Struct DirectionalNavigationMap

pub struct DirectionalNavigationMap {
    pub neighbors: EntityHashMap<NavNeighbors>,
}

A resource that stores the traversable graph of focusable entities.

Each entity can have up to 8 neighbors, one for each CompassOctant.

To ensure that your graph is intuitive to navigate and generally works correctly, it should be:

• Connected: Every focusable entity should be reachable from every other focusable entity.
• Symmetric: If entity A is a neighbor of entity B, then entity B should be a neighbor of entity A, ideally in the reverse direction.
• Physical: The direction of navigation should match the layout of the entities when possible, although looping around the edges of the screen is also acceptable.
• Not self-connected: An entity should not be a neighbor of itself; use None instead.

For now, this graph must be built manually, and the developer is responsible for ensuring that it meets the above criteria.

Fields

neighbors: EntityHashMap<NavNeighbors>

A directed graph of focusable entities.

Pass in the current focus as a key, and get back a collection of up to 8 neighbors, each keyed by a CompassOctant.

Implementations

impl DirectionalNavigationMap

pub fn remove(&mut self, entity: Entity)

Adds a new entity to the navigation map, overwriting any existing neighbors for that entity.

Removes an entity from the navigation map, including all connections to and from it.

Note that this is an O(n) operation, where n is the number of entities in the map, as we must iterate over each entity to check for connections to the removed entity.

If you are removing multiple entities, consider using remove_multiple instead.

pub fn remove_multiple(&mut self, entities: EntityHashSet)

Removes a collection of entities from the navigation map.

While this is still an O(n) operation, where n is the number of entities in the map, it is more efficient than calling remove multiple times, as we can check for connections to all removed entities in a single pass.

An EntityHashSet must be provided as it is noticeably faster than the standard hasher or a Vec.

pub fn clear(&mut self)

Completely clears the navigation map, removing all entities and connections.

pub fn add_edge(&mut self, a: Entity, b: Entity, direction: CompassOctant)

Adds an edge between two entities in the navigation map. Any existing edge from A in the provided direction will be overwritten.

The reverse edge will not be added, so navigation will only be possible in one direction. If you want to add a symmetrical edge, use add_symmetrical_edge instead.

pub fn add_symmetrical_edge( &mut self, a: Entity, b: Entity, direction: CompassOctant, )

Adds a symmetrical edge between two entities in the navigation map. The A -> B path will use the provided direction, while B -> A will use the CompassOctant::opposite variant.

Any existing connections between the two entities will be overwritten.

pub fn add_edges(&mut self, entities: &[Entity], direction: CompassOctant)

Add symmetrical edges between each consecutive pair of entities in the provided slice.

Unlike add_looping_edges, this method does not loop back to the first entity.

pub fn add_looping_edges( &mut self, entities: &[Entity], direction: CompassOctant, )

Add symmetrical edges between each consecutive pair of entities in the provided slice, looping back to the first entity at the end.

This is useful for creating a circular navigation path between a set of entities, such as a menu.

pub fn get_neighbor( &self, focus: Entity, octant: CompassOctant, ) -> Option<Entity>

Gets the entity in a given direction from the current focus, if any.

pub fn get_neighbors(&self, entity: Entity) -> Option<&NavNeighbors>

Looks up the neighbors of a given entity.

If the entity is not in the map, None will be returned. Note that the set of neighbors is not guaranteed to be non-empty though!

Trait Implementations

impl Clone for DirectionalNavigationMap

fn clone(&self) -> DirectionalNavigationMap

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for DirectionalNavigationMap

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for DirectionalNavigationMap

fn default() -> DirectionalNavigationMap

Returns the “default value” for a type.

impl FromReflect for DirectionalNavigationMap

where DirectionalNavigationMap: Any + Send + Sync, EntityHashMap<NavNeighbors>: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn from_reflect(reflect: &dyn PartialReflect) -> Option<Self>

Constructs a concrete instance of Self from a reflected value.

fn take_from_reflect( reflect: Box<dyn PartialReflect>, ) -> Result<Self, Box<dyn PartialReflect>>

Attempts to downcast the given value to Self using, constructing the value using from_reflect if that fails.

impl GetTypeRegistration for DirectionalNavigationMap

where DirectionalNavigationMap: Any + Send + Sync, EntityHashMap<NavNeighbors>: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn get_type_registration() -> TypeRegistration

Returns the default TypeRegistration for this type.

fn register_type_dependencies(registry: &mut TypeRegistry)

Registers other types needed by this type.

impl PartialEq for DirectionalNavigationMap

fn eq(&self, other: &DirectionalNavigationMap) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl PartialReflect for DirectionalNavigationMap

where DirectionalNavigationMap: Any + Send + Sync, EntityHashMap<NavNeighbors>: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn get_represented_type_info(&self) -> Option<&'static TypeInfo>

Returns the TypeInfo of the type represented by this value.

fn try_apply(&mut self, value: &dyn PartialReflect) -> Result<(), ApplyError>

Tries to apply a reflected value to this value.

fn reflect_kind(&self) -> ReflectKind

Returns a zero-sized enumeration of “kinds” of type.

fn reflect_ref(&self) -> ReflectRef<'_>

Returns an immutable enumeration of “kinds” of type.

