Struct bevy::render::Extract

pub struct Extract<'w, 's, P>where
    P: 'static + SystemParam,
    <P as SystemParam>::Fetch: ReadOnlySystemParamFetch,{ /* private fields */ }

A helper for accessing MainWorld content using a system parameter.

A SystemParam adapter which applies the contained SystemParam to the World contained in MainWorld. This parameter only works for systems run during RenderStage::Extract.

This requires that the contained SystemParam does not mutate the world, as it uses a read-only reference to MainWorld internally.

Context

RenderStage::Extract is used to extract (move) data from the simulation world (MainWorld) to the render world. The render world drives rendering each frame (generally to a Window). This design is used to allow performing calculations related to rendering a prior frame at the same time as the next frame is simulated, which increases throughput (FPS).

Extract is used to get data from the main world during RenderStage::Extract.

Examples

use bevy_ecs::prelude::*;
use bevy_render::Extract;
fn extract_clouds(mut commands: Commands, clouds: Extract<Query<Entity, With<Cloud>>>) {
    for cloud in &clouds {
        commands.get_or_spawn(cloud).insert(Cloud);
    }
}

Trait Implementations

impl<'w, 's, P> Deref for Extract<'w, 's, P>where
    P: SystemParam,
    <P as SystemParam>::Fetch: ReadOnlySystemParamFetch,

type Target = <<P as SystemParam>::Fetch as SystemParamFetch<'w, 's>>::Item

The resulting type after dereferencing.

fn deref(&self) -> &<Extract<'w, 's, P> as Deref>::Target

Dereferences the value.

impl<'w, 's, P> DerefMut for Extract<'w, 's, P>where
    P: SystemParam,
    <P as SystemParam>::Fetch: ReadOnlySystemParamFetch,

fn deref_mut(&mut self) -> &mut <Extract<'w, 's, P> as Deref>::Target

Mutably dereferences the value.

impl<'a, 'w, 's, P> IntoIterator for &'a Extract<'w, 's, P>where
    P: SystemParam,
    <P as SystemParam>::Fetch: ReadOnlySystemParamFetch,
    &'a <<P as SystemParam>::Fetch as SystemParamFetch<'w, 's>>::Item: IntoIterator,

type Item = <&'a <<P as SystemParam>::Fetch as SystemParamFetch<'w, 's>>::Item as IntoIterator>::Item

The type of the elements being iterated over.

type IntoIter = <&'a <<P as SystemParam>::Fetch as SystemParamFetch<'w, 's>>::Item as IntoIterator>::IntoIter

Which kind of iterator are we turning this into?

fn into_iter(self) -> <&'a Extract<'w, 's, P> as IntoIterator>::IntoIter

Creates an iterator from a value.

impl<'w, 's, P> SystemParam for Extract<'w, 's, P>where
    P: SystemParam,
    <P as SystemParam>::Fetch: ReadOnlySystemParamFetch,

type Fetch = ExtractState<P>