> + '_

Queries for all objects in the cells intersecting the given shape

Exampley

use flat_spatial::{ShapeGrid, shape::Circle};

let mut g: ShapeGrid<(), Circle> = ShapeGrid::new(10);
let a = g.insert(Circle {
     center: [5.0, 5.0].into(),
     radius: 1.0,
}, ());

let around: Vec<_> = g.query_broad(Circle {
     center: [0.0, 0.0].into(),
     radius: 1.0,
}).collect();

assert_eq!(vec![a], around); // a is given even if it doesn't intersect, because this only looks at the cells

pub fn len(&self) -> usize

Returns the number of objects currently available (removals that were not confirmed with maintain() are still counted)

pub fn is_empty(&self) -> bool

Checks if the grid contains objects or not (removals that were not confirmed with maintain() are still counted)

impl<S: Shape, ST: Storage<ShapeGridCell>, O: Copy> ShapeGrid<O, S, ST> where
    Circle: Intersect<S>, 

pub fn query_around(
    &self,
    pos: impl Into<Point2<f32>>,
    radius: f32
) -> impl Iterator<Item = (ShapeGridHandle, &S, &O)> + '_

Queries for objects around a point, same as querying a circle at pos with a given radius.

Trait Implementations

impl<O: Clone + Copy, S: Clone + Shape, ST: Clone + Storage<ShapeGridCell>> Clone for ShapeGrid<O, S, ST>

fn clone(&self) -> ShapeGrid<O, S, ST>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.