fn reflect_mut(&mut self) -> ReflectMut<'_>

Returns a mutable enumeration of “kinds” of type.

fn reflect_owned(self: Box<Self>) -> ReflectOwned

Returns an owned enumeration of “kinds” of type.

fn try_into_reflect( self: Box<Self>, ) -> Result<Box<dyn Reflect>, Box<dyn PartialReflect>>

Attempts to cast this type to a boxed, fully-reflected value.

fn try_as_reflect(&self) -> Option<&dyn Reflect>

Attempts to cast this type to a fully-reflected value.

fn try_as_reflect_mut(&mut self) -> Option<&mut dyn Reflect>

Attempts to cast this type to a mutable, fully-reflected value.

fn into_partial_reflect(self: Box<Self>) -> Box<dyn PartialReflect>

Casts this type to a boxed, reflected value.

fn as_partial_reflect(&self) -> &dyn PartialReflect

Casts this type to a reflected value.

fn as_partial_reflect_mut(&mut self) -> &mut dyn PartialReflect

Casts this type to a mutable, reflected value.

fn reflect_partial_eq(&self, value: &dyn PartialReflect) -> Option<bool>

Returns a “partial equality” comparison result.

fn debug(&self, f: &mut Formatter<'_>) -> Result

Debug formatter for the value.

fn reflect_clone(&self) -> Result<Box<dyn Reflect>, ReflectCloneError>

Attempts to clone Self using reflection.

fn apply(&mut self, value: &(dyn PartialReflect + 'static))

Applies a reflected value to this value.

fn clone_value(&self) -> Box<dyn PartialReflect>

👎Deprecated since 0.16.0: to clone reflected values, prefer using reflect_clone. To convert reflected values to dynamic ones, use to_dynamic.

Clones Self into its dynamic representation.

fn to_dynamic(&self) -> Box<dyn PartialReflect>

Converts this reflected value into its dynamic representation based on its kind.

fn reflect_hash(&self) -> Option<u64>

Returns a hash of the value (which includes the type).

fn is_dynamic(&self) -> bool

Indicates whether or not this type is a dynamic type.

impl Reflect for DirectionalNavigationMap

where DirectionalNavigationMap: Any + Send + Sync, EntityHashMap<NavNeighbors>: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn into_any(self: Box<Self>) -> Box<dyn Any>

Returns the value as a Box<dyn Any>.

fn as_any(&self) -> &dyn Any

Returns the value as a &dyn Any.

fn as_any_mut(&mut self) -> &mut dyn Any

Returns the value as a &mut dyn Any.

fn into_reflect(self: Box<Self>) -> Box<dyn Reflect>

Casts this type to a boxed, fully-reflected value.

fn as_reflect(&self) -> &dyn Reflect

Casts this type to a fully-reflected value.

fn as_reflect_mut(&mut self) -> &mut dyn Reflect

Casts this type to a mutable, fully-reflected value.

fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>>

Performs a type-checked assignment of a reflected value to this value.

impl Struct for DirectionalNavigationMap

where DirectionalNavigationMap: Any + Send + Sync, EntityHashMap<NavNeighbors>: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn field(&self, name: &str) -> Option<&dyn PartialReflect>

Returns a reference to the value of the field named name as a &dyn PartialReflect.

fn field_mut(&mut self, name: &str) -> Option<&mut dyn PartialReflect>

Returns a mutable reference to the value of the field named name as a &mut dyn PartialReflect.

fn field_at(&self, index: usize) -> Option<&dyn PartialReflect>

Returns a reference to the value of the field with index index as a &dyn PartialReflect.

fn field_at_mut(&mut self, index: usize) -> Option<&mut dyn PartialReflect>

Returns a mutable reference to the value of the field with index index as a &mut dyn PartialReflect.

fn name_at(&self, index: usize) -> Option<&str>

Returns the name of the field with index index.

fn field_len(&self) -> usize

Returns the number of fields in the struct.

fn iter_fields(&self) -> FieldIter<'_>

Returns an iterator over the values of the reflectable fields for this struct.

fn to_dynamic_struct(&self) -> DynamicStruct

fn clone_dynamic(&self) -> DynamicStruct

👎Deprecated since 0.16.0: use to_dynamic_struct instead

Clones the struct into a DynamicStruct.

fn get_represented_struct_info(&self) -> Option<&'static StructInfo>

Will return None if TypeInfo is not available.

impl TypePath for DirectionalNavigationMap

where DirectionalNavigationMap: Any + Send + Sync,

fn type_path() -> &'static str

Returns the fully qualified path of the underlying type.

fn short_type_path() -> &'static str

Returns a short, pretty-print enabled path to the type.

fn type_ident() -> Option<&'static str>

Returns the name of the type, or None if it is anonymous.

fn crate_name() -> Option<&'static str>

Returns the name of the crate the type is in, or None if it is anonymous.

fn module_path() -> Option<&'static str>

Returns the path to the module the type is in, or None if it is anonymous.

impl Typed for DirectionalNavigationMap

where DirectionalNavigationMap: Any + Send + Sync, EntityHashMap<NavNeighbors>: FromReflect + TypePath + MaybeTyped + RegisterForReflection,

fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.

impl Resource for DirectionalNavigationMap

where Self: Send + Sync + 'static,

impl StructuralPartialEq for DirectionalNavigationMap