Struct bevy::prelude::Time

pub struct Time { /* private fields */ }

Tracks elapsed time since the last update and since the App has started

Implementations

impl Time

pub fn update(&mut self)

Updates the internal time measurements.

Calling this method on the Time resource as part of your app will most likely result in inaccurate timekeeping, as the resource is ordinarily managed by the TimePlugin.

pub fn update_with_instant(&mut self, instant: Instant)

Update time with a specified Instant

This method is provided for use in tests. Calling this method on the Time resource as part of your app will most likely result in inaccurate timekeeping, as the resource is ordinarily managed by the TimePlugin.

Examples

struct Health {
    // Health value between 0.0 and 1.0
    health_value: f32,
}

fn health_system(time: Res<Time>, mut health: ResMut<Health>) {
    // Increase health value by 0.1 per second, independent of frame rate,
    // but not beyond 1.0
    health.health_value = (health.health_value + 0.1 * time.delta_seconds()).min(1.0);
}

// Mock time in tests
fn test_health_system() {
    let mut world = World::default();
    let mut time = Time::default();
    time.update();
    world.insert_resource(time);
    world.insert_resource(Health { health_value: 0.2 });

    let mut update_stage = SystemStage::single_threaded();
    update_stage.add_system(health_system);

    // Simulate that 30 ms have passed
    let mut time = world.resource_mut::<Time>();
    let last_update = time.last_update().unwrap();
    time.update_with_instant(last_update + Duration::from_millis(30));

    // Run system
    update_stage.run(&mut world);

    // Check that 0.003 has been added to the health value
    let expected_health_value = 0.2 + 0.1 * 0.03;
    let actual_health_value = world.resource::<Health>().health_value;
    assert_eq!(expected_health_value, actual_health_value);
}

pub fn delta(&self) -> Duration

The delta between the current tick and last tick as a Duration

pub fn delta_seconds(&self) -> f32

The delta between the current and last tick as f32 seconds

pub fn delta_seconds_f64(&self) -> f64

The delta between the current and last tick as f64 seconds

pub fn seconds_since_startup(&self) -> f64

The time from startup to the last update in seconds

pub fn startup(&self) -> Instant

The Instant the app was started

pub fn last_update(&self) -> Option<Instant>

The Instant when Time::update was last called, if it exists

pub fn time_since_startup(&self) -> Duration

The Duration from startup to the last update

Trait Implementations

impl Clone for Time

fn clone(&self) -> Time

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Time

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

Formats the value using the given formatter.

impl Default for Time

fn default() -> Time

Returns the “default value” for a type.

impl GetTypeRegistration for Time

fn get_type_registration() -> TypeRegistration

impl Reflect for Time

fn type_name(&self) -> &str

Returns the type name of the underlying type.

fn get_type_info(&self) -> &'static TypeInfo

Returns the TypeInfo of the underlying type.

fn into_any(self: Box<Time, Global>) -> Box<dyn Any + 'static, Global>

Returns the value as a Box<dyn Any>.

fn as_any(&self) -> &(dyn Any + 'static)

Returns the value as a &dyn Any.

fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Returns the value as a &mut dyn Any.

fn as_reflect(&self) -> &(dyn Reflect + 'static)

Casts this type to a reflected value

fn as_reflect_mut(&mut self) -> &mut (dyn Reflect + 'static)

Casts this type to a mutable reflected value

fn clone_value(&self) -> Box<dyn Reflect + 'static, Global>

Clones the value as a Reflect trait object.

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

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

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

Applies a reflected value to this value.

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

Returns an enumeration of “kinds” of type.

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

Returns a mutable enumeration of “kinds” of type.

fn reflect_partial_eq(&self, value: &(dyn Reflect + 'static)) -> Option<bool>

Returns a “partial equality” comparison result.

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

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

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

Debug formatter for the value.

fn serializable(&self) -> Option<Serializable<'_>>

Returns a serializable version of the value.

impl Struct for Time

fn field(&self, name: &str) -> Option<&(dyn Reflect + 'static)>

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

fn field_mut(&mut self, name: &str) -> Option<&mut (dyn Reflect + 'static)>

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

fn field_at(&self, index: usize) -> Option<&(dyn Reflect + 'static)>

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

fn field_at_mut(&mut self, index: usize) -> Option<&mut (dyn Reflect + 'static)>

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

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 struct’s fields.

fn clone_dynamic(&self) -> DynamicStruct

Clones the struct into a DynamicStruct.

impl Typed for Time

fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.