Struct SpatialHash 

pub struct SpatialHash<T> { /* private fields */ }

A uniform-grid spatial hash map keyed by (cell_x, cell_y).

T must be Clone because a single large item may be registered in multiple cells simultaneously.

Implementations

impl<T: Clone> SpatialHash<T>

pub fn new(cell_size: f32) -> Option<Self>

Create an empty spatial hash with the given cell size.

cell_size should be chosen to match the typical object size: too small wastes memory, too large reduces query selectivity. 64.0 px is a good default for UI graphs; use smaller values for dense physics simulations.

pub fn insert(&mut self, rect: Rect, item: T)

Insert item into every cell that rect overlaps.

The item is cloned once per overlapping cell. For items that span many cells this can be expensive — prefer large cell_size for large objects.

pub fn query(&self, rect: Rect) -> Vec<T>

Return all items registered in cells that overlap rect.

The returned list may contain duplicates if an item spans multiple cells that all overlap the query rect. Callers must deduplicate if needed. This is intentionally a broad-phase query — exact AABB testing is the caller’s responsibility.

pub fn clear(&mut self)

Remove all items from every cell, resetting to an empty grid.

This does NOT free the backing HashMap’s allocated memory; call this at the start of each frame before re-inserting the current object set.

pub fn len(&self) -> usize

Return the number of cell-item registrations (not unique item count).

This is useful for profiling and capacity planning. An item spanning N cells contributes N to this count.

pub fn is_empty(&self) -> bool

Returns true if no items have been inserted since the last clear().