Struct bevy_time::Virtual

pub struct Virtual { /* private fields */ }

The virtual game clock representing game time.

A specialization of the Time structure. For method documentation, see Time<Virtual>.

Normally used as Time<Virtual>. It is automatically inserted as a resource by TimePlugin and updated based on Time<Real>. The virtual clock is automatically set as the default generic Time resource for the update.

The virtual clock differs from real time clock in that it can be paused, sped up and slowed down. It also limits how much it can advance in a single update in order to prevent unexpected behavior in cases where updates do not happen at regular intervals (e.g. coming back after the program was suspended a long time).

The virtual clock can be paused by calling pause() and unpaused by calling unpause(). When the game clock is paused delta() will be zero on each update, and elapsed() will not grow. effective_speed() will return 0.0. Calling pause() will not affect value the delta() value for the update currently being processed.

The speed of the virtual clock can be changed by calling set_relative_speed(). A value of 2.0 means that virtual clock should advance twice as fast as real time, meaning that delta() values will be double of what Time<Real>::delta() reports and elapsed() will go twice as fast as Time<Real>::elapsed(). Calling set_relative_speed() will not affect the delta() value for the update currently being processed.

The maximum amount of delta time that can be added by a single update can be set by set_max_delta(). This value serves a dual purpose in the virtual clock.

If the game temporarily freezes due to any reason, such as disk access, a blocking system call, or operating system level suspend, reporting the full elapsed delta time is likely to cause bugs in game logic. Usually if a laptop is suspended for an hour, it doesn’t make sense to try to simulate the game logic for the elapsed hour when resuming. Instead it is better to lose the extra time and pretend a shorter duration of time passed. Setting max_delta() to a relatively short time means that the impact on game logic will be minimal.

If the game lags for some reason, meaning that it will take a longer time to compute a frame than the real time that passes during the computation, then we would fall behind in processing virtual time. If this situation persists, and computing a frame takes longer depending on how much virtual time has passed, the game would enter a “death spiral” where computing each frame takes longer and longer and the game will appear to freeze. By limiting the maximum time that can be added at once, we also limit the amount of virtual time the game needs to compute for each frame. This means that the game will run slow, and it will run slower than real time, but it will not freeze and it will recover as soon as computation becomes fast again.

You should set max_delta() to a value that is approximately the minimum FPS your game should have even if heavily lagged for a moment. The actual FPS when lagged will be somewhat lower than this, depending on how much more time it takes to compute a frame compared to real time. You should also consider how stable your FPS is, as the limit will also dictate how big of an FPS drop you can accept without losing time and falling behind real time.

Trait Implementations

impl Clone for Virtual

fn clone(&self) -> Virtual

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for Virtual

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

Formats the value using the given formatter.

impl Default for Virtual

fn default() -> Self

Returns the “default value” for a type.

impl FromReflect for Virtual

where Self: Any + Send + Sync, Duration: FromReflect + TypePath, bool: FromReflect + TypePath, f64: FromReflect + TypePath,

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

Constructs a concrete instance of Self from a reflected value.

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

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

impl GetTypeRegistration for Virtual

where Self: Any + Send + Sync, Duration: FromReflect + TypePath, bool: FromReflect + TypePath, f64: FromReflect + TypePath,

fn get_type_registration() -> TypeRegistration

impl Reflect for Virtual

where Self: Any + Send + Sync, Duration: FromReflect + TypePath, bool: FromReflect + TypePath, f64: FromReflect + TypePath,

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

Returns the TypeInfo of the type represented by this value.

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 reflected value.

fn as_reflect(&self) -> &dyn Reflect

Casts this type to a reflected value.

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

Casts this type to a mutable reflected value.

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

Clones the value as a Reflect trait object.

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

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

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

Applies 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 reflect_partial_eq(&self, value: &dyn Reflect) -> 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.

fn is_dynamic(&self) -> bool

Indicates whether or not this type is a dynamic type.

impl Struct for Virtual

where Self: Any + Send + Sync, Duration: FromReflect + TypePath, bool: FromReflect + TypePath, f64: FromReflect + TypePath,

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

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>

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>

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>

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 reflectable fields for this struct.

fn clone_dynamic(&self) -> DynamicStruct

Clones the struct into a DynamicStruct.

impl TypePath for Virtual

where Self: 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 Virtual

where Self: Any + Send + Sync, Duration: FromReflect + TypePath, bool: FromReflect + TypePath, f64: FromReflect + TypePath,

fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.

impl Copy for Virtual