Struct bevy::time::Virtual

pub struct Virtual { /* private fields */ }
Expand description

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§

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impl Clone for Virtual

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fn clone(&self) -> Virtual

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for Virtual

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

Formats the value using the given formatter. Read more
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impl Default for Virtual

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fn default() -> Virtual

Returns the “default value” for a type. Read more
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impl FromReflect for Virtual

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fn from_reflect(reflect: &(dyn Reflect + 'static)) -> Option<Virtual>

Constructs a concrete instance of Self from a reflected value.
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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. Read more
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impl GetTypeRegistration for Virtual

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impl Reflect for Virtual

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

Returns the TypeInfo of the type represented by this value. Read more
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fn into_any(self: Box<Virtual>) -> Box<dyn Any>

Returns the value as a Box<dyn Any>.
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fn as_any(&self) -> &(dyn Any + 'static)

Returns the value as a &dyn Any.
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fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

Returns the value as a &mut dyn Any.
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fn into_reflect(self: Box<Virtual>) -> Box<dyn Reflect>

Casts this type to a boxed reflected value.
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fn as_reflect(&self) -> &(dyn Reflect + 'static)

Casts this type to a reflected value.
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fn as_reflect_mut(&mut self) -> &mut (dyn Reflect + 'static)

Casts this type to a mutable reflected value.
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fn clone_value(&self) -> Box<dyn Reflect>

Clones the value as a Reflect trait object. Read more
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fn set(&mut self, value: Box<dyn Reflect>) -> Result<(), Box<dyn Reflect>>

Performs a type-checked assignment of a reflected value to this value. Read more
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fn apply(&mut self, value: &(dyn Reflect + 'static))

Applies a reflected value to this value. Read more
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fn reflect_kind(&self) -> ReflectKind

Returns a zero-sized enumeration of “kinds” of type. Read more
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fn reflect_ref(&self) -> ReflectRef<'_>

Returns an immutable enumeration of “kinds” of type. Read more
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fn reflect_mut(&mut self) -> ReflectMut<'_>

Returns a mutable enumeration of “kinds” of type. Read more
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fn reflect_owned(self: Box<Virtual>) -> ReflectOwned

Returns an owned enumeration of “kinds” of type. Read more
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fn reflect_partial_eq(&self, value: &(dyn Reflect + 'static)) -> Option<bool>

Returns a “partial equality” comparison result. Read more
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fn reflect_hash(&self) -> Option<u64>

Returns a hash of the value (which includes the type). Read more
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fn debug(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Debug formatter for the value. Read more
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fn serializable(&self) -> Option<Serializable<'_>>

Returns a serializable version of the value. Read more
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fn is_dynamic(&self) -> bool

Indicates whether or not this type is a dynamic type. Read more
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impl Struct for Virtual

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

Returns a reference to the value of the field named name as a &dyn Reflect.
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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.
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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.
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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.
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fn name_at(&self, index: usize) -> Option<&str>

Returns the name of the field with index index.
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fn field_len(&self) -> usize

Returns the number of fields in the struct.
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fn iter_fields(&self) -> FieldIter<'_>

Returns an iterator over the values of the reflectable fields for this struct.
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fn clone_dynamic(&self) -> DynamicStruct

Clones the struct into a DynamicStruct.
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impl TypePath for Virtual
where Virtual: Any + Send + Sync,

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fn type_path() -> &'static str

Returns the fully qualified path of the underlying type. Read more
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fn short_type_path() -> &'static str

Returns a short, pretty-print enabled path to the type. Read more
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fn type_ident() -> Option<&'static str>

Returns the name of the type, or None if it is anonymous. Read more
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fn crate_name() -> Option<&'static str>

Returns the name of the crate the type is in, or None if it is anonymous. Read more
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fn module_path() -> Option<&'static str>

Returns the path to the module the type is in, or None if it is anonymous. Read more
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impl Typed for Virtual

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fn type_info() -> &'static TypeInfo

Returns the compile-time info for the underlying type.
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impl Copy for Virtual

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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fn as_bind_group_shader_type(&self, _images: &RenderAssets<Image>) -> U

Return the T ShaderType for self. When used in AsBindGroup derives, it is safe to assume that all images in self exist.
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impl<T> Borrow<T> for T
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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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Mutably borrows from an owned value. Read more
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fn downcast(&self) -> &T

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impl<T> Downcast for T
where T: Any,

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

Convert Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can then be further downcast into Box<ConcreteType> where ConcreteType implements Trait.
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Convert &Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &Any’s vtable from &Trait’s.
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Convert &mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &mut Any’s vtable from &mut Trait’s.
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Convert Arc<Trait> (where Trait: Downcast) to Arc<Any>. Arc<Any> can then be further downcast into Arc<ConcreteType> where ConcreteType implements Trait.
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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> FromWorld for T
where T: Default,

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fn from_world(_world: &mut World) -> T

Creates Self using data from the given World.
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where T: Reflect,

Returns a reference to the value of the field named name, downcast to T.
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where T: Reflect,

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Calls U::from(self).

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The none-equivalent value.
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const ALIGN: usize = _

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unsafe fn init(init: <T as Pointable>::Init) -> usize

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